From be756593e543b901edc0e7489949f08c8d2737bf Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Sun, 28 Jan 2018 10:38:50 -0800 Subject: [PATCH 23/42] x86/asm: Move 'status' from thread_struct to thread_info (cherry picked from commit 37a8f7c38339b22b69876d6f5a0ab851565284e3) The TS_COMPAT bit is very hot and is accessed from code paths that mostly also touch thread_info::flags. Move it into struct thread_info to improve cache locality. The only reason it was in thread_struct is that there was a brief period during which arch-specific fields were not allowed in struct thread_info. Linus suggested further changing: ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED); to: if (unlikely(ti->status & (TS_COMPAT|TS_I386_REGS_POKED))) ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED); on the theory that frequently dirtying the cacheline even in pure 64-bit code that never needs to modify status hurts performance. That could be a reasonable followup patch, but I suspect it matters less on top of this patch. Suggested-by: Linus Torvalds Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Reviewed-by: Ingo Molnar Acked-by: Linus Torvalds Cc: Borislav Petkov Cc: Kernel Hardening Link: https://lkml.kernel.org/r/03148bcc1b217100e6e8ecf6a5468c45cf4304b6.1517164461.git.luto@kernel.org Signed-off-by: David Woodhouse Signed-off-by: Greg Kroah-Hartman --- arch/x86/entry/common.c | 4 ++-- arch/x86/include/asm/processor.h | 2 -- arch/x86/include/asm/syscall.h | 6 +++--- arch/x86/include/asm/thread_info.h | 3 ++- arch/x86/kernel/process_64.c | 4 ++-- arch/x86/kernel/ptrace.c | 2 +- arch/x86/kernel/signal.c | 2 +- 7 files changed, 11 insertions(+), 12 deletions(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index bdd9cc5..bd1d102 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -201,7 +201,7 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs) * special case only applies after poking regs and before the * very next return to user mode. */ - current->thread.status &= ~(TS_COMPAT|TS_I386_REGS_POKED); + ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED); #endif user_enter_irqoff(); @@ -299,7 +299,7 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs) unsigned int nr = (unsigned int)regs->orig_ax; #ifdef CONFIG_IA32_EMULATION - current->thread.status |= TS_COMPAT; + ti->status |= TS_COMPAT; #endif if (READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY) { diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index e40b19c..a781668 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -391,8 +391,6 @@ struct thread_struct { unsigned short gsindex; #endif - u32 status; /* thread synchronous flags */ - #ifdef CONFIG_X86_64 unsigned long fsbase; unsigned long gsbase; diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h index e3c95e8..03eedc2 100644 --- a/arch/x86/include/asm/syscall.h +++ b/arch/x86/include/asm/syscall.h @@ -60,7 +60,7 @@ static inline long syscall_get_error(struct task_struct *task, * TS_COMPAT is set for 32-bit syscall entries and then * remains set until we return to user mode. */ - if (task->thread.status & (TS_COMPAT|TS_I386_REGS_POKED)) + if (task->thread_info.status & (TS_COMPAT|TS_I386_REGS_POKED)) /* * Sign-extend the value so (int)-EFOO becomes (long)-EFOO * and will match correctly in comparisons. @@ -116,7 +116,7 @@ static inline void syscall_get_arguments(struct task_struct *task, unsigned long *args) { # ifdef CONFIG_IA32_EMULATION - if (task->thread.status & TS_COMPAT) + if (task->thread_info.status & TS_COMPAT) switch (i) { case 0: if (!n--) break; @@ -177,7 +177,7 @@ static inline void syscall_set_arguments(struct task_struct *task, const unsigned long *args) { # ifdef CONFIG_IA32_EMULATION - if (task->thread.status & TS_COMPAT) + if (task->thread_info.status & TS_COMPAT) switch (i) { case 0: if (!n--) break; diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index bdf9c4c..89978b9 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -54,6 +54,7 @@ struct task_struct; struct thread_info { unsigned long flags; /* low level flags */ + u32 status; /* thread synchronous flags */ }; #define INIT_THREAD_INFO(tsk) \ @@ -213,7 +214,7 @@ static inline int arch_within_stack_frames(const void * const stack, #define in_ia32_syscall() true #else #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \ - current->thread.status & TS_COMPAT) + current_thread_info()->status & TS_COMPAT) #endif /* diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index b3760b3..dca15e1 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -512,7 +512,7 @@ void set_personality_ia32(bool x32) current->personality &= ~READ_IMPLIES_EXEC; /* in_compat_syscall() uses the presence of the x32 syscall bit flag to determine compat status */ - current->thread.status &= ~TS_COMPAT; + current_thread_info()->status &= ~TS_COMPAT; } else { set_thread_flag(TIF_IA32); clear_thread_flag(TIF_X32); @@ -520,7 +520,7 @@ void set_personality_ia32(bool x32) current->mm->context.ia32_compat = TIF_IA32; current->personality |= force_personality32; /* Prepare the first "return" to user space */ - current->thread.status |= TS_COMPAT; + current_thread_info()->status |= TS_COMPAT; } } EXPORT_SYMBOL_GPL(set_personality_ia32); diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 0e63c02..e497d37 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -934,7 +934,7 @@ static int putreg32(struct task_struct *child, unsigned regno, u32 value) */ regs->orig_ax = value; if (syscall_get_nr(child, regs) >= 0) - child->thread.status |= TS_I386_REGS_POKED; + child->thread_info.status |= TS_I386_REGS_POKED; break; case offsetof(struct user32, regs.eflags): diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 763af1d..b1a5d25 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -785,7 +785,7 @@ static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) * than the tracee. */ #ifdef CONFIG_IA32_EMULATION - if (current->thread.status & (TS_COMPAT|TS_I386_REGS_POKED)) + if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED)) return __NR_ia32_restart_syscall; #endif #ifdef CONFIG_X86_X32_ABI -- 2.7.4