diff options
Diffstat (limited to 'arch/x86/boot/compressed')
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 68 |
1 files changed, 55 insertions, 13 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index fca012baba19..d17af6a4bfc9 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -306,6 +306,25 @@ ENTRY(startup_64) leaq boot_stack_end(%rbx), %rsp /* + * paging_prepare() and cleanup_trampoline() below can have GOT + * references. Adjust the table with address we are running at. + * + * Zero RAX for adjust_got: the GOT was not adjusted before; + * there's no adjustment to undo. + */ + xorq %rax, %rax + + /* + * Calculate the address the binary is loaded at and use it as + * a GOT adjustment. + */ + call 1f +1: popq %rdi + subq $1b, %rdi + + call adjust_got + + /* * At this point we are in long mode with 4-level paging enabled, * but we might want to enable 5-level paging or vice versa. * @@ -381,6 +400,21 @@ trampoline_return: pushq $0 popfq + /* + * Previously we've adjusted the GOT with address the binary was + * loaded at. Now we need to re-adjust for relocation address. + * + * Calculate the address the binary is loaded at, so that we can + * undo the previous GOT adjustment. + */ + call 1f +1: popq %rax + subq $1b, %rax + + /* The new adjustment is the relocation address */ + movq %rbx, %rdi + call adjust_got + /* * Copy the compressed kernel to the end of our buffer * where decompression in place becomes safe. @@ -482,19 +516,6 @@ relocated: 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: - -/* * Do the extraction, and jump to the new kernel.. */ pushq %rsi /* Save the real mode argument */ @@ -512,6 +533,27 @@ relocated: */ jmp *%rax +/* + * Adjust the global offset table + * + * RAX is the previous adjustment of the table to undo (use 0 if it's the + * first time we touch GOT). + * RDI is the new adjustment to apply. + */ +adjust_got: + /* Walk through the GOT adding the address to the entries */ + leaq _got(%rip), %rdx + leaq _egot(%rip), %rcx +1: + cmpq %rcx, %rdx + jae 2f + subq %rax, (%rdx) /* Undo previous adjustment */ + addq %rdi, (%rdx) /* Apply the new adjustment */ + addq $8, %rdx + jmp 1b +2: + ret + .code32 /* * This is the 32-bit trampoline that will be copied over to low memory. |