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Commit 97245d00 authored by Linus Torvalds's avatar Linus Torvalds Committed by Ingo Molnar
Browse files

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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jann Horn <jann@thejh.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/6376aa81c68798cc81631673f52bd91a3e078944.1473801993.git.luto@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent b9d989c7

arch/x86/entry/common.c

+6 −14
Original line number Diff line number Diff line
@@ -31,13 +31,6 @@ 
#define CREATE_TRACE_POINTS

#include <trace/events/syscalls.h>



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