[RFC PATCH for 4.18 1/2] compat: Introduce is_compat_frame
STALE3020d
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: 2018-06-26 21:16:41
Also in:
linux-arch, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
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 <mathieu.desnoyers@efficios.com> Cc: Thomas Gleixner <redacted> Cc: Joel Fernandes <redacted> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Watson <redacted> Cc: Will Deacon <redacted> Cc: Andi Kleen <redacted> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: Chris Lameter <redacted> Cc: Russell King <redacted> Cc: Andrew Hunter <redacted> Cc: Michael Kerrisk <redacted> Cc: "Paul E . McKenney" <redacted> Cc: Paul Turner <redacted> Cc: Boqun Feng <redacted> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ben Maurer <redacted> Cc: linux-api@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: x86@kernel.org Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> --- 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 <linux/types.h> #include <linux/sched.h> #include <linux/sched/task_stack.h> +#include <linux/signal.h> #include <asm/processor.h> #include <asm/user32.h> #include <asm/unistd.h>
@@ -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