diff options
| author | Matt Fleming <matt.fleming@intel.com> | 2014-09-05 14:52:26 +0100 |
|---|---|---|
| committer | Matt Fleming <matt.fleming@intel.com> | 2014-09-08 20:52:02 +0100 |
| commit | 9cb0e394234d244fe5a97e743ec9dd7ddff7e64b (patch) | |
| tree | 4828f610aab906bd7f4190ac32da0f777271480c /arch/x86/boot/compressed/head_64.S | |
| parent | 47226ad4f4cfd1e91ded7f2ec42f83ff1c624663 (diff) | |
x86/efi: Fixup GOT in all boot code paths
Maarten reported that his Macbook pro 8.2 stopped booting after commit
f23cf8bd5c1f49 ("efi/x86: efistub: Move shared dependencies to
<asm/efi.h>"), the main feature of which is changing the visibility of
symbol 'efi_early' from local to global.
By making 'efi_early' global we end up requiring an entry in the Global
Offset Table. Unfortunately, while we do include code to fixup GOT
entries in the early boot code, it's only called after we've executed
the EFI boot stub.
What this amounts to is that references to 'efi_early' in the EFI boot
stub don't point to the correct place.
Since we've got multiple boot entry points we need to be prepared to
fixup the GOT in multiple places, while ensuring that we never do it
more than once, otherwise the GOT entries will still point to the wrong
place.
Reported-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Tested-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Diffstat (limited to 'arch/x86/boot/compressed/head_64.S')
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 56 |
1 files changed, 41 insertions, 15 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 2884e0c3e8a5..50f69c7eaaf4 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -32,6 +32,33 @@ #include <asm/processor-flags.h> #include <asm/asm-offsets.h> +/* + * Adjust our own GOT + * + * The relocation base must be in %rbx + * + * It is safe to call this macro more than once, because in some of the + * code paths multiple invocations are inevitable, e.g. via the efi* + * entry points. + * + * Relocation is only performed the first time. + */ +.macro FIXUP_GOT + cmpb $1, got_fixed(%rip) + je 2f + + leaq _got(%rip), %rdx + leaq _egot(%rip), %rcx +1: + cmpq %rcx, %rdx + jae 2f + addq %rbx, (%rdx) + addq $8, %rdx + jmp 1b +2: + movb $1, got_fixed(%rip) +.endm + __HEAD .code32 ENTRY(startup_32) @@ -252,10 +279,13 @@ ENTRY(efi_pe_entry) subq $1b, %rbp /* - * Relocate efi_config->call(). + * Relocate efi_config->call() and the GOT entries. */ addq %rbp, efi64_config+88(%rip) + movq %rbp, %rbx + FIXUP_GOT + movq %rax, %rdi call make_boot_params cmpq $0,%rax @@ -271,10 +301,13 @@ handover_entry: subq $1b, %rbp /* - * Relocate efi_config->call(). + * Relocate efi_config->call() and the GOT entries. */ movq efi_config(%rip), %rax addq %rbp, 88(%rax) + + movq %rbp, %rbx + FIXUP_GOT 2: movq efi_config(%rip), %rdi call efi_main @@ -385,19 +418,8 @@ relocated: shrq $3, %rcx rep stosq -/* - * Adjust our own GOT - */ - leaq _got(%rip), %rdx - leaq _egot(%rip), %rcx -1: - cmpq %rcx, %rdx - jae 2f - addq %rbx, (%rdx) - addq $8, %rdx - jmp 1b -2: - + FIXUP_GOT + /* * Do the decompression, and jump to the new kernel.. */ @@ -437,6 +459,10 @@ gdt: .quad 0x0000000000000000 /* TS continued */ gdt_end: +/* Have we relocated the GOT? */ +got_fixed: + .byte 0 + #ifdef CONFIG_EFI_STUB efi_config: .quad 0 |