From: Ard Biesheuvel ardb@kernel.org
[ Commit 093ab258e3fb1d1d3afdfd4a69403d44ce90e360 upstream ]
The setup block contains the real mode startup code that is used when booting from a legacy BIOS, along with the boot_params/setup_data that is used by legacy x86 bootloaders to pass the command line and initial ramdisk parameters, among other things.
The setup block also contains the PE/COFF header of the entire combined image, which includes the compressed kernel image, the decompressor and the EFI stub.
This PE header describes the layout of the executable image in memory, and currently, the fact that the setup block precedes it makes it rather fiddly to get the right values into the right place in the final image.
Let's make things a bit easier by defining the setup_size in the linker script so it can be referenced from the asm code directly, rather than having to rely on the build tool to calculate it. For the time being, add 64 bytes of fixed padding for the .reloc and .compat sections - this will be removed in a subsequent patch after the PE/COFF header has been reorganized.
This change has no impact on the resulting bzImage binary when configured with CONFIG_EFI_MIXED=y.
Signed-off-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Link: https://lore.kernel.org/r/20230915171623.655440-13-ardb@google.com Signed-off-by: Ard Biesheuvel ardb@kernel.org --- arch/x86/boot/header.S | 2 +- arch/x86/boot/setup.ld | 4 ++++ arch/x86/boot/tools/build.c | 6 ------ 3 files changed, 5 insertions(+), 7 deletions(-)
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S index 34ab46b891e3..6dddf469ca60 100644 --- a/arch/x86/boot/header.S +++ b/arch/x86/boot/header.S @@ -230,7 +230,7 @@ sentinel: .byte 0xff, 0xff /* Used to detect broken loaders */
.globl hdr hdr: -setup_sects: .byte 0 /* Filled in by build.c */ + .byte setup_sects - 1 root_flags: .word ROOT_RDONLY syssize: .long 0 /* Filled in by build.c */ ram_size: .word 0 /* Obsolete */ diff --git a/arch/x86/boot/setup.ld b/arch/x86/boot/setup.ld index b11c45b9e51e..9bd5c1ada599 100644 --- a/arch/x86/boot/setup.ld +++ b/arch/x86/boot/setup.ld @@ -39,6 +39,10 @@ SECTIONS .signature : { setup_sig = .; LONG(0x5a5aaa55) + + /* Reserve some extra space for the reloc and compat sections */ + setup_size = ALIGN(ABSOLUTE(.) + 64, 512); + setup_sects = ABSOLUTE(setup_size / 512); }
diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c index 069497543164..745d64b6d930 100644 --- a/arch/x86/boot/tools/build.c +++ b/arch/x86/boot/tools/build.c @@ -48,12 +48,7 @@ typedef unsigned int u32; u8 buf[SETUP_SECT_MAX*512];
#define PECOFF_RELOC_RESERVE 0x20 - -#ifdef CONFIG_EFI_MIXED #define PECOFF_COMPAT_RESERVE 0x20 -#else -#define PECOFF_COMPAT_RESERVE 0x0 -#endif
static unsigned long efi_pe_entry; static unsigned long efi32_pe_entry; @@ -388,7 +383,6 @@ int main(int argc, char ** argv) #endif
/* Patch the setup code with the appropriate size parameters */ - buf[0x1f1] = setup_sectors-1; put_unaligned_le32(sys_size, &buf[0x1f4]);
update_pecoff_text(setup_sectors * 512, i + (sys_size * 16));