From f4dee0bb65752a1b5c9f7912bea8216f03667209 Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Thu, 24 Aug 2017 09:33:26 +0200 Subject: [PATCH] x86/boot/32: Extract efi_pe_entry() from startup_32() The efi_pe_entry() body is somehow squashed into startup_32(). In the old days, we forced startup_32() to start at offset 0x00 and efi_pe_entry() to start at 0x10. But this requirement was removed long time ago, in: 99f857db8857 ("x86, build: Dynamically find entry points in compressed startup code") The way it is now makes the code less readable and illogical. Given we can now safely extract the inlined efi_pe_entry() body from startup_32() into a separate function, we do so and we separate it to two functions as they are marked already: efi_pe_entry() + efi32_stub_entry(). We also annotate the functions appropriatelly by ENTRY+ENDPROC. ABI offset is preserved: 0000 128 FUNC GLOBAL DEFAULT 6 startup_32 0080 60 FUNC GLOBAL DEFAULT 6 efi_pe_entry 00bc 68 FUNC GLOBAL DEFAULT 6 efi32_stub_entry On the top-level, it looked like this: ENTRY(startup_32) #ifdef CONFIG_EFI_STUB ; start of inlined jmp preferred_addr ENTRY(efi_pe_entry) ... ; a lot of assembly (efi_pe_entry) ENTRY(efi32_stub_entry) ... ; a lot of assembly (efi32_stub_entry) leal preferred_addr(%eax), %eax jmp *%eax preferred_addr: #endif ; end of inlined ... ; a lot of assembly (startup_32) ENDPROC(startup_32) And it is now converted into: ENTRY(startup_32) ... ; a lot of assembly (startup_32) ENDPROC(startup_32) #ifdef CONFIG_EFI_STUB ENTRY(efi_pe_entry) ... ; a lot of assembly (efi_pe_entry) ENDPROC(efi_pe_entry) ENTRY(efi32_stub_entry) ... ; a lot of assembly (efi32_stub_entry) leal startup_32(%eax), %eax jmp *%eax ENDPROC(efi32_stub_entry) #endif Signed-off-by: Jiri Slaby Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: David Woodhouse Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Matt Fleming Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: ard.biesheuvel@linaro.org Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20170824073327.4129-1-jslaby@suse.cz Signed-off-by: Ingo Molnar --- arch/x86/boot/compressed/head_32.S | 129 ++++++++++++++++++------------------- 1 file changed, 64 insertions(+), 65 deletions(-) diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index d85b962..11c68cf 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -61,71 +61,6 @@ __HEAD ENTRY(startup_32) -#ifdef CONFIG_EFI_STUB - jmp preferred_addr - - /* - * We don't need the return address, so set up the stack so - * efi_main() can find its arguments. - */ -ENTRY(efi_pe_entry) - add $0x4, %esp - - call 1f -1: popl %esi - subl $1b, %esi - - popl %ecx - movl %ecx, efi32_config(%esi) /* Handle */ - popl %ecx - movl %ecx, efi32_config+8(%esi) /* EFI System table pointer */ - - /* Relocate efi_config->call() */ - leal efi32_config(%esi), %eax - add %esi, 40(%eax) - pushl %eax - - call make_boot_params - cmpl $0, %eax - je fail - movl %esi, BP_code32_start(%eax) - popl %ecx - pushl %eax - pushl %ecx - jmp 2f /* Skip efi_config initialization */ - -ENTRY(efi32_stub_entry) - add $0x4, %esp - popl %ecx - popl %edx - - call 1f -1: popl %esi - subl $1b, %esi - - movl %ecx, efi32_config(%esi) /* Handle */ - movl %edx, efi32_config+8(%esi) /* EFI System table pointer */ - - /* Relocate efi_config->call() */ - leal efi32_config(%esi), %eax - add %esi, 40(%eax) - pushl %eax -2: - call efi_main - cmpl $0, %eax - movl %eax, %esi - jne 2f -fail: - /* EFI init failed, so hang. */ - hlt - jmp fail -2: - movl BP_code32_start(%esi), %eax - leal preferred_addr(%eax), %eax - jmp *%eax - -preferred_addr: -#endif cld /* * Test KEEP_SEGMENTS flag to see if the bootloader is asking @@ -208,6 +143,70 @@ preferred_addr: jmp *%eax ENDPROC(startup_32) +#ifdef CONFIG_EFI_STUB +/* + * We don't need the return address, so set up the stack so efi_main() can find + * its arguments. + */ +ENTRY(efi_pe_entry) + add $0x4, %esp + + call 1f +1: popl %esi + subl $1b, %esi + + popl %ecx + movl %ecx, efi32_config(%esi) /* Handle */ + popl %ecx + movl %ecx, efi32_config+8(%esi) /* EFI System table pointer */ + + /* Relocate efi_config->call() */ + leal efi32_config(%esi), %eax + add %esi, 40(%eax) + pushl %eax + + call make_boot_params + cmpl $0, %eax + je fail + movl %esi, BP_code32_start(%eax) + popl %ecx + pushl %eax + pushl %ecx + jmp 2f /* Skip efi_config initialization */ +ENDPROC(efi_pe_entry) + +ENTRY(efi32_stub_entry) + add $0x4, %esp + popl %ecx + popl %edx + + call 1f +1: popl %esi + subl $1b, %esi + + movl %ecx, efi32_config(%esi) /* Handle */ + movl %edx, efi32_config+8(%esi) /* EFI System table pointer */ + + /* Relocate efi_config->call() */ + leal efi32_config(%esi), %eax + add %esi, 40(%eax) + pushl %eax +2: + call efi_main + cmpl $0, %eax + movl %eax, %esi + jne 2f +fail: + /* EFI init failed, so hang. */ + hlt + jmp fail +2: + movl BP_code32_start(%esi), %eax + leal startup_32(%eax), %eax + jmp *%eax +ENDPROC(efi32_stub_entry) +#endif + .text relocated: -- 2.7.4