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efd112353b
We always run userspace with interrupts enabled, but with the recent
conversion of the syscall entry/exit code to C, we don't inform the
hardirq tracing code that interrupts are about to become enabled by
virtue of restoring the EL0 SPSR.
This patch ensures that trace_hardirqs_on() is called on the syscall
return path when we return to the assembly code with interrupts still
disabled.
Fixes: f37099b699 ("arm64: convert syscall trace logic to C")
Reported-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
140 lines
3.2 KiB
C
140 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/compiler.h>
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#include <linux/context_tracking.h>
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#include <linux/errno.h>
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#include <linux/nospec.h>
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#include <linux/ptrace.h>
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#include <linux/syscalls.h>
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#include <asm/daifflags.h>
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#include <asm/fpsimd.h>
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#include <asm/syscall.h>
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#include <asm/thread_info.h>
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#include <asm/unistd.h>
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long compat_arm_syscall(struct pt_regs *regs);
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long sys_ni_syscall(void);
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asmlinkage long do_ni_syscall(struct pt_regs *regs)
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{
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#ifdef CONFIG_COMPAT
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long ret;
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if (is_compat_task()) {
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ret = compat_arm_syscall(regs);
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if (ret != -ENOSYS)
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return ret;
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}
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#endif
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return sys_ni_syscall();
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}
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static long __invoke_syscall(struct pt_regs *regs, syscall_fn_t syscall_fn)
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{
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return syscall_fn(regs);
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}
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static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
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unsigned int sc_nr,
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const syscall_fn_t syscall_table[])
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{
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long ret;
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if (scno < sc_nr) {
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syscall_fn_t syscall_fn;
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syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)];
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ret = __invoke_syscall(regs, syscall_fn);
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} else {
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ret = do_ni_syscall(regs);
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}
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regs->regs[0] = ret;
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}
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static inline bool has_syscall_work(unsigned long flags)
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{
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return unlikely(flags & _TIF_SYSCALL_WORK);
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}
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int syscall_trace_enter(struct pt_regs *regs);
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void syscall_trace_exit(struct pt_regs *regs);
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static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
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const syscall_fn_t syscall_table[])
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{
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unsigned long flags = current_thread_info()->flags;
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regs->orig_x0 = regs->regs[0];
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regs->syscallno = scno;
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local_daif_restore(DAIF_PROCCTX);
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user_exit();
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if (has_syscall_work(flags)) {
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/* set default errno for user-issued syscall(-1) */
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if (scno == NO_SYSCALL)
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regs->regs[0] = -ENOSYS;
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scno = syscall_trace_enter(regs);
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if (scno == NO_SYSCALL)
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goto trace_exit;
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}
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invoke_syscall(regs, scno, sc_nr, syscall_table);
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/*
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* The tracing status may have changed under our feet, so we have to
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* check again. However, if we were tracing entry, then we always trace
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* exit regardless, as the old entry assembly did.
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*/
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if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
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local_daif_mask();
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flags = current_thread_info()->flags;
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if (!has_syscall_work(flags)) {
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/*
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* We're off to userspace, where interrupts are
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* always enabled after we restore the flags from
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* the SPSR.
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*/
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trace_hardirqs_on();
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return;
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}
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local_daif_restore(DAIF_PROCCTX);
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}
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trace_exit:
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syscall_trace_exit(regs);
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}
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static inline void sve_user_discard(void)
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{
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if (!system_supports_sve())
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return;
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clear_thread_flag(TIF_SVE);
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/*
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* task_fpsimd_load() won't be called to update CPACR_EL1 in
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* ret_to_user unless TIF_FOREIGN_FPSTATE is still set, which only
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* happens if a context switch or kernel_neon_begin() or context
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* modification (sigreturn, ptrace) intervenes.
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* So, ensure that CPACR_EL1 is already correct for the fast-path case.
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*/
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sve_user_disable();
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}
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asmlinkage void el0_svc_handler(struct pt_regs *regs)
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{
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sve_user_discard();
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el0_svc_common(regs, regs->regs[8], __NR_syscalls, sys_call_table);
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}
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#ifdef CONFIG_COMPAT
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asmlinkage void el0_svc_compat_handler(struct pt_regs *regs)
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{
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el0_svc_common(regs, regs->regs[7], __NR_compat_syscalls,
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compat_sys_call_table);
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}
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#endif
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