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From: Andy Lutomirski <luto@kernel.org>
To: X86 ML <x86@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Brian Gerst <brgerst@gmail.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>
Subject: [PATCH v2 07/20] x86/asm/64: Merge the fast and slow SYSRET paths
Date: Thu,  2 Nov 2017 00:59:04 -0700	[thread overview]
Message-ID: <1204e20233fcab9130a1ba80b3b1879b5db3fc1f.1509609304.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1509609304.git.luto@kernel.org>
In-Reply-To: <cover.1509609304.git.luto@kernel.org>

They did almost the same thing.  Remove a bunch of pointless
instructions (mostly hidden in macros) and reduce cognitive load by
merging them.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/entry/entry_64.S | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 86fdce00e682..2e7f4952af94 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -220,10 +220,9 @@ entry_SYSCALL_64_fastpath:
 	TRACE_IRQS_ON		/* user mode is traced as IRQs on */
 	movq	RIP(%rsp), %rcx
 	movq	EFLAGS(%rsp), %r11
-	RESTORE_C_REGS_EXCEPT_RCX_R11
-	movq	RSP(%rsp), %rsp
+	addq	$6*8, %rsp	/* skip extra regs -- they were preserved */
 	UNWIND_HINT_EMPTY
-	USERGS_SYSRET64
+	jmp	.Lpop_c_regs_except_rcx_r11_and_sysret
 
 1:
 	/*
@@ -317,6 +316,7 @@ syscall_return_via_sysret:
 	/* rcx and r11 are already restored (see code above) */
 	UNWIND_HINT_EMPTY
 	POP_EXTRA_REGS
+.Lpop_c_regs_except_rcx_r11_and_sysret:
 	popq	%rsi	/* skip r11 */
 	popq	%r10
 	popq	%r9
-- 
2.13.6

  parent reply	other threads:[~2017-11-02  8:00 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-02  7:58 [PATCH v2 00/20] Pile o' entry/exit/sp0 changes Andy Lutomirski
2017-11-02  7:58 ` [PATCH v2 01/20] x86/asm/64: Remove the restore_c_regs_and_iret label Andy Lutomirski
2017-11-02 10:49   ` [tip:x86/asm] x86/entry/64: " tip-bot for Andy Lutomirski
2017-11-02  7:58 ` [PATCH v2 02/20] x86/asm/64: Split the iret-to-user and iret-to-kernel paths Andy Lutomirski
2017-11-02 10:49   ` [tip:x86/asm] x86/entry/64: Split the IRET-to-user and IRET-to-kernel paths tip-bot for Andy Lutomirski
2017-11-02 10:50   ` [PATCH v2 02/20] x86/asm/64: Split the iret-to-user and iret-to-kernel paths Borislav Petkov
2017-11-02 12:09     ` [PATCH] x86/entry/64: Shorten TEST instructions Borislav Petkov
2017-11-02 12:48       ` [tip:x86/asm] " tip-bot for Borislav Petkov
2017-11-02  7:59 ` [PATCH v2 03/20] x86/asm/64: Move SWAPGS into the common iret-to-usermode path Andy Lutomirski
2017-11-02 10:49   ` [tip:x86/asm] x86/entry/64: Move SWAPGS into the common IRET-to-usermode path tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 04/20] x86/asm/64: Simplify reg restore code in the standard IRET paths Andy Lutomirski
2017-11-02 10:50   ` [tip:x86/asm] x86/entry/64: " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 05/20] x86/asm/64: Shrink paranoid_exit_restore and make labels local Andy Lutomirski
2017-11-02 10:50   ` [tip:x86/asm] x86/entry/64: " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 06/20] x86/asm/64: Use pop instead of movq in syscall_return_via_sysret Andy Lutomirski
2017-11-02 10:51   ` [tip:x86/asm] x86/entry/64: " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` Andy Lutomirski [this message]
2017-11-02 10:51   ` [tip:x86/asm] x86/entry/64: Merge the fast and slow SYSRET paths tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 08/20] x86/entry/64: Use POP instead of MOV to restore regs on NMI return Andy Lutomirski
2017-11-02 10:51   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 09/20] x86/entry/64: Remove the RESTORE_..._REGS infrastructure Andy Lutomirski
2017-11-02 10:52   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 10/20] xen: add xen nmi trap entry Andy Lutomirski
2017-11-02 10:52   ` [tip:x86/asm] xen, x86/entry/64: Add xen NMI " tip-bot for Juergen Gross
2017-11-02  7:59 ` [PATCH v2 11/20] x86/asm/64: De-Xen-ify our NMI code Andy Lutomirski
2017-11-02 10:53   ` [tip:x86/asm] x86/entry/64: " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 12/20] x86/asm/32: Pull MSR_IA32_SYSENTER_CS update code out of native_load_sp0() Andy Lutomirski
2017-11-02 10:53   ` [tip:x86/asm] x86/entry/32: Pull the " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 13/20] x86/asm/64: Pass sp0 directly to load_sp0() Andy Lutomirski
2017-11-02  9:48   ` Ingo Molnar
2017-11-02  9:53     ` Ingo Molnar
2017-11-02 10:32     ` Andy Lutomirski
2017-11-02 10:53   ` [tip:x86/asm] x86/entry/64: Pass SP0 " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 14/20] x86/asm: Add task_top_of_stack() to find the top of a task's stack Andy Lutomirski
2017-11-02 10:54   ` [tip:x86/asm] x86/entry: " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 15/20] x86/xen/64: Clean up SP code in cpu_initialize_context() Andy Lutomirski
2017-11-02  9:56   ` Juergen Gross
2017-11-02 10:54   ` [tip:x86/asm] x86/xen/64, x86/entry/64: " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 16/20] x86/boot/64: Stop initializing TSS.sp0 at boot Andy Lutomirski
2017-11-02 10:55   ` [tip:x86/asm] x86/entry/64: " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 17/20] x86/asm/64: Remove all remaining direct thread_struct::sp0 reads Andy Lutomirski
2017-11-02 10:55   ` [tip:x86/asm] x86/entry/64: " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 18/20] x86/boot/32: Fix cpu_current_top_of_stack initialization at boot Andy Lutomirski
2017-11-02 10:56   ` [tip:x86/asm] x86/entry/32: " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 19/20] x86/asm/64: Remove thread_struct::sp0 Andy Lutomirski
2017-11-02 10:56   ` [tip:x86/asm] x86/entry/64: " tip-bot for Andy Lutomirski
2017-11-02  7:59 ` [PATCH v2 20/20] x86/traps: Use a new on_thread_stack() helper to clean up an assertion Andy Lutomirski
2017-11-02 10:56   ` [tip:x86/asm] " tip-bot for Andy Lutomirski

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