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From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: x86@kernel.org, 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>,
	"H. Peter Anvin" <hpa@zytor.com>
Subject: [PATCH V3 22/49] x86/entry: Don't call error_entry for XENPV
Date: Thu, 14 Oct 2021 11:33:45 +0800	[thread overview]
Message-ID: <20211014033414.16321-17-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20211014031413.14471-1-jiangshanlai@gmail.com>

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

When in XENPV, it is already in the task stack, and it can't fault
at native_irq_return_iret nor asm_load_gs_index_gs_change since
XENPV uses its own pvops for iret and load_gs_index().  And it
doesn't need to switch CR3.  So it can skip invoking error_entry().

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
 arch/x86/entry/entry_64.S | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 52a08c4a0171..9bad620553c8 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -326,8 +326,17 @@ SYM_CODE_END(ret_from_fork)
 	PUSH_AND_CLEAR_REGS
 	ENCODE_FRAME_POINTER
 
-	call	error_entry
-	movq	%rax, %rsp			/* switch stack settled by sync_regs() */
+	/*
+	 * Call error_entry and switch stack settled by sync_regs().
+	 *
+	 * When in XENPV, it is already in the task stack, and it can't fault
+	 * at native_irq_return_iret nor asm_load_gs_index_gs_change since
+	 * XENPV uses its own pvops for iret and load_gs_index().  And it
+	 * doesn't need to switch CR3.  So it can skip invoking error_entry().
+	 */
+	ALTERNATIVE "call error_entry; movq %rax, %rsp", \
+		"", X86_FEATURE_XENPV
+
 	ENCODE_FRAME_POINTER
 	UNWIND_HINT_REGS
 
-- 
2.19.1.6.gb485710b


  parent reply	other threads:[~2021-10-14  3:36 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-14  3:13 [PATCH V3 00/49] x86/entry/64: Convert a bunch of ASM entry code into C code Lai Jiangshan
2021-10-14  3:13 ` [PATCH V3 01/49] x86/entry: Add fence for kernel entry swapgs in paranoid_entry() Lai Jiangshan
2021-10-14  3:13 ` [PATCH V3 02/49] x86/entry: Use the correct fence macro after swapgs in kernel CR3 Lai Jiangshan
2021-10-14  3:13 ` [PATCH V3 03/49] x86/traps: Remove stack-protector from traps.c Lai Jiangshan
2021-10-14  3:13 ` [PATCH V3 04/49] x86/xen: Add xenpv_restore_regs_and_return_to_usermode() Lai Jiangshan
2021-10-16 18:08   ` Boris Ostrovsky
2021-10-14  3:13 ` [PATCH V3 05/49] x86/entry: Use swapgs and native_iret directly in swapgs_restore_regs_and_return_to_usermode Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 06/49] compiler_types.h: Add __noinstr_section() for noinstr Lai Jiangshan
2021-10-14 18:29   ` Nick Desaulniers
2021-10-14 18:35     ` Miguel Ojeda
2021-10-18  9:16       ` Lai Jiangshan
2021-10-18 11:29         ` Miguel Ojeda
2021-10-14  3:33 ` [PATCH V3 07/49] x86/entry: Introduce __entry_text for entry code written in C Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 08/49] x86/entry: Move PTI_USER_* to arch/x86/include/asm/processor-flags.h Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 09/49] x86: Remove unused kernel_to_user_p4dp() and user_to_kernel_p4dp() Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 10/49] x86: Replace PTI_PGTABLE_SWITCH_BIT with PTI_USER_PGTABLE_BIT Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 11/49] x86: Mark __native_read_cr3() & native_write_cr3() as __always_inline Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 12/49] x86/traps: Move the declaration of native_irq_return_iret into proto.h Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 13/49] x86/entry: Add arch/x86/entry/entry64.c for C entry code Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 14/49] x86/entry: Expose the address of .Lgs_change to entry64.c Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 15/49] x86/entry: Add C verion of SWITCH_TO_KERNEL_CR3 as switch_to_kernel_cr3() Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 16/49] x86/traps: Add fence_swapgs_{user,kernel}_entry() Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 17/49] x86/entry: Add C {user,kernel}_entry_swapgs_and_fence() Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 18/49] x86/traps: Move pt_regs only in fixup_bad_iret() Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 19/49] x86/entry: Switch the stack after error_entry() returns Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 20/49] x86/entry: move PUSH_AND_CLEAR_REGS out of error_entry Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 21/49] x86/entry: Move cld to the start of idtentry Lai Jiangshan
2021-10-14  3:33 ` Lai Jiangshan [this message]
2021-10-14  3:33 ` [PATCH V3 23/49] x86/entry: Convert SWAPGS to swapgs in error_entry() Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 24/49] x86/entry: Implement the whole error_entry() as C code Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 25/49] x86/entry: Use idtentry macro for entry_INT80_compat Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 26/49] x86/entry: Convert SWAPGS to swapgs in entry_SYSENTER_compat() Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 27/49] x86: Remove the definition of SWAPGS Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 28/49] x86/entry: Make paranoid_exit() callable Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 29/49] x86/entry: Call paranoid_exit() in asm_exc_nmi() Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 30/49] x86/entry: move PUSH_AND_CLEAR_REGS out of paranoid_entry Lai Jiangshan
2021-10-14  3:33 ` [PATCH V3 31/49] x86/entry: Add the C version ist_switch_to_kernel_cr3() Lai Jiangshan
2021-10-14  3:41 ` [PATCH V3 32/49] x86/entry: Add the C version ist_restore_cr3() Lai Jiangshan
2021-10-25  0:34   ` Lai Jiangshan
2021-10-14  3:41 ` [PATCH V3 33/49] x86/entry: Add the C version get_percpu_base() Lai Jiangshan
2021-10-14  3:41 ` [PATCH V3 34/49] x86/entry: Add the C version ist_switch_to_kernel_gsbase() Lai Jiangshan
2021-10-14  3:41 ` [PATCH V3 35/49] x86/entry: Implement the C version ist_paranoid_entry() Lai Jiangshan
2021-10-14  3:50 ` [PATCH V3 36/49] x86/entry: Implement the C version ist_paranoid_exit() Lai Jiangshan
2021-10-14  3:50 ` [PATCH V3 37/49] x86/entry: Add a C macro to define the function body for IST in .entry.text Lai Jiangshan
2021-10-14  3:50 ` [PATCH V3 38/49] x86/debug, mce: Use C entry code Lai Jiangshan
2021-10-14  3:50 ` [PATCH V3 39/49] x86/idtentry.h: Move the definitions *IDTENTRY_{MCE|DEBUG}* up Lai Jiangshan
2021-10-14  3:50 ` [PATCH V3 40/49] x86/nmi: Use DEFINE_IDTENTRY_NMI for nmi Lai Jiangshan
2021-10-14  3:50 ` [PATCH V3 41/49] x86/nmi: Use C entry code Lai Jiangshan
2021-10-14  3:50 ` [PATCH V3 42/49] x86/entry: Add a C macro to define the function body for IST in .entry.text with an error code Lai Jiangshan
2021-10-14  3:58 ` [PATCH V3 43/49] x86/doublefault: Use C entry code Lai Jiangshan
2021-10-14  3:58 ` [PATCH V3 44/49] x86/sev: Add and use ist_vc_switch_off_ist() Lai Jiangshan
2021-10-14  3:58 ` [PATCH V3 45/49] x86/sev: Use C entry code Lai Jiangshan
2021-10-14  3:58 ` [PATCH V3 46/49] x86/entry: Remove ASM function paranoid_entry() and paranoid_exit() Lai Jiangshan
2021-10-14  3:58 ` [PATCH V3 47/49] x86/entry: Remove the unused ASM macros Lai Jiangshan
2021-10-14  3:58 ` [PATCH V3 48/49] x86/entry: Remove save_ret from PUSH_AND_CLEAR_REGS Lai Jiangshan
2021-10-14  3:58 ` [PATCH V3 49/49] x86/syscall/64: Move the checking for sysret to C code Lai Jiangshan
2021-10-23  0:01 ` [PATCH V3 00/49] x86/entry/64: Convert a bunch of ASM entry code into " Lai Jiangshan

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