mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-06 02:24:14 +08:00
637ec831ea
The Memory Tagging Extension has two modes of notifying a tag check fault at EL0, configurable through the SCTLR_EL1.TCF0 field: 1. Synchronous raising of a Data Abort exception with DFSC 17. 2. Asynchronous setting of a cumulative bit in TFSRE0_EL1. Add the exception handler for the synchronous exception and handling of the asynchronous TFSRE0_EL1.TF0 bit setting via a new TIF flag in do_notify_resume(). On a tag check failure in user-space, whether synchronous or asynchronous, a SIGSEGV will be raised on the faulting thread. Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Co-developed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org>
215 lines
5.8 KiB
C
215 lines
5.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
|
|
#include <linux/compiler.h>
|
|
#include <linux/context_tracking.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/nospec.h>
|
|
#include <linux/ptrace.h>
|
|
#include <linux/syscalls.h>
|
|
|
|
#include <asm/daifflags.h>
|
|
#include <asm/debug-monitors.h>
|
|
#include <asm/fpsimd.h>
|
|
#include <asm/syscall.h>
|
|
#include <asm/thread_info.h>
|
|
#include <asm/unistd.h>
|
|
|
|
long compat_arm_syscall(struct pt_regs *regs, int scno);
|
|
long sys_ni_syscall(void);
|
|
|
|
static long do_ni_syscall(struct pt_regs *regs, int scno)
|
|
{
|
|
#ifdef CONFIG_COMPAT
|
|
long ret;
|
|
if (is_compat_task()) {
|
|
ret = compat_arm_syscall(regs, scno);
|
|
if (ret != -ENOSYS)
|
|
return ret;
|
|
}
|
|
#endif
|
|
|
|
return sys_ni_syscall();
|
|
}
|
|
|
|
static long __invoke_syscall(struct pt_regs *regs, syscall_fn_t syscall_fn)
|
|
{
|
|
return syscall_fn(regs);
|
|
}
|
|
|
|
static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
|
|
unsigned int sc_nr,
|
|
const syscall_fn_t syscall_table[])
|
|
{
|
|
long ret;
|
|
|
|
if (scno < sc_nr) {
|
|
syscall_fn_t syscall_fn;
|
|
syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)];
|
|
ret = __invoke_syscall(regs, syscall_fn);
|
|
} else {
|
|
ret = do_ni_syscall(regs, scno);
|
|
}
|
|
|
|
if (is_compat_task())
|
|
ret = lower_32_bits(ret);
|
|
|
|
regs->regs[0] = ret;
|
|
}
|
|
|
|
static inline bool has_syscall_work(unsigned long flags)
|
|
{
|
|
return unlikely(flags & _TIF_SYSCALL_WORK);
|
|
}
|
|
|
|
int syscall_trace_enter(struct pt_regs *regs);
|
|
void syscall_trace_exit(struct pt_regs *regs);
|
|
|
|
#ifdef CONFIG_ARM64_ERRATUM_1463225
|
|
DECLARE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa);
|
|
|
|
static void cortex_a76_erratum_1463225_svc_handler(void)
|
|
{
|
|
u32 reg, val;
|
|
|
|
if (!unlikely(test_thread_flag(TIF_SINGLESTEP)))
|
|
return;
|
|
|
|
if (!unlikely(this_cpu_has_cap(ARM64_WORKAROUND_1463225)))
|
|
return;
|
|
|
|
__this_cpu_write(__in_cortex_a76_erratum_1463225_wa, 1);
|
|
reg = read_sysreg(mdscr_el1);
|
|
val = reg | DBG_MDSCR_SS | DBG_MDSCR_KDE;
|
|
write_sysreg(val, mdscr_el1);
|
|
asm volatile("msr daifclr, #8");
|
|
isb();
|
|
|
|
/* We will have taken a single-step exception by this point */
|
|
|
|
write_sysreg(reg, mdscr_el1);
|
|
__this_cpu_write(__in_cortex_a76_erratum_1463225_wa, 0);
|
|
}
|
|
#else
|
|
static void cortex_a76_erratum_1463225_svc_handler(void) { }
|
|
#endif /* CONFIG_ARM64_ERRATUM_1463225 */
|
|
|
|
static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
|
|
const syscall_fn_t syscall_table[])
|
|
{
|
|
unsigned long flags = current_thread_info()->flags;
|
|
|
|
regs->orig_x0 = regs->regs[0];
|
|
regs->syscallno = scno;
|
|
|
|
/*
|
|
* BTI note:
|
|
* The architecture does not guarantee that SPSR.BTYPE is zero
|
|
* on taking an SVC, so we could return to userspace with a
|
|
* non-zero BTYPE after the syscall.
|
|
*
|
|
* This shouldn't matter except when userspace is explicitly
|
|
* doing something stupid, such as setting PROT_BTI on a page
|
|
* that lacks conforming BTI/PACIxSP instructions, falling
|
|
* through from one executable page to another with differing
|
|
* PROT_BTI, or messing with BTYPE via ptrace: in such cases,
|
|
* userspace should not be surprised if a SIGILL occurs on
|
|
* syscall return.
|
|
*
|
|
* So, don't touch regs->pstate & PSR_BTYPE_MASK here.
|
|
* (Similarly for HVC and SMC elsewhere.)
|
|
*/
|
|
|
|
cortex_a76_erratum_1463225_svc_handler();
|
|
local_daif_restore(DAIF_PROCCTX);
|
|
user_exit();
|
|
|
|
if (system_supports_mte() && (flags & _TIF_MTE_ASYNC_FAULT)) {
|
|
/*
|
|
* Process the asynchronous tag check fault before the actual
|
|
* syscall. do_notify_resume() will send a signal to userspace
|
|
* before the syscall is restarted.
|
|
*/
|
|
regs->regs[0] = -ERESTARTNOINTR;
|
|
return;
|
|
}
|
|
|
|
if (has_syscall_work(flags)) {
|
|
/*
|
|
* The de-facto standard way to skip a system call using ptrace
|
|
* is to set the system call to -1 (NO_SYSCALL) and set x0 to a
|
|
* suitable error code for consumption by userspace. However,
|
|
* this cannot be distinguished from a user-issued syscall(-1)
|
|
* and so we must set x0 to -ENOSYS here in case the tracer doesn't
|
|
* issue the skip and we fall into trace_exit with x0 preserved.
|
|
*
|
|
* This is slightly odd because it also means that if a tracer
|
|
* sets the system call number to -1 but does not initialise x0,
|
|
* then x0 will be preserved for all system calls apart from a
|
|
* user-issued syscall(-1). However, requesting a skip and not
|
|
* setting the return value is unlikely to do anything sensible
|
|
* anyway.
|
|
*/
|
|
if (scno == NO_SYSCALL)
|
|
regs->regs[0] = -ENOSYS;
|
|
scno = syscall_trace_enter(regs);
|
|
if (scno == NO_SYSCALL)
|
|
goto trace_exit;
|
|
}
|
|
|
|
invoke_syscall(regs, scno, sc_nr, syscall_table);
|
|
|
|
/*
|
|
* The tracing status may have changed under our feet, so we have to
|
|
* check again. However, if we were tracing entry, then we always trace
|
|
* exit regardless, as the old entry assembly did.
|
|
*/
|
|
if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
|
|
local_daif_mask();
|
|
flags = current_thread_info()->flags;
|
|
if (!has_syscall_work(flags) && !(flags & _TIF_SINGLESTEP)) {
|
|
/*
|
|
* We're off to userspace, where interrupts are
|
|
* always enabled after we restore the flags from
|
|
* the SPSR.
|
|
*/
|
|
trace_hardirqs_on();
|
|
return;
|
|
}
|
|
local_daif_restore(DAIF_PROCCTX);
|
|
}
|
|
|
|
trace_exit:
|
|
syscall_trace_exit(regs);
|
|
}
|
|
|
|
static inline void sve_user_discard(void)
|
|
{
|
|
if (!system_supports_sve())
|
|
return;
|
|
|
|
clear_thread_flag(TIF_SVE);
|
|
|
|
/*
|
|
* task_fpsimd_load() won't be called to update CPACR_EL1 in
|
|
* ret_to_user unless TIF_FOREIGN_FPSTATE is still set, which only
|
|
* happens if a context switch or kernel_neon_begin() or context
|
|
* modification (sigreturn, ptrace) intervenes.
|
|
* So, ensure that CPACR_EL1 is already correct for the fast-path case.
|
|
*/
|
|
sve_user_disable();
|
|
}
|
|
|
|
void do_el0_svc(struct pt_regs *regs)
|
|
{
|
|
sve_user_discard();
|
|
el0_svc_common(regs, regs->regs[8], __NR_syscalls, sys_call_table);
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
void do_el0_svc_compat(struct pt_regs *regs)
|
|
{
|
|
el0_svc_common(regs, regs->regs[7], __NR_compat_syscalls,
|
|
compat_sys_call_table);
|
|
}
|
|
#endif
|