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Message-Id: <1436945834-26660-2-git-send-email-mpe@ellerman.id.au> Date: Wed, 15 Jul 2015 17:37:04 +1000 From: Michael Ellerman <mpe@...erman.id.au> To: <linuxppc-dev@...abs.org> Cc: <linux-kernel@...r.kernel.org>, keescook@...omium.org, luto@...capital.net, wad@...omium.org, strosake@...ux.vnet.ibm.com, bogdan.purcareata@...escale.com Subject: [RFC PATCH 02/12] 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 ... Signed-off-by: Michael Ellerman <mpe@...erman.id.au> --- 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 8c145fd17d86..e8b6b5f7de7c 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 46fc0f4d8982..67ecdf61f4e3 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -20,6 +20,7 @@ */ #include <linux/errno.h> +#include <linux/err.h> #include <linux/sys.h> #include <linux/threads.h> #include <asm/reg.h> @@ -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 0796c487d3db..8292581a42f1 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -19,6 +19,7 @@ */ #include <linux/errno.h> +#include <linux/err.h> #include <asm/unistd.h> #include <asm/processor.h> #include <asm/page.h> @@ -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 @@ -279,7 +280,7 @@ 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 -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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