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From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: x86@kernel.org, Borislav Petkov <bp@alien8.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Lai Jiangshan <jiangshan.ljs@antgroup.com>,
	Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>
Subject: [PATCH V3 4/7] x86/entry: move PUSH_AND_CLEAR_REGS out of error_entry
Date: Tue, 15 Mar 2022 15:39:46 +0800	[thread overview]
Message-ID: <20220315073949.7541-5-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20220315073949.7541-1-jiangshanlai@gmail.com>

From: Lai Jiangshan <jiangshan.ljs@antgroup.com>

Moving PUSH_AND_CLEAR_REGS out of error_entry doesn't change any
functionality.

It makes error_entry() do not fiddle with the stack.

It will enlarge the size:

size arch/x86/entry/entry_64.o.before:
   text	   data	    bss	    dec	    hex	filename
  17916	    384	      0	  18300	   477c	arch/x86/entry/entry_64.o

size --format=SysV arch/x86/entry/entry_64.o.before:
.entry.text                      5528      0
.orc_unwind                      6456      0
.orc_unwind_ip                   4304      0

size arch/x86/entry/entry_64.o.after:
   text	   data	    bss	    dec	    hex	filename
  26868	    384	      0	  27252	   6a74	arch/x86/entry/entry_64.o

size --format=SysV arch/x86/entry/entry_64.o.after:
.entry.text                      8200      0
.orc_unwind                     10224      0
.orc_unwind_ip                   6816      0

But .entry.text in x86_64 is 2M aligned, enlarging it to 8.2k doesn't
enlarge the final text size.

The tables .orc_unwind[_ip] are enlarged due to it adds many pushes.

It is prepared for not calling error_entry() from XENPV in later patch
and for future converting the whole error_entry into C code.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
---
 arch/x86/entry/entry_64.S | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 7768cdd0c7ed..903da9119e7a 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -325,6 +325,9 @@ SYM_CODE_END(ret_from_fork)
  */
 .macro idtentry_body cfunc has_error_code:req
 
+	PUSH_AND_CLEAR_REGS
+	ENCODE_FRAME_POINTER
+
 	call	error_entry
 	movq	%rax, %rsp			/* switch stack settled by sync_regs() */
 	ENCODE_FRAME_POINTER
@@ -1002,8 +1005,6 @@ SYM_CODE_END(paranoid_exit)
 SYM_CODE_START_LOCAL(error_entry)
 	UNWIND_HINT_FUNC
 	cld
-	PUSH_AND_CLEAR_REGS save_ret=1
-	ENCODE_FRAME_POINTER 8
 	testb	$3, CS+8(%rsp)
 	jz	.Lerror_kernelspace
 
-- 
2.19.1.6.gb485710b


  parent reply	other threads:[~2022-03-15  7:39 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-15  7:39 [PATCH V3 0/7] x86/entry: Clean up entry code Lai Jiangshan
2022-03-15  7:39 ` [PATCH V3 1/7] x86/entry: Use idtentry macro for entry_INT80_compat Lai Jiangshan
2022-03-16 13:48   ` Peter Zijlstra
2022-03-15  7:39 ` [PATCH V3 2/7] x86/traps: Move pt_regs only in fixup_bad_iret() Lai Jiangshan
2022-03-15  7:39 ` [PATCH V3 3/7] x86/entry: Switch the stack after error_entry() returns Lai Jiangshan
2022-03-16  2:37   ` Josh Poimboeuf
2022-03-16  3:02     ` Lai Jiangshan
2022-03-16 15:05   ` Peter Zijlstra
2022-03-16 16:43     ` Lai Jiangshan
2022-03-18 11:12       ` Peter Zijlstra
2022-03-15  7:39 ` Lai Jiangshan [this message]
2022-03-16 15:07   ` [PATCH V3 4/7] x86/entry: move PUSH_AND_CLEAR_REGS out of error_entry Peter Zijlstra
2022-03-16 16:18     ` Lai Jiangshan
2022-03-15  7:39 ` [PATCH V3 5/7] x86/entry: Move cld to the start of idtentry Lai Jiangshan
2022-03-15  7:39 ` [PATCH V3 6/7] x86/entry: Don't call error_entry for XENPV Lai Jiangshan
2022-03-16  2:59   ` Josh Poimboeuf
2022-03-16 15:09   ` Peter Zijlstra
2022-03-16 16:48     ` Lai Jiangshan
2022-03-15  7:39 ` [PATCH V3 7/7] x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS Lai Jiangshan
2022-03-16 15:12 ` [PATCH V3 0/7] x86/entry: Clean up entry code Peter Zijlstra
2022-03-16 15:13   ` Peter Zijlstra
2022-03-17 12:58     ` Lai Jiangshan

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