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From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Lai Jiangshan <laijs@linux.alibaba.com>,
	Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>
Subject: [PATCH V2 18/41] x86/entry: Call paranoid_exit() in asm_exc_nmi()
Date: Sun, 26 Sep 2021 23:08:15 +0800	[thread overview]
Message-ID: <20210926150838.197719-19-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20210926150838.197719-1-jiangshanlai@gmail.com>

From: Lai Jiangshan <laijs@linux.alibaba.com>

The code between "call exc_nmi" and nmi_restore is as the same as
paranoid_exit(), so we can just use paranoid_exit() instead of the open
duplicated code.

No functional change intended.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
 arch/x86/entry/entry_64.S | 34 +++++-----------------------------
 1 file changed, 5 insertions(+), 29 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 202253c9a4f2..a0d73dc0d2f3 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -922,8 +922,7 @@ SYM_CODE_END(paranoid_entry)
 
 /*
  * "Paranoid" exit path from exception stack.  This is invoked
- * only on return from non-NMI IST interrupts that came
- * from kernel space.
+ * only on return from IST interrupts that came from kernel space.
  *
  * We may be returning to very strange contexts (e.g. very early
  * in syscall entry), so checking for preemption here would
@@ -1271,11 +1270,7 @@ end_repeat_nmi:
 	pushq	$-1				/* ORIG_RAX: no syscall to restart */
 
 	/*
-	 * Use paranoid_entry to handle SWAPGS, but no need to use paranoid_exit
-	 * as we should not be calling schedule in NMI context.
-	 * Even with normal interrupts enabled. An NMI should not be
-	 * setting NEED_RESCHED or anything that normal interrupts and
-	 * exceptions might do.
+	 * Use paranoid_entry to handle SWAPGS and CR3.
 	 */
 	call	paranoid_entry
 	UNWIND_HINT_REGS
@@ -1284,31 +1279,12 @@ end_repeat_nmi:
 	movq	$-1, %rsi
 	call	exc_nmi
 
-	/* Always restore stashed CR3 value (see paranoid_entry) */
-	RESTORE_CR3 scratch_reg=%r15 save_reg=%r14
-
 	/*
-	 * The above invocation of paranoid_entry stored the GSBASE
-	 * related information in R/EBX depending on the availability
-	 * of FSGSBASE.
-	 *
-	 * If FSGSBASE is enabled, restore the saved GSBASE value
-	 * unconditionally, otherwise take the conditional SWAPGS path.
+	 * Use paranoid_exit to handle SWAPGS and CR3, but no need to use
+	 * restore_regs_and_return_to_kernel as we must handle nested NMI.
 	 */
-	ALTERNATIVE "jmp nmi_no_fsgsbase", "", X86_FEATURE_FSGSBASE
-
-	wrgsbase	%rbx
-	jmp	nmi_restore
-
-nmi_no_fsgsbase:
-	/* EBX == 0 -> invoke SWAPGS */
-	testl	%ebx, %ebx
-	jnz	nmi_restore
-
-nmi_swapgs:
-	swapgs
+	call	paranoid_exit
 
-nmi_restore:
 	POP_REGS
 
 	/*
-- 
2.19.1.6.gb485710b


  parent reply	other threads:[~2021-09-26 15:11 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-26 15:07 [PATCH V2 00/41] x86/entry/64: Convert a bunch of ASM entry code into C code Lai Jiangshan
2021-09-26 15:07 ` [PATCH V2 01/41] x86/entry: Fix swapgs fence Lai Jiangshan
2021-09-26 20:43   ` Thomas Gleixner
2021-09-27  1:10     ` Lai Jiangshan
2021-09-27  3:27       ` Lai Jiangshan
2021-09-27  7:50         ` Thomas Gleixner
2021-09-26 15:07 ` [PATCH V2 02/41] x86/traps: Remove stack-protector from traps.c Lai Jiangshan
2021-09-27 10:19   ` Borislav Petkov
2021-09-27 10:49     ` Lai Jiangshan
2021-09-27 11:01       ` Borislav Petkov
2021-09-27 14:38         ` Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 03/41] compiler_types.h: Add __noinstr_section() for noinstr Lai Jiangshan
2021-09-27 18:09   ` Kees Cook
2021-09-26 15:08 ` [PATCH V2 04/41] x86/entry: Introduce __entry_text for entry code written in C Lai Jiangshan
2021-09-30 11:49   ` Borislav Petkov
2021-09-26 15:08 ` [PATCH V2 05/41] x86/entry: Move PTI_USER_* to arch/x86/include/asm/processor-flags.h Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 06/41] x86: Mark __native_read_cr3() & native_write_cr3() as __always_inline Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 07/41] x86/traps: Move the declaration of native_irq_return_iret into proto.h Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 08/41] x86/entry: Add arch/x86/entry/entry64.c for C entry code Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 09/41] x86/entry: Expose the address of .Lgs_change to entry64.c Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 10/41] x86/entry: Add C verion of SWITCH_TO_KERNEL_CR3 as switch_to_kernel_cr3() Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 11/41] x86/entry: Add C user_entry_swapgs_and_fence() and kernel_entry_fence_no_swapgs() Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 12/41] x86/traps: Move pt_regs only in fixup_bad_iret() Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 13/41] x86/entry: Switch the stack after error_entry() returns Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 14/41] x86/entry: move PUSH_AND_CLEAR_REGS out of error_entry Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 15/41] objtool: Allow .entry.text function using CLD instruction Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 16/41] x86/entry: Implement the whole error_entry() as C code Lai Jiangshan
2021-09-28 21:34   ` Brian Gerst
2021-09-29  8:45     ` Peter Zijlstra
2021-09-26 15:08 ` [PATCH V2 17/41] x86/entry: Make paranoid_exit() callable Lai Jiangshan
2021-09-26 15:08 ` Lai Jiangshan [this message]
2021-09-26 15:08 ` [PATCH V2 19/41] x86/entry: move PUSH_AND_CLEAR_REGS out of paranoid_entry Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 20/41] x86/entry: Add the C version ist_switch_to_kernel_cr3() Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 21/41] x86/entry: Add the C version ist_restore_cr3() Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 22/41] x86/entry: Add the C version get_percpu_base() Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 23/41] x86/entry: Add the C version ist_switch_to_kernel_gsbase() Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 24/41] x86/entry: Implement the C version ist_paranoid_entry() Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 25/41] x86/entry: Implement the C version ist_paranoid_exit() Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 26/41] x86/entry: Add a C macro to define the function body for IST in .entry.text Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 27/41] x86/mce: Remove stack protector from mce/core.c Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 28/41] x86/debug, mce: Use C entry code Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 29/41] x86/idtentry.h: Move the definitions *IDTENTRY_{MCE|DEBUG}* up Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 30/41] x86/nmi: Use DEFINE_IDTENTRY_NMI for nmi Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 31/41] x86/nmi: Remove stack protector from nmi.c Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 32/41] x86/nmi: Use C entry code Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 33/41] x86/entry: Add a C macro to define the function body for IST in .entry.text with an error code Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 34/41] x86/doublefault: Use C entry code Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 35/41] x86/sev: Add and use ist_vc_switch_off_ist() Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 36/41] x86/sev: Remove stack protector from sev.c Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 37/41] x86/sev: Use C entry code Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 38/41] x86/entry: Remove ASM function paranoid_entry() and paranoid_exit() Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 39/41] x86/entry: Remove the unused ASM macros Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 40/41] x86/entry: Remove save_ret from PUSH_AND_CLEAR_REGS Lai Jiangshan
2021-09-26 15:08 ` [PATCH V2 41/41] x86/syscall/64: Move the checking for sysret to C code Lai Jiangshan

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