From c3525940cca53cf3568fefd35d169fea4f107f0a Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 23 Jul 2015 20:21:01 +1000 Subject: [PATCH] powerpc/kernel: Switch to using MAX_ERRNO Currently on powerpc we have our own #define for the highest (negative) errno value, called _LAST_ERRNO. This is defined to be 516, for reasons which are not clear. The generic code, and x86, use MAX_ERRNO, which is defined to be 4095. In particular seccomp uses MAX_ERRNO to restrict the value that a seccomp filter can return. Currently with the mismatch between _LAST_ERRNO and MAX_ERRNO, a seccomp tracer wanting to return 600, expecting it to be seen as an error, would instead find on powerpc that userspace sees a successful syscall with a return value of 600. To avoid this inconsistency, switch powerpc to use MAX_ERRNO. We are somewhat confident that generic syscalls that can return a non-error value above negative MAX_ERRNO have already been updated to use force_successful_syscall_return(). I have also checked all the powerpc specific syscalls, and believe that none of them expect to return a non-error value between -MAX_ERRNO and -516. So this change should be safe ... Acked-by: Benjamin Herrenschmidt Signed-off-by: Michael Ellerman Reviewed-by: Kees Cook --- arch/powerpc/include/uapi/asm/errno.h | 2 -- arch/powerpc/kernel/entry_32.S | 3 ++- arch/powerpc/kernel/entry_64.S | 5 +++-- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/include/uapi/asm/errno.h b/arch/powerpc/include/uapi/asm/errno.h index 8c145fd..e8b6b5f 100644 --- a/arch/powerpc/include/uapi/asm/errno.h +++ b/arch/powerpc/include/uapi/asm/errno.h @@ -6,6 +6,4 @@ #undef EDEADLOCK #define EDEADLOCK 58 /* File locking deadlock error */ -#define _LAST_ERRNO 516 - #endif /* _ASM_POWERPC_ERRNO_H */ diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index 46fc0f4..67ecdf6 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -20,6 +20,7 @@ */ #include +#include #include #include #include @@ -354,7 +355,7 @@ ret_from_syscall: SYNC MTMSRD(r10) lwz r9,TI_FLAGS(r12) - li r8,-_LAST_ERRNO + li r8,-MAX_ERRNO andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK) bne- syscall_exit_work cmplw 0,r3,r8 diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 579e0f9..ee15d3c 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -19,6 +19,7 @@ */ #include +#include #include #include #include @@ -207,7 +208,7 @@ system_call: /* label this so stack traces look sane */ #endif /* CONFIG_PPC_BOOK3E */ ld r9,TI_FLAGS(r12) - li r11,-_LAST_ERRNO + li r11,-MAX_ERRNO andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK) bne- syscall_exit_work cmpld r3,r11 @@ -277,7 +278,7 @@ syscall_exit_work: beq+ 0f REST_NVGPRS(r1) b 2f -0: cmpld r3,r11 /* r10 is -LAST_ERRNO */ +0: cmpld r3,r11 /* r11 is -MAX_ERRNO */ blt+ 1f andi. r0,r9,_TIF_NOERROR bne- 1f -- 2.7.4