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x86/efi: Fixup GOT in all boot code paths

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Maarten reported that his Macbook pro 8.2 stopped booting after commit
f23cf8bd5c ("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>
This commit is contained in:
Matt Fleming
2014-09-05 14:52:26 +01:00
parent 47226ad4f4
commit 9cb0e39423
2 changed files with 81 additions and 29 deletions
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56
arch/x86/boot/compressed/head_64.S
View File

@@ -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