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Message-Id: <1457369527-11452-2-git-send-email-stsp@list.ru>
Date: Mon, 7 Mar 2016 19:52:04 +0300
From: Stas Sergeev <stsp@...t.ru>
To: stsp@...t.ru
Cc: linux-kernel@...r.kernel.org,
Andy Lutomirski <luto@...capital.net>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
Borislav Petkov <bp@...e.de>, Brian Gerst <brgerst@...il.com>,
Oleg Nesterov <oleg@...hat.com>,
Richard Weinberger <richard@....at>,
Stas Sergeev <stsp@...rs.sourceforge.net>
Subject: [PATCH 1/4] [Cleanup] x86: signal: unify the sigaltstack check with other arches
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 arches.
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 have no any user-visible impact. It is purely a cleanup.
CC: linux-kernel@...r.kernel.org
CC: Andy Lutomirski <luto@...capital.net>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: Ingo Molnar <mingo@...hat.com>
CC: "H. Peter Anvin" <hpa@...or.com>
CC: x86@...nel.org
CC: Borislav Petkov <bp@...e.de>
CC: Brian Gerst <brgerst@...il.com>
CC: Oleg Nesterov <oleg@...hat.com>
CC: Richard Weinberger <richard@....at>
Signed-off-by: Stas Sergeev <stsp@...rs.sourceforge.net>
---
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 cb6282c..285183b 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -213,18 +213,17 @@ 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) {
--
2.7.2
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