Patch "MIPS: Negate error syscall return in trace" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

MIPS: Negate error syscall return in trace

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mips-negate-error-syscall-return-in-trace.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: James Hogan <[email protected]>
Date: Thu, 29 Jun 2017 10:12:34 +0100
Subject: MIPS: Negate error syscall return in trace

From: James Hogan <[email protected]>

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.

Patchwork: https://patchwork.linux-mips.org/patch/16651/

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

@@ -924,7 +924,7 @@ asmlinkage void syscall_trace_leave(stru
 	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);

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/mips-send-sigill-for-bposge32-in-__compute_return_epc_for_insn.patch queue-4.9/mips-actually-decode-jalx-in-__compute_return_epc_for_insn.patch queue-4.9/mips-fix-mips_atomic_set-retry-condition.patch queue-4.9/mips-fix-a-typo-s-preset-present-in-r2-to-r6-emulation-error-message.patch queue-4.9/mips-fix-mips_atomic_set-with-eva.patch queue-4.9/mips-save-static-registers-before-sysmips.patch queue-4.9/mips-fix-unaligned-pc-interpretation-in-compute_return_epc.patch queue-4.9/mips-fix-mips-i-isa-proc-cpuinfo-reporting.patch queue-4.9/mips-rename-sigill_r6-to-sigill_r2r6-in-__compute_return_epc_for_insn.patch queue-4.9/mips-negate-error-syscall-return-in-trace.patch queue-4.9/mips-send-sigill-for-r6-branches-in-__compute_return_epc_for_insn.patch queue-4.9/mips-send-sigill-for-linked-branches-in-__compute_return_epc_for_insn.patch queue-4.9/mips-math-emu-prevent-wrong-isa-mode-instruction-emulation.patch