[tip:x86/asm] x86/entry: Get rid of pt_regs_to_thread_info()

[tip-bot for Linus Torvalds]

Commit-ID:  97245d00585d82540f4538cf72d92a1e853c7b0e
Gitweb: http://git.kernel.org/tip/97245d00585d82540f4538cf72d92a1e853c7b0e
Author: Linus Torvalds 
AuthorDate: Tue, 13 Sep 2016 14:29:22 -0700
Committer:  Ingo Molnar 
CommitDate: Thu, 15 Sep 2016 08:25:12 +0200

x86/entry: Get rid of pt_regs_to_thread_info()

It was a nice optimization while it lasted, but thread_info is moving
and this optimization will no longer work.

Quoting Linus:

Oh Gods, Andy. That pt_regs_to_thread_info() thing made me want
to do unspeakable acts on a poor innocent wax figure that looked
_exactly_ like you.

[ Changelog written by Andy. ]
Signed-off-by: Linus Torvalds 
Signed-off-by: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Jann Horn 
Cc: Josh Poimboeuf 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: 
http://lkml.kernel.org/r/6376aa81c68798cc81631673f52bd91a3e078944.1473801993.git.l...@kernel.org
Signed-off-by: Ingo Molnar 
---
 arch/x86/entry/common.c | 20 ++--
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 871bbf9..bdd9cc5 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -31,13 +31,6 @@
 #define CREATE_TRACE_POINTS
 #include 
 
-static struct thread_info *pt_regs_to_thread_info(struct pt_regs *regs)
-{
-   unsigned long top_of_stack =
-   (unsigned long)(regs + 1) + TOP_OF_KERNEL_STACK_PADDING;
-   return (struct thread_info *)(top_of_stack - THREAD_SIZE);
-}
-
 #ifdef CONFIG_CONTEXT_TRACKING
 /* Called on entry from user mode with IRQs off. */
 __visible inline void enter_from_user_mode(void)
@@ -71,7 +64,7 @@ static long syscall_trace_enter(struct pt_regs *regs)
 {
u32 arch = in_ia32_syscall() ? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64;
 
-   struct thread_info *ti = pt_regs_to_thread_info(regs);
+   struct thread_info *ti = current_thread_info();
unsigned long ret = 0;
bool emulated = false;
u32 work;
@@ -173,18 +166,17 @@ static void exit_to_usermode_loop(struct pt_regs *regs, 
u32 cached_flags)
/* Disable IRQs and retry */
local_irq_disable();
 
-   cached_flags = READ_ONCE(pt_regs_to_thread_info(regs)->flags);
+   cached_flags = READ_ONCE(current_thread_info()->flags);
 
if (!(cached_flags & EXIT_TO_USERMODE_LOOP_FLAGS))
break;
-
}
 }
 
 /* Called with IRQs disabled. */
 __visible inline void prepare_exit_to_usermode(struct pt_regs *regs)
 {
-   struct thread_info *ti = pt_regs_to_thread_info(regs);
+   struct thread_info *ti = current_thread_info();
u32 cached_flags;
 
if (IS_ENABLED(CONFIG_PROVE_LOCKING) && WARN_ON(!irqs_disabled()))
@@ -247,7 +239,7 @@ static void syscall_slow_exit_work(struct pt_regs *regs, 
u32 cached_flags)
  */
 __visible inline void syscall_return_slowpath(struct pt_regs *regs)
 {
-   struct thread_info *ti = pt_regs_to_thread_info(regs);
+   struct thread_info *ti = current_thread_info();
u32 cached_flags = READ_ONCE(ti->flags);
 
CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
@@ -270,7 +262,7 @@ __visible inline void syscall_return_slowpath(struct 
pt_regs *regs)
 #ifdef CONFIG_X86_64
 __visible void do_syscall_64(struct pt_regs *regs)
 {
-   struct thread_info *ti = pt_regs_to_thread_info(regs);
+   struct thread_info *ti = current_thread_info();
unsigned long nr = regs->orig_ax;
 
enter_from_user_mode();
@@ -303,7 +295,7 @@ __visible void do_syscall_64(struct pt_regs *regs)
  */
 static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs)
 {
-   struct thread_info *ti = pt_regs_to_thread_info(regs);
+   struct thread_info *ti = current_thread_info();
unsigned int nr = (unsigned int)regs->orig_ax;
 
 #ifdef CONFIG_IA32_EMULATION

[tip:x86/asm] x86/entry: Get rid of pt_regs_to_thread_info()

[tip-bot for Linus Torvalds]

Commit-ID:  97245d00585d82540f4538cf72d92a1e853c7b0e
Gitweb: http://git.kernel.org/tip/97245d00585d82540f4538cf72d92a1e853c7b0e
Author: Linus Torvalds 
AuthorDate: Tue, 13 Sep 2016 14:29:22 -0700
Committer:  Ingo Molnar 
CommitDate: Thu, 15 Sep 2016 08:25:12 +0200

x86/entry: Get rid of pt_regs_to_thread_info()

It was a nice optimization while it lasted, but thread_info is moving
and this optimization will no longer work.

Quoting Linus:

Oh Gods, Andy. That pt_regs_to_thread_info() thing made me want
to do unspeakable acts on a poor innocent wax figure that looked
_exactly_ like you.

[ Changelog written by Andy. ]
Signed-off-by: Linus Torvalds 
Signed-off-by: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Jann Horn 
Cc: Josh Poimboeuf 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: 
http://lkml.kernel.org/r/6376aa81c68798cc81631673f52bd91a3e078944.1473801993.git.l...@kernel.org
Signed-off-by: Ingo Molnar 
---
 arch/x86/entry/common.c | 20 ++--
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 871bbf9..bdd9cc5 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -31,13 +31,6 @@
 #define CREATE_TRACE_POINTS
 #include 
 
-static struct thread_info *pt_regs_to_thread_info(struct pt_regs *regs)
-{
-   unsigned long top_of_stack =
-   (unsigned long)(regs + 1) + TOP_OF_KERNEL_STACK_PADDING;
-   return (struct thread_info *)(top_of_stack - THREAD_SIZE);
-}
-
 #ifdef CONFIG_CONTEXT_TRACKING
 /* Called on entry from user mode with IRQs off. */
 __visible inline void enter_from_user_mode(void)
@@ -71,7 +64,7 @@ static long syscall_trace_enter(struct pt_regs *regs)
 {
u32 arch = in_ia32_syscall() ? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64;
 
-   struct thread_info *ti = pt_regs_to_thread_info(regs);
+   struct thread_info *ti = current_thread_info();
unsigned long ret = 0;
bool emulated = false;
u32 work;
@@ -173,18 +166,17 @@ static void exit_to_usermode_loop(struct pt_regs *regs, 
u32 cached_flags)
/* Disable IRQs and retry */
local_irq_disable();
 
-   cached_flags = READ_ONCE(pt_regs_to_thread_info(regs)->flags);
+   cached_flags = READ_ONCE(current_thread_info()->flags);
 
if (!(cached_flags & EXIT_TO_USERMODE_LOOP_FLAGS))
break;
-
}
 }
 
 /* Called with IRQs disabled. */
 __visible inline void prepare_exit_to_usermode(struct pt_regs *regs)
 {
-   struct thread_info *ti = pt_regs_to_thread_info(regs);
+   struct thread_info *ti = current_thread_info();
u32 cached_flags;
 
if (IS_ENABLED(CONFIG_PROVE_LOCKING) && WARN_ON(!irqs_disabled()))
@@ -247,7 +239,7 @@ static void syscall_slow_exit_work(struct pt_regs *regs, 
u32 cached_flags)
  */
 __visible inline void syscall_return_slowpath(struct pt_regs *regs)
 {
-   struct thread_info *ti = pt_regs_to_thread_info(regs);
+   struct thread_info *ti = current_thread_info();
u32 cached_flags = READ_ONCE(ti->flags);
 
CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
@@ -270,7 +262,7 @@ __visible inline void syscall_return_slowpath(struct 
pt_regs *regs)
 #ifdef CONFIG_X86_64
 __visible void do_syscall_64(struct pt_regs *regs)
 {
-   struct thread_info *ti = pt_regs_to_thread_info(regs);
+   struct thread_info *ti = current_thread_info();
unsigned long nr = regs->orig_ax;
 
enter_from_user_mode();
@@ -303,7 +295,7 @@ __visible void do_syscall_64(struct pt_regs *regs)
  */
 static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs)
 {
-   struct thread_info *ti = pt_regs_to_thread_info(regs);
+   struct thread_info *ti = current_thread_info();
unsigned int nr = (unsigned int)regs->orig_ax;
 
 #ifdef CONFIG_IA32_EMULATION