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Subject[PATCH 4.12 126/196] MIPS: Negate error syscall return in trace
4.12-stable review patch.  If anyone has any objections, please let me know.


From: James Hogan <>

commit 4f32a39d49b25eaa66d2420f1f03d371ea4cd906 upstream.

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

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 <>
Acked-by: Steven Rostedt (VMware) <>
Signed-off-by: Ralf Baechle <>
Signed-off-by: Greg Kroah-Hartman <>

arch/mips/kernel/ptrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -895,7 +895,7 @@ asmlinkage void syscall_trace_leave(stru

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);

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