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Commit 02131aea authored by James Hogan's avatar James Hogan Committed by Greg Kroah-Hartman
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MIPS: Negate error syscall return in trace 



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
success.

Use regs_return_value() to negate the error code if $a3 is set.

Fixes: 1d7bf993 ("MIPS: ftrace: Add support for syscall tracepoints.")
Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16651/


Acked-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f39f3b5d

arch/mips/kernel/ptrace.c

+1 −1
Original line number Diff line number Diff line
@@ -924,7 +924,7 @@ 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);