From 1b1a3702a65c1a6511e4c95ecb3770dfdf235bcf Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 23 Jul 2015 20:21:04 +1000 Subject: [PATCH] powerpc: Don't negate error in syscall_set_return_value() Currently the only caller of syscall_set_return_value() is seccomp filter, which is not enabled on powerpc. This means we have not noticed that our implementation of syscall_set_return_value() negates error, even though the value passed in is already negative. So remove the negation in syscall_set_return_value(), and expect the caller to do it like all other implementations do. Also add a comment about the ccr handling. Signed-off-by: Michael Ellerman Reviewed-by: Kees Cook --- arch/powerpc/include/asm/syscall.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h index c6239dabcfb1..cabe90133e69 100644 --- a/arch/powerpc/include/asm/syscall.h +++ b/arch/powerpc/include/asm/syscall.h @@ -44,9 +44,15 @@ static inline void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs, int error, long val) { + /* + * In the general case it's not obvious that we must deal with CCR + * here, as the syscall exit path will also do that for us. However + * there are some places, eg. the signal code, which check ccr to + * decide if the value in r3 is actually an error. + */ if (error) { regs->ccr |= 0x10000000L; - regs->gpr[3] = -error; + regs->gpr[3] = error; } else { regs->ccr &= ~0x10000000L; regs->gpr[3] = val; -- 2.39.5