From mboxrd@z Thu Jan 1 00:00:00 1970 From: T.E.Baldwin99@members.leeds.ac.uk (Timothy E Baldwin) Date: Sat, 3 Feb 2018 15:21:12 +0000 Subject: [PATCH] ARM: Call syscall_trace_exit even when system call skipped Message-ID: <20180203152112.2449-1-T.E.Baldwin99@members.leeds.ac.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On at least x86 and ARM64, and as documented in the ptrace man page a skipped system call will still cause a syscall exit ptrace stop. Previous to this commit 32-bit ARM did not, resulting in strace being confused when seccomp skips system calls. This change also impacts programs that use ptrace to skip system calls. Fixes: ad75b51459ae ("ARM: 7579/1: arch/allow a scno of -1 to not cause a SIGILL") Signed-off-by: Timothy E Baldwin --- arch/arm/kernel/entry-common.S | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 99c908226065..88a65157307d 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -288,16 +288,15 @@ __sys_trace: cmp scno, #-1 @ skip the syscall? bne 2b add sp, sp, #S_OFF @ restore stack - b ret_slow_syscall -__sys_trace_return: - str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 +__sys_trace_return_nosave: + enable_irq_notrace mov r0, sp bl syscall_trace_exit b ret_slow_syscall -__sys_trace_return_nosave: - enable_irq_notrace +__sys_trace_return: + str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 mov r0, sp bl syscall_trace_exit b ret_slow_syscall -- 2.14.2