The mixed mode refactor actually broke mixed mode by failing to pass the bootparam structure to startup_32(). This went unnoticed because it apparently has a high tolerance for being passed random junk, and still boots fine in some cases. So let's fix this by populating %esi as required when entering via efi32_stub_entry, and while at it, preserve the arguments themselves instead of their address in memory (via the stack pointer) since that memory could be clobbered before we get to it. Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> --- arch/x86/boot/compressed/head_64.S | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index a6f3ee9ca61d..44a6bb6964b5 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -208,13 +208,12 @@ SYM_FUNC_START(startup_32) pushl $__KERNEL_CS leal startup_64(%ebp), %eax #ifdef CONFIG_EFI_MIXED - movl efi32_boot_args(%ebp), %ebx - cmp $0, %ebx + movl efi32_boot_args(%ebp), %edi + cmp $0, %edi jz 1f leal handover_entry(%ebp), %eax - movl 0(%ebx), %edi - movl 4(%ebx), %esi - movl 8(%ebx), %edx + movl %esi, %edx + movl efi32_boot_args+4(%ebp), %esi movl $0x0, %ecx 1: #endif @@ -232,12 +231,16 @@ SYM_FUNC_END(startup_32) .org 0x190 SYM_FUNC_START(efi32_stub_entry) add $0x4, %esp /* Discard return address */ + popl %ecx + popl %edx + popl %esi call 1f 1: pop %ebp subl $1b, %ebp - movl %esp, efi32_boot_args(%ebp) + movl %ecx, efi32_boot_args(%ebp) + movl %edx, efi32_boot_args+4(%ebp) sgdtl efi32_boot_gdt(%ebp) /* Disable paging */ @@ -628,7 +631,7 @@ SYM_DATA_START_LOCAL(gdt) SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end) #ifdef CONFIG_EFI_MIXED -SYM_DATA_LOCAL(efi32_boot_args, .long 0) +SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0) #endif /* -- 2.20.1
