| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 56/83] MIPS: Negate error syscall return in trace | Date | Tue, 25 Jul 2017 12:19:20 -0700 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: James Hogan <james.hogan@imgtec.com>
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: 1d7bf993e073 ("MIPS: ftrace: Add support for syscall tracepoints.") Signed-off-by: James 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: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- 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 @@ -927,7 +927,7 @@ 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);
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