From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Eric W. Biederman" Subject: [PATCH 1/7] signal/alpha: Document a conflict with SI_USER for SIGTRAP Date: Tue, 18 Jul 2017 09:06:45 -0500 Message-ID: <20170718140651.15973-1-ebiederm@xmission.com> References: <87o9shg7t7.fsf_-_@xmission.com> Return-path: In-Reply-To: <87o9shg7t7.fsf_-_@xmission.com> Sender: linux-arch-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Andy Lutomirski , Linus Torvalds , Al Viro , Oleg Nesterov , Andrei Vagin , Thomas Gleixner , Greg KH , Andrey Vagin , Serge Hallyn , Pavel Emelyanov , Cyrill Gorcunov , Peter Zijlstra , Willy Tarreau , linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Linux Containers , Michael Kerrisk , "Eric W. Biederman" , Helge Deller , Richard Henderson , Ivan Kokshaysky List-Id: linux-api@vger.kernel.org Setting si_code to __SI_FAULT results in a userspace seeing an si_code of 0. This is the same si_code as SI_USER. Posix and common sense requires that SI_USER not be a signal specific si_code. As such this use of 0 for the si_code is a pretty horribly broken ABI. Given that alpha is on it's last legs I don't know that it is worth fixing this, but it is worth documenting what is going on so that no one decides to copy this bad decision. This was introduced during the 2.5 development cycle so this mess has had a long time for people to be able to depend upon it. v2: Added FPE_FIXME for alpha as Helge Deller pointed out with his alternate patch one of the cases is SIGFPE not SIGTRAP. Cc: Helge Deller Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Matt Turner Cc: linux-alpha@vger.kernel.org History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git Ref: 0a635c7a84cf ("Fill in siginfo_t.") Signed-off-by: "Eric W. Biederman" --- arch/alpha/include/uapi/asm/siginfo.h | 14 ++++++++++++++ arch/alpha/kernel/traps.c | 6 +++--- 2 files changed, 17 insertions(+), 3 deletions(-) diff --git a/arch/alpha/include/uapi/asm/siginfo.h b/arch/alpha/include/uapi/asm/siginfo.h index 9822362a8424..972f547d9e41 100644 --- a/arch/alpha/include/uapi/asm/siginfo.h +++ b/arch/alpha/include/uapi/asm/siginfo.h @@ -6,4 +6,18 @@ #include +/* + * SIGFPE si_codes + */ +#ifdef __KERNEL__ +#define FPE_FIXME (__SI_FAULT|0) /* Broken dup of SI_USER */ +#endif /* __KERNEL__ */ + +/* + * SIGTRAP si_codes + */ +#ifdef __KERNEL__ +#define TRAP_FIXME (__SI_FAULT|0) /* Broken dup of SI_USER */ +#endif /* __KERNEL__ */ + #endif diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c index 65bb102d985b..e94f4b73ac04 100644 --- a/arch/alpha/kernel/traps.c +++ b/arch/alpha/kernel/traps.c @@ -278,7 +278,7 @@ do_entIF(unsigned long type, struct pt_regs *regs) case 1: /* bugcheck */ info.si_signo = SIGTRAP; info.si_errno = 0; - info.si_code = __SI_FAULT; + info.si_code = TRAP_FIXME; info.si_addr = (void __user *) regs->pc; info.si_trapno = 0; send_sig_info(SIGTRAP, &info, current); @@ -318,7 +318,7 @@ do_entIF(unsigned long type, struct pt_regs *regs) break; case GEN_ROPRAND: signo = SIGFPE; - code = __SI_FAULT; + code = FPE_FIXME; break; case GEN_DECOVF: @@ -340,7 +340,7 @@ do_entIF(unsigned long type, struct pt_regs *regs) case GEN_SUBRNG7: default: signo = SIGTRAP; - code = __SI_FAULT; + code = TRAP_FIXME; break; } -- 2.10.1