From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mathieu Desnoyers Subject: [RFC PATCH for 4.18 1/2] compat: Introduce is_compat_frame Date: Tue, 26 Jun 2018 17:16:16 -0400 Message-ID: <20180626211617.8933-1-mathieu.desnoyers@efficios.com> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Andy Lutomirski , Thomas Gleixner Cc: linux-kernel@vger.kernel.org, Mathieu Desnoyers , Joel Fernandes , Peter Zijlstra , Catalin Marinas , Dave Watson , Will Deacon , Andi Kleen , "H . Peter Anvin" , Chris Lameter , Russell King , Andrew Hunter , Michael Kerrisk , "Paul E . McKenney" , Paul Turner , Boqun Feng , Josh Triplett , Steven Rostedt , Ben Maurer , linux-api@vger.kernel.org, linux-arch@vger.kernel. List-Id: linux-api@vger.kernel.org x86 is moving from is_compat_task() to in_compat_syscall(). However, in_compat_syscall cannot be used to check whether a signal is being delivered on a compat task. Introduce is_compat_frame to allow performing this check from architecture agnostic code. On all architectures except x86, it invokes is_compat_task(). On x86, it uses is_ia32_frame() and is_x32_frame() to check whether the signal frame is 32-bit. This is needed by restartable sequences to detect whether it needs to clear the top bits of the start_ip, abort_ip, and post_commit_offset rseq_cs fields on signal delivery, thus ensuring identical behavior for a 32-bit binary executed on 32-bit and 64-bit kernels. Signed-off-by: Mathieu Desnoyers Cc: Thomas Gleixner Cc: Joel Fernandes Cc: Peter Zijlstra Cc: Catalin Marinas Cc: Dave Watson Cc: Will Deacon Cc: Andi Kleen Cc: "H . Peter Anvin" Cc: Chris Lameter Cc: Russell King Cc: Andrew Hunter Cc: Michael Kerrisk Cc: "Paul E . McKenney" Cc: Paul Turner Cc: Boqun Feng Cc: Josh Triplett Cc: Steven Rostedt Cc: Ben Maurer Cc: linux-api@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: x86@kernel.org Cc: Andy Lutomirski Cc: Andrew Morton Cc: Linus Torvalds --- arch/x86/include/asm/compat.h | 24 ++++++++++++++++++++++++ arch/x86/kernel/signal.c | 17 ----------------- include/linux/compat.h | 17 +++++++++++++++++ 3 files changed, 41 insertions(+), 17 deletions(-) diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h index fb97cf7c4137..1405a8df5215 100644 --- a/arch/x86/include/asm/compat.h +++ b/arch/x86/include/asm/compat.h @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -242,4 +243,27 @@ struct compat_siginfo; int __copy_siginfo_to_user32(struct compat_siginfo __user *to, const siginfo_t *from, bool x32_ABI); +static inline int is_ia32_compat_frame(struct ksignal *ksig) +{ + return IS_ENABLED(CONFIG_IA32_EMULATION) && + ksig->ka.sa.sa_flags & SA_IA32_ABI; +} + +static inline int is_ia32_frame(struct ksignal *ksig) +{ + return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig); +} + +static inline int is_x32_frame(struct ksignal *ksig) +{ + return IS_ENABLED(CONFIG_X86_X32_ABI) && + ksig->ka.sa.sa_flags & SA_X32_ABI; +} + +static inline bool is_compat_frame(struct ksignal *ksig) +{ + return is_ia32_frame(ksig) || is_x32_frame(ksig); +} +#define is_compat_frame is_compat_frame /* override the generic impl */ + #endif /* _ASM_X86_COMPAT_H */ diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 92a3b312a53c..cb488e3e952d 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -664,23 +664,6 @@ SYSCALL_DEFINE0(rt_sigreturn) return 0; } -static inline int is_ia32_compat_frame(struct ksignal *ksig) -{ - return IS_ENABLED(CONFIG_IA32_EMULATION) && - ksig->ka.sa.sa_flags & SA_IA32_ABI; -} - -static inline int is_ia32_frame(struct ksignal *ksig) -{ - return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig); -} - -static inline int is_x32_frame(struct ksignal *ksig) -{ - return IS_ENABLED(CONFIG_X86_X32_ABI) && - ksig->ka.sa.sa_flags & SA_X32_ABI; -} - static int setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) { diff --git a/include/linux/compat.h b/include/linux/compat.h index b1a5562b3215..2e1ffba65117 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -1022,6 +1022,19 @@ static inline struct compat_timeval ns_to_compat_timeval(s64 nsec) return ctv; } +/* + * For most but not all architectures, "is this a compat sigframe?" and + * "am I a compat task?" are the same question. For architectures on which + * they aren't the same question, arch code can override is_compat_frame. + */ + +#ifndef is_compat_frame +static inline bool is_compat_frame(struct ksignal *ksig) +{ + return is_compat_task(); +} +#endif + #else /* !CONFIG_COMPAT */ #define is_compat_task() (0) @@ -1029,6 +1042,10 @@ static inline struct compat_timeval ns_to_compat_timeval(s64 nsec) static inline bool in_compat_syscall(void) { return false; } #endif +#ifndef is_compat_frame +static inline bool is_compat_frame(struct ksignal *ksig) { return false; } +#endif + #endif /* CONFIG_COMPAT */ #endif /* _LINUX_COMPAT_H */ -- 2.11.0