Messages in this thread Patch in this message | | | From | Stas Sergeev <> | Subject | [PATCH 1/4] [Cleanup] x86: signal: unify the sigaltstack check with other arches | Date | Mon, 7 Mar 2016 19:39:41 +0300 |
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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 <luto@amacapital.net> CC: Thomas Gleixner <tglx@linutronix.de> CC: Ingo Molnar <mingo@redhat.com> CC: "H. Peter Anvin" <hpa@zytor.com> CC: x86@kernel.org CC: Borislav Petkov <bp@suse.de> CC: Brian Gerst <brgerst@gmail.com> CC: Oleg Nesterov <oleg@redhat.com> CC: Richard Weinberger <richard@nod.at>
Signed-off-by: Stas Sergeev <stsp@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
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