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Peter Anvin" 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 Message-Id: <20220315073949.7541-5-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20220315073949.7541-1-jiangshanlai@gmail.com> References: <20220315073949.7541-1-jiangshanlai@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lai Jiangshan 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 --- 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