linux-kernel - [tip:x86/asm] x86/entry/64: Remove the restore_c_regs_and

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Date:   Thu, 2 Nov 2017 03:49:01 -0700
From:   tip-bot for Andy Lutomirski <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     luto@...nel.org, hpa@...or.com, mingo@...nel.org,
        linux-kernel@...r.kernel.org, dave.hansen@...el.com,
        peterz@...radead.org, tglx@...utronix.de, bpetkov@...e.de,
        bp@...e.de, torvalds@...ux-foundation.org, brgerst@...il.com
Subject: [tip:x86/asm] x86/entry/64: Remove the restore_c_regs_and_iret
 label

Commit-ID:  9da78ba6b47b46428cfdfc0851511ab29c869798
Gitweb:     https://git.kernel.org/tip/9da78ba6b47b46428cfdfc0851511ab29c869798
Author:     Andy Lutomirski <luto@...nel.org>
AuthorDate: Thu, 2 Nov 2017 00:58:58 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 2 Nov 2017 11:04:36 +0100

x86/entry/64: Remove the restore_c_regs_and_iret label

The only user was the 64-bit opportunistic SYSRET failure path, and
that path didn't really need it.  This change makes the
opportunistic SYSRET code a bit more straightforward and gets rid of
the label.

Signed-off-by: Andy Lutomirski <luto@...nel.org>
Reviewed-by: Borislav Petkov <bp@...e.de>
Cc: Borislav Petkov <bpetkov@...e.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/be3006a7ad3326e3458cf1cc55d416252cbe1986.1509609304.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/entry/entry_64.S | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 846e84a..e8ef83d 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -245,7 +245,6 @@ entry_SYSCALL64_slow_path:
 	call	do_syscall_64		/* returns with IRQs disabled */
 
 return_from_SYSCALL_64:
-	RESTORE_EXTRA_REGS
 	TRACE_IRQS_IRETQ		/* we're about to change IF */
 
 	/*
@@ -314,6 +313,7 @@ return_from_SYSCALL_64:
 	 */
 syscall_return_via_sysret:
 	/* rcx and r11 are already restored (see code above) */
+	RESTORE_EXTRA_REGS
 	RESTORE_C_REGS_EXCEPT_RCX_R11
 	movq	RSP(%rsp), %rsp
 	UNWIND_HINT_EMPTY
@@ -321,7 +321,7 @@ syscall_return_via_sysret:
 
 opportunistic_sysret_failed:
 	SWAPGS
-	jmp	restore_c_regs_and_iret
+	jmp	restore_regs_and_iret
 END(entry_SYSCALL_64)
 
 ENTRY(stub_ptregs_64)
@@ -638,7 +638,6 @@ retint_kernel:
  */
 GLOBAL(restore_regs_and_iret)
 	RESTORE_EXTRA_REGS
-restore_c_regs_and_iret:
 	RESTORE_C_REGS
 	REMOVE_PT_GPREGS_FROM_STACK 8
 	INTERRUPT_RETURN