[PATCH v2 05/16] x86/compressed: efi-mixed: move efi32_entry out of head_64.S

Ard Biesheuvel
2022-09-21T14:55:02Z

Move the efi32_entry() routine out of head_64.S and into efi-mixed.S,
which reduces clutter in the complicated startup routines. It also
permits linkage of some symbols used by code to be made local.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/x86/boot/compressed/efi_mixed.S | 44 +++++++++++++++-----
arch/x86/boot/compressed/head_64.S | 32 --------------
2 files changed, 34 insertions(+), 42 deletions(-)

diff --git a/arch/x86/boot/compressed/efi_mixed.S b/arch/x86/boot/compressed/efi_mixed.S
index 77e77c3ea393..5007a44cd966 100644
--- a/arch/x86/boot/compressed/efi_mixed.S
+++ b/arch/x86/boot/compressed/efi_mixed.S
@@ -105,7 +105,7 @@ SYM_FUNC_START(__efi64_thunk)
/*
* Switch to IDT and GDT with 32-bit segments. This is the firmware GDT
* and IDT that was installed when the kernel started executing. The
- * pointers were saved at the EFI stub entry point in head_64.S.
+ * pointers were saved by the efi32_entry() routine below.
*
* Pass the saved DS selector to the 32-bit code, and use far return to
* restore the saved CS selector.
@@ -217,22 +217,46 @@ SYM_FUNC_START_LOCAL(efi_enter32)
lret
SYM_FUNC_END(efi_enter32)

+SYM_FUNC_START(efi32_entry)
+ call 1f
+1: pop %ebx
+
+ /* Save firmware GDTR and code/data selectors */
+ sgdtl (efi32_boot_gdt - 1b)(%ebx)
+ movw %cs, (efi32_boot_cs - 1b)(%ebx)
+ movw %ds, (efi32_boot_ds - 1b)(%ebx)
+
+ /* Store firmware IDT descriptor */
+ sidtl (efi32_boot_idt - 1b)(%ebx)
+
+ /* Store boot arguments */
+ leal (efi32_boot_args - 1b)(%ebx), %ebx
+ movl %ecx, 0(%ebx)
+ movl %edx, 4(%ebx)
+ movl %esi, 8(%ebx)
+ movb $0x0, 12(%ebx) // efi_is64
+
+ /* Disable paging */
+ movl %cr0, %eax
+ btrl $X86_CR0_PG_BIT, %eax
+ movl %eax, %cr0
+
+ jmp startup_32
+SYM_FUNC_END(efi32_entry)
+
.data
.balign 8
-SYM_DATA_START(efi32_boot_gdt)
+SYM_DATA_START_LOCAL(efi32_boot_gdt)
.word 0
.quad 0
SYM_DATA_END(efi32_boot_gdt)

-SYM_DATA_START(efi32_boot_idt)
+SYM_DATA_START_LOCAL(efi32_boot_idt)
.word 0
.quad 0
SYM_DATA_END(efi32_boot_idt)

-SYM_DATA_START(efi32_boot_cs)
- .word 0
-SYM_DATA_END(efi32_boot_cs)
-
-SYM_DATA_START(efi32_boot_ds)
- .word 0
-SYM_DATA_END(efi32_boot_ds)
+SYM_DATA_LOCAL(efi32_boot_cs, .word 0)
+SYM_DATA_LOCAL(efi32_boot_ds, .word 0)
+SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0)
+SYM_DATA(efi_is64, .byte 1)
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 9ae6ddccd3ef..be95d5685717 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -289,35 +289,6 @@ SYM_FUNC_START(efi32_stub_entry)
popl %esi
jmp efi32_entry
SYM_FUNC_END(efi32_stub_entry)
-
- .text
-SYM_FUNC_START_LOCAL(efi32_entry)
- call 1f
-1: pop %ebx
-
- /* Save firmware GDTR and code/data selectors */
- sgdtl (efi32_boot_gdt - 1b)(%ebx)
- movw %cs, (efi32_boot_cs - 1b)(%ebx)
- movw %ds, (efi32_boot_ds - 1b)(%ebx)
-
- /* Store firmware IDT descriptor */
- sidtl (efi32_boot_idt - 1b)(%ebx)
-
- /* Store boot arguments */
- leal (efi32_boot_args - 1b)(%ebx), %ebx
- movl %ecx, 0(%ebx)
- movl %edx, 4(%ebx)
- movl %esi, 8(%ebx)
- movb $0x0, 12(%ebx) // efi_is64
-
- /* Disable paging */
- movl %cr0, %eax
- btrl $X86_CR0_PG_BIT, %eax
- movl %eax, %cr0
-
- jmp startup_32
-SYM_FUNC_END(efi32_entry)
- __HEAD
#endif

.code64
@@ -750,9 +721,6 @@ SYM_DATA_END_LABEL(boot32_idt, SYM_L_GLOBAL, boot32_idt_end)
SYM_DATA(image_offset, .long 0)
#endif
#ifdef CONFIG_EFI_MIXED
-SYM_DATA(efi32_boot_args, .long 0, 0, 0)
-SYM_DATA(efi_is64, .byte 1)
-
#define ST32_boottime 60 // offsetof(efi_system_table_32_t, boottime)
#define BS32_handle_protocol 88 // offsetof(efi_boot_services_32_t, handle_protocol)
#define LI32_image_base 32 // offsetof(efi_loaded_image_32_t, image_base)
--
2.35.1