diff options
Diffstat (limited to 'kernel/arch/x86/boot/compressed/head_32.S')
| -rw-r--r-- | kernel/arch/x86/boot/compressed/head_32.S | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/kernel/arch/x86/boot/compressed/head_32.S b/kernel/arch/x86/boot/compressed/head_32.S index 8ef964ddc..0256064da 100644 --- a/kernel/arch/x86/boot/compressed/head_32.S +++ b/kernel/arch/x86/boot/compressed/head_32.S @@ -31,6 +31,34 @@ #include <asm/asm-offsets.h> #include <asm/bootparam.h> +/* + * The 32-bit x86 assembler in binutils 2.26 will generate R_386_GOT32X + * relocation to get the symbol address in PIC. When the compressed x86 + * kernel isn't built as PIC, the linker optimizes R_386_GOT32X + * relocations to their fixed symbol addresses. However, when the + * compressed x86 kernel is loaded at a different address, it leads + * to the following load failure: + * + * Failed to allocate space for phdrs + * + * during the decompression stage. + * + * If the compressed x86 kernel is relocatable at run-time, it should be + * compiled with -fPIE, instead of -fPIC, if possible and should be built as + * Position Independent Executable (PIE) so that linker won't optimize + * R_386_GOT32X relocation to its fixed symbol address. Older + * linkers generate R_386_32 relocations against locally defined symbols, + * _bss, _ebss, _got and _egot, in PIE. It isn't wrong, just less + * optimal than R_386_RELATIVE. But the x86 kernel fails to properly handle + * R_386_32 relocations when relocating the kernel. To generate + * R_386_RELATIVE relocations, we mark _bss, _ebss, _got and _egot as + * hidden: + */ + .hidden _bss + .hidden _ebss + .hidden _got + .hidden _egot + __HEAD ENTRY(startup_32) #ifdef CONFIG_EFI_STUB |