From 4f32a39d49b25eaa66d2420f1f03d371ea4cd906 Mon Sep 17 00:00:00 2001 From: James Hogan Date: Thu, 29 Jun 2017 10:12:34 +0100 Subject: [PATCH] MIPS: Negate error syscall return in trace The sys_exit trace event takes a single return value for the system call, which MIPS passes the value of the $v0 (result) register, however MIPS returns positive error codes in $v0 with $a3 specifying that $v0 contains an error code. As a result erroring system calls are traced returning positive error numbers that can't always be distinguished from success. Use regs_return_value() to negate the error code if $a3 is set. Fixes: 1d7bf993e073 ("MIPS: ftrace: Add support for syscall tracepoints.") Signed-off-by: James Hogan Cc: Steven Rostedt Cc: Ingo Molnar Cc: linux-mips@linux-mips.org Cc: # 3.13+ Patchwork: https://patchwork.linux-mips.org/patch/16651/ Acked-by: Steven Rostedt (VMware) Signed-off-by: Ralf Baechle --- arch/mips/kernel/ptrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c index ba3b1f771256f..8e2ea86dc23e8 100644 --- a/arch/mips/kernel/ptrace.c +++ b/arch/mips/kernel/ptrace.c @@ -913,7 +913,7 @@ asmlinkage void syscall_trace_leave(struct pt_regs *regs) audit_syscall_exit(regs); if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT))) - trace_sys_exit(regs, regs->regs[2]); + trace_sys_exit(regs, regs_return_value(regs)); if (test_thread_flag(TIF_SYSCALL_TRACE)) tracehook_report_syscall_exit(regs, 0); -- 2.39.5