From 7e8213c1f3acc064aef37813a39f13cbfe7c3ce7 Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Tue, 8 Apr 2014 13:14:00 +0100 Subject: x86/efi: Correct EFI boot stub use of code32_start MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit code32_start should point at the start of the protected mode code, and *not* at the beginning of the bzImage. This is much easier to do in assembly so document that callers of make_boot_params() need to fill out code32_start. The fallout from this bug is that we would end up relocating the image but copying the image at some offset, resulting in what appeared to be memory corruption. Reported-by: Thomas Bächler Signed-off-by: Matt Fleming --- arch/x86/boot/compressed/eboot.c | 5 +++-- arch/x86/boot/compressed/head_32.S | 8 ++------ arch/x86/boot/compressed/head_64.S | 9 +++------ 3 files changed, 8 insertions(+), 14 deletions(-) (limited to 'arch/x86/boot') diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c index 280165524ee4..91d17007323b 100644 --- a/arch/x86/boot/compressed/eboot.c +++ b/arch/x86/boot/compressed/eboot.c @@ -1016,6 +1016,9 @@ void setup_graphics(struct boot_params *boot_params) * Because the x86 boot code expects to be passed a boot_params we * need to create one ourselves (usually the bootloader would create * one for us). + * + * The caller is responsible for filling out ->code32_start in the + * returned boot_params. */ struct boot_params *make_boot_params(struct efi_config *c) { @@ -1081,8 +1084,6 @@ struct boot_params *make_boot_params(struct efi_config *c) hdr->vid_mode = 0xffff; hdr->boot_flag = 0xAA55; - hdr->code32_start = (__u64)(unsigned long)image->image_base; - hdr->type_of_loader = 0x21; /* Convert unicode cmdline to ascii */ diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index de9d4200d305..cbed1407a5cd 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -59,6 +59,7 @@ ENTRY(efi_pe_entry) call make_boot_params cmpl $0, %eax je fail + movl %esi, BP_code32_start(%eax) popl %ecx pushl %eax pushl %ecx @@ -90,12 +91,7 @@ fail: hlt jmp fail 2: - call 3f -3: - popl %eax - subl $3b, %eax - subl BP_pref_address(%esi), %eax - add BP_code32_start(%esi), %eax + movl BP_code32_start(%esi), %eax leal preferred_addr(%eax), %eax jmp *%eax diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 57e58a5fa210..0d558ee899ae 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -261,6 +261,8 @@ ENTRY(efi_pe_entry) cmpq $0,%rax je fail mov %rax, %rsi + leaq startup_32(%rip), %rax + movl %eax, BP_code32_start(%rsi) jmp 2f /* Skip the relocation */ handover_entry: @@ -284,12 +286,7 @@ fail: hlt jmp fail 2: - call 3f -3: - popq %rax - subq $3b, %rax - subq BP_pref_address(%rsi), %rax - add BP_code32_start(%esi), %eax + movl BP_code32_start(%esi), %eax leaq preferred_addr(%rax), %rax jmp *%rax -- cgit v1.2.3