From: Ard Biesheuvel Date: Fri, 15 Sep 2023 17:16:28 +0000 (+0000) Subject: x86/boot: Derive file size from _edata symbol X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=aeb92067f6ae994b541d7f9752fe54ed3d108bcc;p=linux.git x86/boot: Derive file size from _edata symbol Tweak the linker script so that the value of _edata represents the decompressor binary's file size rounded up to the appropriate alignment. This removes the need to calculate it in the build tool, and will make it easier to refer to the file size from the header directly in subsequent changes to the PE header layout. While adding _edata to the sed regex that parses the compressed vmlinux's symbol list, tweak the regex a bit for conciseness. This change has no impact on the resulting bzImage binary when configured with CONFIG_EFI_STUB=y. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230915171623.655440-14-ardb@google.com --- diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile index 0e98bc5036994..cc04917b1ac68 100644 --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -89,7 +89,7 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE SETUP_OBJS = $(addprefix $(obj)/,$(setup-y)) -sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi32_stub_entry\|efi64_stub_entry\|efi_pe_entry\|efi32_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|z_.*\)$$/\#define ZO_\2 0x\1/p' +sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_edata\|z_.*\)$$/\#define ZO_\2 0x\1/p' quiet_cmd_zoffset = ZOFFSET $@ cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@ diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S index 4ff6ab1b67d9b..b688598db28e3 100644 --- a/arch/x86/boot/compressed/vmlinux.lds.S +++ b/arch/x86/boot/compressed/vmlinux.lds.S @@ -47,6 +47,9 @@ SECTIONS _data = . ; *(.data) *(.data.*) + + /* Add 4 bytes of extra space for a CRC-32 checksum */ + . = ALIGN(. + 4, 0x20); _edata = . ; } . = ALIGN(L1_CACHE_BYTES); diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S index 06bd72a324c11..34e9b35b827cf 100644 --- a/arch/x86/boot/header.S +++ b/arch/x86/boot/header.S @@ -233,7 +233,7 @@ sentinel: .byte 0xff, 0xff /* Used to detect broken loaders */ hdr: .byte setup_sects - 1 root_flags: .word ROOT_RDONLY -syssize: .long 0 /* Filled in by build.c */ +syssize: .long ZO__edata / 16 ram_size: .word 0 /* Obsolete */ vid_mode: .word SVGA_MODE root_dev: .word 0 /* Default to major/minor 0/0 */ diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c index 745d64b6d9303..e792c6c5a634d 100644 --- a/arch/x86/boot/tools/build.c +++ b/arch/x86/boot/tools/build.c @@ -52,6 +52,7 @@ u8 buf[SETUP_SECT_MAX*512]; static unsigned long efi_pe_entry; static unsigned long efi32_pe_entry; +static unsigned long _edata; static unsigned long _end; /*----------------------------------------------------------------------*/ @@ -308,6 +309,7 @@ static void parse_zoffset(char *fname) while (p && *p) { PARSE_ZOFS(p, efi_pe_entry); PARSE_ZOFS(p, efi32_pe_entry); + PARSE_ZOFS(p, _edata); PARSE_ZOFS(p, _end); p = strchr(p, '\n'); @@ -320,7 +322,6 @@ int main(int argc, char ** argv) { unsigned int i, sz, setup_sectors; int c; - u32 sys_size; struct stat sb; FILE *file, *dest; int fd; @@ -368,24 +369,14 @@ int main(int argc, char ** argv) die("Unable to open `%s': %m", argv[2]); if (fstat(fd, &sb)) die("Unable to stat `%s': %m", argv[2]); - sz = sb.st_size; + if (_edata != sb.st_size) + die("Unexpected file size `%s': %u != %u", argv[2], _edata, + sb.st_size); + sz = _edata - 4; kernel = mmap(NULL, sz, PROT_READ, MAP_SHARED, fd, 0); if (kernel == MAP_FAILED) die("Unable to mmap '%s': %m", argv[2]); - /* Number of 16-byte paragraphs, including space for a 4-byte CRC */ - sys_size = (sz + 15 + 4) / 16; -#ifdef CONFIG_EFI_STUB - /* - * COFF requires minimum 32-byte alignment of sections, and - * adding a signature is problematic without that alignment. - */ - sys_size = (sys_size + 1) & ~1; -#endif - - /* Patch the setup code with the appropriate size parameters */ - put_unaligned_le32(sys_size, &buf[0x1f4]); - - update_pecoff_text(setup_sectors * 512, i + (sys_size * 16)); + update_pecoff_text(setup_sectors * 512, i + _edata); crc = partial_crc32(buf, i, crc); @@ -397,13 +388,6 @@ int main(int argc, char ** argv) if (fwrite(kernel, 1, sz, dest) != sz) die("Writing kernel failed"); - /* Add padding leaving 4 bytes for the checksum */ - while (sz++ < (sys_size*16) - 4) { - crc = partial_crc32_one('\0', crc); - if (fwrite("\0", 1, 1, dest) != 1) - die("Writing padding failed"); - } - /* Write the CRC */ put_unaligned_le32(crc, buf); if (fwrite(buf, 1, 4, dest) != 4)