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@vger.kernel.org
CC: Andy Lutomirski <l...@amacapital.net>
CC: Thomas Gleixner <t...@linutronix.de>
CC: Ingo Molnar <mi...@redhat.com>
CC: "H. Peter Anvin" <h...@zytor.com>
CC: x...@kernel.org
CC: Borislav Petkov <b...@suse.de>
CC: Brian Gerst <brge...@gmail.com>
CC: Oleg Nesterov <o...@redhat.com>
CC: Richard Weinberger <rich...@nod.at>
Signed-off-by: Stas Sergeev <s...@users.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
