From 0b4521e8cf1f582da3045ea460427ac2f741578f Mon Sep 17 00:00:00 2001 From: Stas Sergeev Date: Thu, 14 Apr 2016 23:20:02 +0300 Subject: [PATCH] signals/sigaltstack, x86/signals: Unify the x86 sigaltstack check with other architectures Currently x86's get_sigframe() checks for "current->sas_ss_size" to determine whether there is a need to switch to sigaltstack. The common practice used by all other arches is to check for sas_ss_flags(sp) == 0 This patch makes the code consistent with other architectures. The slight complexity of the patch is added by the optimization on !sigstack check that was requested by Andy Lutomirski: sas_ss_flags(sp)==0 already implies that we are not on a sigstack, so the code is shuffled to avoid the duplicate checking. This patch should have no user-visible impact. Signed-off-by: Stas Sergeev Cc: Al Viro Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Pavel Emelyanov Cc: Peter Zijlstra Cc: Richard Weinberger Cc: Shuah Khan Cc: Thomas Gleixner Cc: linux-api@vger.kernel.org Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1460665206-13646-2-git-send-email-stsp@list.ru Signed-off-by: Ingo Molnar --- arch/x86/kernel/signal.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 548ddf7d6fd2..3e84ef16f657 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -248,18 +248,17 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, if (config_enabled(CONFIG_X86_64)) sp -= 128; - if (!onsigstack) { - /* This is the X/Open sanctioned signal stack switching. */ - if (ka->sa.sa_flags & SA_ONSTACK) { - if (current->sas_ss_size) - sp = current->sas_ss_sp + current->sas_ss_size; - } else if (config_enabled(CONFIG_X86_32) && - (regs->ss & 0xffff) != __USER_DS && - !(ka->sa.sa_flags & SA_RESTORER) && - ka->sa.sa_restorer) { - /* This is the legacy signal stack switching. */ - sp = (unsigned long) ka->sa.sa_restorer; - } + /* This is the X/Open sanctioned signal stack switching. */ + if (ka->sa.sa_flags & SA_ONSTACK) { + if (sas_ss_flags(sp) == 0) + sp = current->sas_ss_sp + current->sas_ss_size; + } else if (config_enabled(CONFIG_X86_32) && + !onsigstack && + (regs->ss & 0xffff) != __USER_DS && + !(ka->sa.sa_flags & SA_RESTORER) && + ka->sa.sa_restorer) { + /* This is the legacy signal stack switching. */ + sp = (unsigned long) ka->sa.sa_restorer; } if (fpu->fpstate_active) { -- 2.20.1