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ac2081cdc4
Although the arm64 single-step state machine can be fast-forwarded in cases where we wish to generate a SIGTRAP without actually executing an instruction, this has two major limitations outside of simply skipping an instruction due to emulation. 1. Stepping out of a ptrace signal stop into a signal handler where SIGTRAP is blocked. Fast-forwarding the stepping state machine in this case will result in a forced SIGTRAP, with the handler reset to SIG_DFL. 2. The hardware implicitly fast-forwards the state machine when executing an SVC instruction for issuing a system call. This can interact badly with subsequent ptrace stops signalled during the execution of the system call (e.g. SYSCALL_EXIT or seccomp traps), as they may corrupt the stepping state by updating the PSTATE for the tracee. Resolve both of these issues by injecting a pseudo-singlestep exception on entry to a signal handler and also on return to userspace following a system call. Cc: <stable@vger.kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Tested-by: Luis Machado <luis.machado@linaro.org> Reported-by: Keno Fischer <keno@juliacomputing.com> Signed-off-by: Will Deacon <will@kernel.org>
977 lines
24 KiB
C
977 lines
24 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Based on arch/arm/kernel/signal.c
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*
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* Copyright (C) 1995-2009 Russell King
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* Copyright (C) 2012 ARM Ltd.
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*/
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#include <linux/cache.h>
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#include <linux/compat.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/signal.h>
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#include <linux/personality.h>
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#include <linux/freezer.h>
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#include <linux/stddef.h>
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#include <linux/uaccess.h>
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#include <linux/sizes.h>
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#include <linux/string.h>
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#include <linux/tracehook.h>
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#include <linux/ratelimit.h>
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#include <linux/syscalls.h>
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#include <asm/daifflags.h>
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#include <asm/debug-monitors.h>
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#include <asm/elf.h>
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#include <asm/cacheflush.h>
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#include <asm/ucontext.h>
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#include <asm/unistd.h>
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#include <asm/fpsimd.h>
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#include <asm/ptrace.h>
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#include <asm/signal32.h>
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#include <asm/traps.h>
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#include <asm/vdso.h>
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/*
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* Do a signal return; undo the signal stack. These are aligned to 128-bit.
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*/
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struct rt_sigframe {
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struct siginfo info;
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struct ucontext uc;
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};
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struct frame_record {
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u64 fp;
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u64 lr;
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};
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struct rt_sigframe_user_layout {
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struct rt_sigframe __user *sigframe;
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struct frame_record __user *next_frame;
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unsigned long size; /* size of allocated sigframe data */
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unsigned long limit; /* largest allowed size */
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unsigned long fpsimd_offset;
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unsigned long esr_offset;
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unsigned long sve_offset;
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unsigned long extra_offset;
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unsigned long end_offset;
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};
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#define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
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#define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
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#define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
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static void init_user_layout(struct rt_sigframe_user_layout *user)
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{
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const size_t reserved_size =
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sizeof(user->sigframe->uc.uc_mcontext.__reserved);
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memset(user, 0, sizeof(*user));
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user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);
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user->limit = user->size + reserved_size;
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user->limit -= TERMINATOR_SIZE;
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user->limit -= EXTRA_CONTEXT_SIZE;
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/* Reserve space for extension and terminator ^ */
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}
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static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
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{
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return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
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}
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/*
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* Sanity limit on the approximate maximum size of signal frame we'll
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* try to generate. Stack alignment padding and the frame record are
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* not taken into account. This limit is not a guarantee and is
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* NOT ABI.
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*/
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#define SIGFRAME_MAXSZ SZ_64K
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static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
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unsigned long *offset, size_t size, bool extend)
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{
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size_t padded_size = round_up(size, 16);
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if (padded_size > user->limit - user->size &&
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!user->extra_offset &&
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extend) {
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int ret;
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user->limit += EXTRA_CONTEXT_SIZE;
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ret = __sigframe_alloc(user, &user->extra_offset,
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sizeof(struct extra_context), false);
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if (ret) {
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user->limit -= EXTRA_CONTEXT_SIZE;
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return ret;
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}
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/* Reserve space for the __reserved[] terminator */
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user->size += TERMINATOR_SIZE;
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/*
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* Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
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* the terminator:
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*/
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user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
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}
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/* Still not enough space? Bad luck! */
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if (padded_size > user->limit - user->size)
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return -ENOMEM;
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*offset = user->size;
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user->size += padded_size;
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return 0;
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}
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/*
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* Allocate space for an optional record of <size> bytes in the user
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* signal frame. The offset from the signal frame base address to the
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* allocated block is assigned to *offset.
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*/
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static int sigframe_alloc(struct rt_sigframe_user_layout *user,
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unsigned long *offset, size_t size)
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{
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return __sigframe_alloc(user, offset, size, true);
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}
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/* Allocate the null terminator record and prevent further allocations */
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static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
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{
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int ret;
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/* Un-reserve the space reserved for the terminator: */
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user->limit += TERMINATOR_SIZE;
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ret = sigframe_alloc(user, &user->end_offset,
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sizeof(struct _aarch64_ctx));
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if (ret)
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return ret;
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/* Prevent further allocation: */
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user->limit = user->size;
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return 0;
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}
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static void __user *apply_user_offset(
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struct rt_sigframe_user_layout const *user, unsigned long offset)
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{
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char __user *base = (char __user *)user->sigframe;
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return base + offset;
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}
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static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
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{
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struct user_fpsimd_state const *fpsimd =
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¤t->thread.uw.fpsimd_state;
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int err;
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/* copy the FP and status/control registers */
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err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
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__put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
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__put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
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/* copy the magic/size information */
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__put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
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__put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
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return err ? -EFAULT : 0;
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}
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static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
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{
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struct user_fpsimd_state fpsimd;
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__u32 magic, size;
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int err = 0;
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/* check the magic/size information */
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__get_user_error(magic, &ctx->head.magic, err);
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__get_user_error(size, &ctx->head.size, err);
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if (err)
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return -EFAULT;
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if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
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return -EINVAL;
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/* copy the FP and status/control registers */
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err = __copy_from_user(fpsimd.vregs, ctx->vregs,
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sizeof(fpsimd.vregs));
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__get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
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__get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
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clear_thread_flag(TIF_SVE);
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/* load the hardware registers from the fpsimd_state structure */
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if (!err)
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fpsimd_update_current_state(&fpsimd);
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return err ? -EFAULT : 0;
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}
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struct user_ctxs {
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struct fpsimd_context __user *fpsimd;
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struct sve_context __user *sve;
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};
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#ifdef CONFIG_ARM64_SVE
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static int preserve_sve_context(struct sve_context __user *ctx)
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{
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int err = 0;
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u16 reserved[ARRAY_SIZE(ctx->__reserved)];
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unsigned int vl = current->thread.sve_vl;
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unsigned int vq = 0;
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if (test_thread_flag(TIF_SVE))
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vq = sve_vq_from_vl(vl);
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memset(reserved, 0, sizeof(reserved));
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__put_user_error(SVE_MAGIC, &ctx->head.magic, err);
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__put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
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&ctx->head.size, err);
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__put_user_error(vl, &ctx->vl, err);
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BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
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err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
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if (vq) {
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/*
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* This assumes that the SVE state has already been saved to
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* the task struct by calling preserve_fpsimd_context().
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*/
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err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
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current->thread.sve_state,
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SVE_SIG_REGS_SIZE(vq));
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}
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return err ? -EFAULT : 0;
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}
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static int restore_sve_fpsimd_context(struct user_ctxs *user)
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{
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int err;
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unsigned int vq;
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struct user_fpsimd_state fpsimd;
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struct sve_context sve;
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if (__copy_from_user(&sve, user->sve, sizeof(sve)))
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return -EFAULT;
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if (sve.vl != current->thread.sve_vl)
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return -EINVAL;
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if (sve.head.size <= sizeof(*user->sve)) {
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clear_thread_flag(TIF_SVE);
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goto fpsimd_only;
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}
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vq = sve_vq_from_vl(sve.vl);
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if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq))
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return -EINVAL;
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/*
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* Careful: we are about __copy_from_user() directly into
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* thread.sve_state with preemption enabled, so protection is
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* needed to prevent a racing context switch from writing stale
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* registers back over the new data.
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*/
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fpsimd_flush_task_state(current);
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/* From now, fpsimd_thread_switch() won't touch thread.sve_state */
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sve_alloc(current);
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err = __copy_from_user(current->thread.sve_state,
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(char __user const *)user->sve +
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SVE_SIG_REGS_OFFSET,
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SVE_SIG_REGS_SIZE(vq));
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if (err)
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return -EFAULT;
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set_thread_flag(TIF_SVE);
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fpsimd_only:
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/* copy the FP and status/control registers */
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/* restore_sigframe() already checked that user->fpsimd != NULL. */
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err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
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sizeof(fpsimd.vregs));
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__get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
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__get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);
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/* load the hardware registers from the fpsimd_state structure */
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if (!err)
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fpsimd_update_current_state(&fpsimd);
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return err ? -EFAULT : 0;
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}
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#else /* ! CONFIG_ARM64_SVE */
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/* Turn any non-optimised out attempts to use these into a link error: */
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extern int preserve_sve_context(void __user *ctx);
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extern int restore_sve_fpsimd_context(struct user_ctxs *user);
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#endif /* ! CONFIG_ARM64_SVE */
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static int parse_user_sigframe(struct user_ctxs *user,
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struct rt_sigframe __user *sf)
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{
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struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
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struct _aarch64_ctx __user *head;
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char __user *base = (char __user *)&sc->__reserved;
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size_t offset = 0;
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size_t limit = sizeof(sc->__reserved);
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bool have_extra_context = false;
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char const __user *const sfp = (char const __user *)sf;
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user->fpsimd = NULL;
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user->sve = NULL;
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if (!IS_ALIGNED((unsigned long)base, 16))
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goto invalid;
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while (1) {
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int err = 0;
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u32 magic, size;
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char const __user *userp;
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struct extra_context const __user *extra;
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u64 extra_datap;
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u32 extra_size;
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struct _aarch64_ctx const __user *end;
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u32 end_magic, end_size;
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if (limit - offset < sizeof(*head))
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goto invalid;
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if (!IS_ALIGNED(offset, 16))
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goto invalid;
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head = (struct _aarch64_ctx __user *)(base + offset);
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__get_user_error(magic, &head->magic, err);
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__get_user_error(size, &head->size, err);
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if (err)
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return err;
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if (limit - offset < size)
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goto invalid;
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switch (magic) {
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case 0:
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if (size)
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goto invalid;
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goto done;
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case FPSIMD_MAGIC:
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if (!system_supports_fpsimd())
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goto invalid;
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if (user->fpsimd)
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goto invalid;
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if (size < sizeof(*user->fpsimd))
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goto invalid;
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user->fpsimd = (struct fpsimd_context __user *)head;
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break;
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case ESR_MAGIC:
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/* ignore */
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break;
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case SVE_MAGIC:
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if (!system_supports_sve())
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goto invalid;
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if (user->sve)
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goto invalid;
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if (size < sizeof(*user->sve))
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goto invalid;
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user->sve = (struct sve_context __user *)head;
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break;
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case EXTRA_MAGIC:
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if (have_extra_context)
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goto invalid;
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if (size < sizeof(*extra))
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goto invalid;
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userp = (char const __user *)head;
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extra = (struct extra_context const __user *)userp;
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userp += size;
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__get_user_error(extra_datap, &extra->datap, err);
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__get_user_error(extra_size, &extra->size, err);
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if (err)
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return err;
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/* Check for the dummy terminator in __reserved[]: */
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if (limit - offset - size < TERMINATOR_SIZE)
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goto invalid;
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end = (struct _aarch64_ctx const __user *)userp;
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userp += TERMINATOR_SIZE;
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__get_user_error(end_magic, &end->magic, err);
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__get_user_error(end_size, &end->size, err);
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if (err)
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return err;
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|
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if (end_magic || end_size)
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goto invalid;
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|
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/* Prevent looping/repeated parsing of extra_context */
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have_extra_context = true;
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base = (__force void __user *)extra_datap;
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if (!IS_ALIGNED((unsigned long)base, 16))
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goto invalid;
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if (!IS_ALIGNED(extra_size, 16))
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goto invalid;
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if (base != userp)
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goto invalid;
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|
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/* Reject "unreasonably large" frames: */
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if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
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goto invalid;
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/*
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* Ignore trailing terminator in __reserved[]
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* and start parsing extra data:
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*/
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offset = 0;
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limit = extra_size;
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if (!access_ok(base, limit))
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goto invalid;
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continue;
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|
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default:
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goto invalid;
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}
|
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|
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if (size < sizeof(*head))
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goto invalid;
|
|
|
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if (limit - offset < size)
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goto invalid;
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|
|
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offset += size;
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}
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done:
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return 0;
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invalid:
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return -EINVAL;
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}
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|
|
static int restore_sigframe(struct pt_regs *regs,
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struct rt_sigframe __user *sf)
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{
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sigset_t set;
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int i, err;
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struct user_ctxs user;
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err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
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if (err == 0)
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set_current_blocked(&set);
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for (i = 0; i < 31; i++)
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__get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
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err);
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__get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
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__get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
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__get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
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|
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/*
|
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* Avoid sys_rt_sigreturn() restarting.
|
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*/
|
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forget_syscall(regs);
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|
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err |= !valid_user_regs(®s->user_regs, current);
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if (err == 0)
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err = parse_user_sigframe(&user, sf);
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|
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if (err == 0 && system_supports_fpsimd()) {
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if (!user.fpsimd)
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return -EINVAL;
|
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|
|
if (user.sve) {
|
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if (!system_supports_sve())
|
|
return -EINVAL;
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|
|
err = restore_sve_fpsimd_context(&user);
|
|
} else {
|
|
err = restore_fpsimd_context(user.fpsimd);
|
|
}
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
SYSCALL_DEFINE0(rt_sigreturn)
|
|
{
|
|
struct pt_regs *regs = current_pt_regs();
|
|
struct rt_sigframe __user *frame;
|
|
|
|
/* Always make any pending restarted system calls return -EINTR */
|
|
current->restart_block.fn = do_no_restart_syscall;
|
|
|
|
/*
|
|
* Since we stacked the signal on a 128-bit boundary, then 'sp' should
|
|
* be word aligned here.
|
|
*/
|
|
if (regs->sp & 15)
|
|
goto badframe;
|
|
|
|
frame = (struct rt_sigframe __user *)regs->sp;
|
|
|
|
if (!access_ok(frame, sizeof (*frame)))
|
|
goto badframe;
|
|
|
|
if (restore_sigframe(regs, frame))
|
|
goto badframe;
|
|
|
|
if (restore_altstack(&frame->uc.uc_stack))
|
|
goto badframe;
|
|
|
|
return regs->regs[0];
|
|
|
|
badframe:
|
|
arm64_notify_segfault(regs->sp);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Determine the layout of optional records in the signal frame
|
|
*
|
|
* add_all: if true, lays out the biggest possible signal frame for
|
|
* this task; otherwise, generates a layout for the current state
|
|
* of the task.
|
|
*/
|
|
static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
|
|
bool add_all)
|
|
{
|
|
int err;
|
|
|
|
err = sigframe_alloc(user, &user->fpsimd_offset,
|
|
sizeof(struct fpsimd_context));
|
|
if (err)
|
|
return err;
|
|
|
|
/* fault information, if valid */
|
|
if (add_all || current->thread.fault_code) {
|
|
err = sigframe_alloc(user, &user->esr_offset,
|
|
sizeof(struct esr_context));
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
if (system_supports_sve()) {
|
|
unsigned int vq = 0;
|
|
|
|
if (add_all || test_thread_flag(TIF_SVE)) {
|
|
int vl = sve_max_vl;
|
|
|
|
if (!add_all)
|
|
vl = current->thread.sve_vl;
|
|
|
|
vq = sve_vq_from_vl(vl);
|
|
}
|
|
|
|
err = sigframe_alloc(user, &user->sve_offset,
|
|
SVE_SIG_CONTEXT_SIZE(vq));
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
return sigframe_alloc_end(user);
|
|
}
|
|
|
|
static int setup_sigframe(struct rt_sigframe_user_layout *user,
|
|
struct pt_regs *regs, sigset_t *set)
|
|
{
|
|
int i, err = 0;
|
|
struct rt_sigframe __user *sf = user->sigframe;
|
|
|
|
/* set up the stack frame for unwinding */
|
|
__put_user_error(regs->regs[29], &user->next_frame->fp, err);
|
|
__put_user_error(regs->regs[30], &user->next_frame->lr, err);
|
|
|
|
for (i = 0; i < 31; i++)
|
|
__put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
|
|
err);
|
|
__put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
|
|
__put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
|
|
__put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
|
|
|
|
__put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
|
|
|
|
err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
|
|
|
|
if (err == 0 && system_supports_fpsimd()) {
|
|
struct fpsimd_context __user *fpsimd_ctx =
|
|
apply_user_offset(user, user->fpsimd_offset);
|
|
err |= preserve_fpsimd_context(fpsimd_ctx);
|
|
}
|
|
|
|
/* fault information, if valid */
|
|
if (err == 0 && user->esr_offset) {
|
|
struct esr_context __user *esr_ctx =
|
|
apply_user_offset(user, user->esr_offset);
|
|
|
|
__put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
|
|
__put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
|
|
__put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
|
|
}
|
|
|
|
/* Scalable Vector Extension state, if present */
|
|
if (system_supports_sve() && err == 0 && user->sve_offset) {
|
|
struct sve_context __user *sve_ctx =
|
|
apply_user_offset(user, user->sve_offset);
|
|
err |= preserve_sve_context(sve_ctx);
|
|
}
|
|
|
|
if (err == 0 && user->extra_offset) {
|
|
char __user *sfp = (char __user *)user->sigframe;
|
|
char __user *userp =
|
|
apply_user_offset(user, user->extra_offset);
|
|
|
|
struct extra_context __user *extra;
|
|
struct _aarch64_ctx __user *end;
|
|
u64 extra_datap;
|
|
u32 extra_size;
|
|
|
|
extra = (struct extra_context __user *)userp;
|
|
userp += EXTRA_CONTEXT_SIZE;
|
|
|
|
end = (struct _aarch64_ctx __user *)userp;
|
|
userp += TERMINATOR_SIZE;
|
|
|
|
/*
|
|
* extra_datap is just written to the signal frame.
|
|
* The value gets cast back to a void __user *
|
|
* during sigreturn.
|
|
*/
|
|
extra_datap = (__force u64)userp;
|
|
extra_size = sfp + round_up(user->size, 16) - userp;
|
|
|
|
__put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
|
|
__put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
|
|
__put_user_error(extra_datap, &extra->datap, err);
|
|
__put_user_error(extra_size, &extra->size, err);
|
|
|
|
/* Add the terminator */
|
|
__put_user_error(0, &end->magic, err);
|
|
__put_user_error(0, &end->size, err);
|
|
}
|
|
|
|
/* set the "end" magic */
|
|
if (err == 0) {
|
|
struct _aarch64_ctx __user *end =
|
|
apply_user_offset(user, user->end_offset);
|
|
|
|
__put_user_error(0, &end->magic, err);
|
|
__put_user_error(0, &end->size, err);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
static int get_sigframe(struct rt_sigframe_user_layout *user,
|
|
struct ksignal *ksig, struct pt_regs *regs)
|
|
{
|
|
unsigned long sp, sp_top;
|
|
int err;
|
|
|
|
init_user_layout(user);
|
|
err = setup_sigframe_layout(user, false);
|
|
if (err)
|
|
return err;
|
|
|
|
sp = sp_top = sigsp(regs->sp, ksig);
|
|
|
|
sp = round_down(sp - sizeof(struct frame_record), 16);
|
|
user->next_frame = (struct frame_record __user *)sp;
|
|
|
|
sp = round_down(sp, 16) - sigframe_size(user);
|
|
user->sigframe = (struct rt_sigframe __user *)sp;
|
|
|
|
/*
|
|
* Check that we can actually write to the signal frame.
|
|
*/
|
|
if (!access_ok(user->sigframe, sp_top - sp))
|
|
return -EFAULT;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
|
|
struct rt_sigframe_user_layout *user, int usig)
|
|
{
|
|
__sigrestore_t sigtramp;
|
|
|
|
regs->regs[0] = usig;
|
|
regs->sp = (unsigned long)user->sigframe;
|
|
regs->regs[29] = (unsigned long)&user->next_frame->fp;
|
|
regs->pc = (unsigned long)ka->sa.sa_handler;
|
|
|
|
/*
|
|
* Signal delivery is a (wacky) indirect function call in
|
|
* userspace, so simulate the same setting of BTYPE as a BLR
|
|
* <register containing the signal handler entry point>.
|
|
* Signal delivery to a location in a PROT_BTI guarded page
|
|
* that is not a function entry point will now trigger a
|
|
* SIGILL in userspace.
|
|
*
|
|
* If the signal handler entry point is not in a PROT_BTI
|
|
* guarded page, this is harmless.
|
|
*/
|
|
if (system_supports_bti()) {
|
|
regs->pstate &= ~PSR_BTYPE_MASK;
|
|
regs->pstate |= PSR_BTYPE_C;
|
|
}
|
|
|
|
if (ka->sa.sa_flags & SA_RESTORER)
|
|
sigtramp = ka->sa.sa_restorer;
|
|
else
|
|
sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
|
|
|
|
regs->regs[30] = (unsigned long)sigtramp;
|
|
}
|
|
|
|
static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
|
|
struct pt_regs *regs)
|
|
{
|
|
struct rt_sigframe_user_layout user;
|
|
struct rt_sigframe __user *frame;
|
|
int err = 0;
|
|
|
|
fpsimd_signal_preserve_current_state();
|
|
|
|
if (get_sigframe(&user, ksig, regs))
|
|
return 1;
|
|
|
|
frame = user.sigframe;
|
|
|
|
__put_user_error(0, &frame->uc.uc_flags, err);
|
|
__put_user_error(NULL, &frame->uc.uc_link, err);
|
|
|
|
err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
|
|
err |= setup_sigframe(&user, regs, set);
|
|
if (err == 0) {
|
|
setup_return(regs, &ksig->ka, &user, usig);
|
|
if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
|
|
err |= copy_siginfo_to_user(&frame->info, &ksig->info);
|
|
regs->regs[1] = (unsigned long)&frame->info;
|
|
regs->regs[2] = (unsigned long)&frame->uc;
|
|
}
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
static void setup_restart_syscall(struct pt_regs *regs)
|
|
{
|
|
if (is_compat_task())
|
|
compat_setup_restart_syscall(regs);
|
|
else
|
|
regs->regs[8] = __NR_restart_syscall;
|
|
}
|
|
|
|
/*
|
|
* OK, we're invoking a handler
|
|
*/
|
|
static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
|
|
{
|
|
sigset_t *oldset = sigmask_to_save();
|
|
int usig = ksig->sig;
|
|
int ret;
|
|
|
|
rseq_signal_deliver(ksig, regs);
|
|
|
|
/*
|
|
* Set up the stack frame
|
|
*/
|
|
if (is_compat_task()) {
|
|
if (ksig->ka.sa.sa_flags & SA_SIGINFO)
|
|
ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
|
|
else
|
|
ret = compat_setup_frame(usig, ksig, oldset, regs);
|
|
} else {
|
|
ret = setup_rt_frame(usig, ksig, oldset, regs);
|
|
}
|
|
|
|
/*
|
|
* Check that the resulting registers are actually sane.
|
|
*/
|
|
ret |= !valid_user_regs(®s->user_regs, current);
|
|
|
|
/* Step into the signal handler if we are stepping */
|
|
signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
|
|
}
|
|
|
|
/*
|
|
* Note that 'init' is a special process: it doesn't get signals it doesn't
|
|
* want to handle. Thus you cannot kill init even with a SIGKILL even by
|
|
* mistake.
|
|
*
|
|
* Note that we go through the signals twice: once to check the signals that
|
|
* the kernel can handle, and then we build all the user-level signal handling
|
|
* stack-frames in one go after that.
|
|
*/
|
|
static void do_signal(struct pt_regs *regs)
|
|
{
|
|
unsigned long continue_addr = 0, restart_addr = 0;
|
|
int retval = 0;
|
|
struct ksignal ksig;
|
|
bool syscall = in_syscall(regs);
|
|
|
|
/*
|
|
* If we were from a system call, check for system call restarting...
|
|
*/
|
|
if (syscall) {
|
|
continue_addr = regs->pc;
|
|
restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
|
|
retval = regs->regs[0];
|
|
|
|
/*
|
|
* Avoid additional syscall restarting via ret_to_user.
|
|
*/
|
|
forget_syscall(regs);
|
|
|
|
/*
|
|
* Prepare for system call restart. We do this here so that a
|
|
* debugger will see the already changed PC.
|
|
*/
|
|
switch (retval) {
|
|
case -ERESTARTNOHAND:
|
|
case -ERESTARTSYS:
|
|
case -ERESTARTNOINTR:
|
|
case -ERESTART_RESTARTBLOCK:
|
|
regs->regs[0] = regs->orig_x0;
|
|
regs->pc = restart_addr;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Get the signal to deliver. When running under ptrace, at this point
|
|
* the debugger may change all of our registers.
|
|
*/
|
|
if (get_signal(&ksig)) {
|
|
/*
|
|
* Depending on the signal settings, we may need to revert the
|
|
* decision to restart the system call, but skip this if a
|
|
* debugger has chosen to restart at a different PC.
|
|
*/
|
|
if (regs->pc == restart_addr &&
|
|
(retval == -ERESTARTNOHAND ||
|
|
retval == -ERESTART_RESTARTBLOCK ||
|
|
(retval == -ERESTARTSYS &&
|
|
!(ksig.ka.sa.sa_flags & SA_RESTART)))) {
|
|
regs->regs[0] = -EINTR;
|
|
regs->pc = continue_addr;
|
|
}
|
|
|
|
handle_signal(&ksig, regs);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Handle restarting a different system call. As above, if a debugger
|
|
* has chosen to restart at a different PC, ignore the restart.
|
|
*/
|
|
if (syscall && regs->pc == restart_addr) {
|
|
if (retval == -ERESTART_RESTARTBLOCK)
|
|
setup_restart_syscall(regs);
|
|
user_rewind_single_step(current);
|
|
}
|
|
|
|
restore_saved_sigmask();
|
|
}
|
|
|
|
asmlinkage void do_notify_resume(struct pt_regs *regs,
|
|
unsigned long thread_flags)
|
|
{
|
|
/*
|
|
* The assembly code enters us with IRQs off, but it hasn't
|
|
* informed the tracing code of that for efficiency reasons.
|
|
* Update the trace code with the current status.
|
|
*/
|
|
trace_hardirqs_off();
|
|
|
|
do {
|
|
/* Check valid user FS if needed */
|
|
addr_limit_user_check();
|
|
|
|
if (thread_flags & _TIF_NEED_RESCHED) {
|
|
/* Unmask Debug and SError for the next task */
|
|
local_daif_restore(DAIF_PROCCTX_NOIRQ);
|
|
|
|
schedule();
|
|
} else {
|
|
local_daif_restore(DAIF_PROCCTX);
|
|
|
|
if (thread_flags & _TIF_UPROBE)
|
|
uprobe_notify_resume(regs);
|
|
|
|
if (thread_flags & _TIF_SIGPENDING)
|
|
do_signal(regs);
|
|
|
|
if (thread_flags & _TIF_NOTIFY_RESUME) {
|
|
clear_thread_flag(TIF_NOTIFY_RESUME);
|
|
tracehook_notify_resume(regs);
|
|
rseq_handle_notify_resume(NULL, regs);
|
|
}
|
|
|
|
if (thread_flags & _TIF_FOREIGN_FPSTATE)
|
|
fpsimd_restore_current_state();
|
|
}
|
|
|
|
local_daif_mask();
|
|
thread_flags = READ_ONCE(current_thread_info()->flags);
|
|
} while (thread_flags & _TIF_WORK_MASK);
|
|
}
|
|
|
|
unsigned long __ro_after_init signal_minsigstksz;
|
|
|
|
/*
|
|
* Determine the stack space required for guaranteed signal devliery.
|
|
* This function is used to populate AT_MINSIGSTKSZ at process startup.
|
|
* cpufeatures setup is assumed to be complete.
|
|
*/
|
|
void __init minsigstksz_setup(void)
|
|
{
|
|
struct rt_sigframe_user_layout user;
|
|
|
|
init_user_layout(&user);
|
|
|
|
/*
|
|
* If this fails, SIGFRAME_MAXSZ needs to be enlarged. It won't
|
|
* be big enough, but it's our best guess:
|
|
*/
|
|
if (WARN_ON(setup_sigframe_layout(&user, true)))
|
|
return;
|
|
|
|
signal_minsigstksz = sigframe_size(&user) +
|
|
round_up(sizeof(struct frame_record), 16) +
|
|
16; /* max alignment padding */
|
|
}
|