[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v2] Reduce assembly code size of exception entry points
We just pushed a 8-bytes zero and exception constants are small so we can just write a single byte saving 3 bytes for instruction. With ENDBR64 this reduces the size of many entry points from 32 to 16 bytes (due to alignment). Similar code is already used in autogen_stubs. Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxx> -- v2: - added missing entry points; - add mention to autogen_stubs code, as suggested. --- xen/arch/x86/x86_64/entry.S | 40 ++++++++++++++++++------------------- 1 file changed, 20 insertions(+), 20 deletions(-) diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S index ecdd6e5b47..a28a0d4044 100644 --- a/xen/arch/x86/x86_64/entry.S +++ b/xen/arch/x86/x86_64/entry.S @@ -389,7 +389,7 @@ FUNC(entry_int80) ENDBR64 ALTERNATIVE "", clac, X86_FEATURE_XEN_SMAP pushq $0 - movl $0x80, 4(%rsp) + movb $0x80, 4(%rsp) SAVE_ALL SPEC_CTRL_ENTRY_FROM_PV /* Req: %rsp=regs/cpuinfo, %rdx=0, Clob: acd */ @@ -653,7 +653,7 @@ END(ret_from_intr) .section .init.text, "ax", @progbits FUNC(early_page_fault) ENDBR64 - movl $X86_EXC_PF, 4(%rsp) + movb $X86_EXC_PF, 4(%rsp) SAVE_ALL movq %rsp, %rdi call do_early_page_fault @@ -898,105 +898,105 @@ END(handle_exception) FUNC(entry_DE) ENDBR64 pushq $0 - movl $X86_EXC_DE, 4(%rsp) + movb $X86_EXC_DE, 4(%rsp) jmp handle_exception END(entry_DE) FUNC(entry_MF) ENDBR64 pushq $0 - movl $X86_EXC_MF, 4(%rsp) + movb $X86_EXC_MF, 4(%rsp) jmp handle_exception END(entry_MF) FUNC(entry_XM) ENDBR64 pushq $0 - movl $X86_EXC_XM, 4(%rsp) + movb $X86_EXC_XM, 4(%rsp) jmp handle_exception END(entry_XM) FUNC(entry_NM) ENDBR64 pushq $0 - movl $X86_EXC_NM, 4(%rsp) + movb $X86_EXC_NM, 4(%rsp) jmp handle_exception END(entry_NM) FUNC(entry_DB) ENDBR64 pushq $0 - movl $X86_EXC_DB, 4(%rsp) + movb $X86_EXC_DB, 4(%rsp) jmp handle_ist_exception END(entry_DB) FUNC(entry_BP) ENDBR64 pushq $0 - movl $X86_EXC_BP, 4(%rsp) + movb $X86_EXC_BP, 4(%rsp) jmp handle_exception END(entry_BP) FUNC(entry_OF) ENDBR64 pushq $0 - movl $X86_EXC_OF, 4(%rsp) + movb $X86_EXC_OF, 4(%rsp) jmp handle_exception END(entry_OF) FUNC(entry_BR) ENDBR64 pushq $0 - movl $X86_EXC_BR, 4(%rsp) + movb $X86_EXC_BR, 4(%rsp) jmp handle_exception END(entry_BR) FUNC(entry_UD) ENDBR64 pushq $0 - movl $X86_EXC_UD, 4(%rsp) + movb $X86_EXC_UD, 4(%rsp) jmp handle_exception END(entry_UD) FUNC(entry_TS) ENDBR64 - movl $X86_EXC_TS, 4(%rsp) + movb $X86_EXC_TS, 4(%rsp) jmp handle_exception END(entry_TS) FUNC(entry_NP) ENDBR64 - movl $X86_EXC_NP, 4(%rsp) + movb $X86_EXC_NP, 4(%rsp) jmp handle_exception END(entry_NP) FUNC(entry_SS) ENDBR64 - movl $X86_EXC_SS, 4(%rsp) + movb $X86_EXC_SS, 4(%rsp) jmp handle_exception END(entry_SS) FUNC(entry_GP) ENDBR64 - movl $X86_EXC_GP, 4(%rsp) + movb $X86_EXC_GP, 4(%rsp) jmp handle_exception END(entry_GP) FUNC(entry_AC) ENDBR64 - movl $X86_EXC_AC, 4(%rsp) + movb $X86_EXC_AC, 4(%rsp) jmp handle_exception END(entry_AC) FUNC(entry_CP) ENDBR64 - movl $X86_EXC_CP, 4(%rsp) + movb $X86_EXC_CP, 4(%rsp) jmp handle_exception END(entry_CP) FUNC(entry_DF) ENDBR64 - movl $X86_EXC_DF, 4(%rsp) + movb $X86_EXC_DF, 4(%rsp) /* Set AC to reduce chance of further SMAP faults */ ALTERNATIVE "", stac, X86_FEATURE_XEN_SMAP SAVE_ALL @@ -1022,7 +1022,7 @@ END(entry_DF) FUNC(entry_NMI) ENDBR64 pushq $0 - movl $X86_EXC_NMI, 4(%rsp) + movb $X86_EXC_NMI, 4(%rsp) END(entry_NMI) FUNC(handle_ist_exception) @@ -1158,7 +1158,7 @@ END(handle_ist_exception) FUNC(entry_MC) ENDBR64 pushq $0 - movl $X86_EXC_MC, 4(%rsp) + movb $X86_EXC_MC, 4(%rsp) jmp handle_ist_exception END(entry_MC) -- 2.34.1
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