From 9cb0e394234d244fe5a97e743ec9dd7ddff7e64b Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Fri, 5 Sep 2014 14:52:26 +0100 Subject: [PATCH] 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 "), 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 Tested-by: Maarten Lankhorst Cc: Ard Biesheuvel Signed-off-by: Matt Fleming --- arch/x86/boot/compressed/head_32.S | 54 ++++++++++++++++++++-------- arch/x86/boot/compressed/head_64.S | 56 ++++++++++++++++++++++-------- 2 files changed, 81 insertions(+), 29 deletions(-) diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index cbed1407a5cd..d6b8aa4c986c 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -30,6 +30,33 @@ #include #include +/* + * Adjust our own GOT + * + * The relocation base must be in %ebx + * + * 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(%ebx) + je 2f + + leal _got(%ebx), %edx + leal _egot(%ebx), %ecx +1: + cmpl %ecx, %edx + jae 2f + addl %ebx, (%edx) + addl $4, %edx + jmp 1b +2: + movb $1, got_fixed(%ebx) +.endm + __HEAD ENTRY(startup_32) #ifdef CONFIG_EFI_STUB @@ -56,6 +83,9 @@ ENTRY(efi_pe_entry) add %esi, 88(%eax) pushl %eax + movl %esi, %ebx + FIXUP_GOT + call make_boot_params cmpl $0, %eax je fail @@ -81,6 +111,10 @@ ENTRY(efi32_stub_entry) leal efi32_config(%esi), %eax add %esi, 88(%eax) pushl %eax + + movl %esi, %ebx + FIXUP_GOT + 2: call efi_main cmpl $0, %eax @@ -190,19 +224,7 @@ relocated: shrl $2, %ecx rep stosl -/* - * Adjust our own GOT - */ - leal _got(%ebx), %edx - leal _egot(%ebx), %ecx -1: - cmpl %ecx, %edx - jae 2f - addl %ebx, (%edx) - addl $4, %edx - jmp 1b -2: - + FIXUP_GOT /* * Do the decompression, and jump to the new kernel.. */ @@ -225,8 +247,12 @@ relocated: xorl %ebx, %ebx jmp *%eax -#ifdef CONFIG_EFI_STUB .data +/* Have we relocated the GOT? */ +got_fixed: + .byte 0 + +#ifdef CONFIG_EFI_STUB efi32_config: .fill 11,8,0 .long efi_call_phys 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 #include +/* + * 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 -- 2.39.2