On Mon, 2 Mar 2020 at 00:04, Arvind Sankar <nivedita@xxxxxxxxxxxx> wrote: > > Setup a proper frame pointer in efi32_pe_entry so that it's easier to > calculate offsets for arguments. > > Signed-off-by: Arvind Sankar <nivedita@xxxxxxxxxxxx> > --- > arch/x86/boot/compressed/head_64.S | 57 +++++++++++++++++++++--------- > 1 file changed, 40 insertions(+), 17 deletions(-) > > diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S > index 920daf62dac2..fabbd4c2e9f2 100644 > --- a/arch/x86/boot/compressed/head_64.S > +++ b/arch/x86/boot/compressed/head_64.S > @@ -658,42 +658,65 @@ SYM_DATA(efi_is64, .byte 1) > .text > .code32 > SYM_FUNC_START(efi32_pe_entry) > +/* > + * efi_status_t efi32_pe_entry(efi_handle_t image_handle, > + * efi_system_table_32_t *sys_table) > + */ > + > pushl %ebp > + movl %esp, %ebp > + pushl %eax // dummy push to allocate loaded_image > > - pushl %ebx > + pushl %ebx // save callee-save registers > pushl %edi > + > call verify_cpu // check for long mode support > - popl %edi > - popl %ebx > testl %eax, %eax > movl $0x80000003, %eax // EFI_UNSUPPORTED > - jnz 3f > + jnz 2f > > call 1f > -1: pop %ebp > - subl $1b, %ebp > +1: pop %ebx > + subl $1b, %ebx > > /* Get the loaded image protocol pointer from the image handle */ > - subl $12, %esp // space for the loaded image pointer > - pushl %esp // pass its address > - leal loaded_image_proto(%ebp), %eax > + leal -4(%ebp), %eax > + pushl %eax // &loaded_image > + leal loaded_image_proto(%ebx), %eax > pushl %eax // pass the GUID address > - pushl 28(%esp) // pass the image handle > + pushl 8(%ebp) // pass the image handle > > - movl 36(%esp), %eax // sys_table > + /* > + * Note the alignment of the stack frame. > + * sys_table > + * handle <-- 16-byte aligned on entry by ABI > + * return address > + * frame pointer > + * loaded_image <-- local variable > + * saved %ebx <-- 16-byte aligned here > + * saved %edi > + * &loaded_image > + * &loaded_image_proto > + * handle <-- 16-byte aligned for call to handle_protocol > + */ > + > + movl 12(%ebp), %eax // sys_table > movl ST32_boottime(%eax), %eax // sys_table->boottime > call *BS32_handle_protocol(%eax) // sys_table->boottime->handle_protocol > - cmp $0, %eax > + addl $12, %esp // restore argument space > + testl %eax, %eax > jnz 2f > > - movl 32(%esp), %ecx // image_handle > - movl 36(%esp), %edx // sys_table > - movl 12(%esp), %esi // loaded_image > + movl 8(%ebp), %ecx // image_handle > + movl 12(%ebp), %edx // sys_table > + movl -4(%ebp), %esi // loaded_image > movl LI32_image_base(%esi), %esi // loaded_image->image_base > + movl %ebx, %ebp // startup_32 for efi32_pe_stub_entry The code that follows efi32_pe_stub_entry still expects the runtime displacement in %ebp, so we'll need to pass that in another way here. > jmp efi32_pe_stub_entry > > -2: addl $24, %esp > -3: popl %ebp > +2: popl %edi // restore callee-save registers > + popl %ebx > + leave > ret > SYM_FUNC_END(efi32_pe_entry) > > -- > 2.24.1 >
