@@ -457,18 +457,9 @@ SYM_CODE_START(startup_64)
/* Save the trampoline address in RCX */
movq %rax, %rcx
- /*
- * Load the address of trampoline_return() into RDI.
- * It will be used by the trampoline to return to the main code.
- */
- leaq trampoline_return(%rip), %rdi
-
- /* Switch to compatibility mode (CS.L = 0 CS.D = 1) via far return */
- pushq $__KERNEL32_CS
leaq TRAMPOLINE_32BIT_CODE_OFFSET(%rax), %rax
- pushq %rax
- lretq
-trampoline_return:
+ call *%rax
+
/* Restore the stack, the 32-bit trampoline uses its own stack */
leaq rva(boot_stack_end)(%rbx), %rsp
@@ -566,16 +557,22 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
jmp *%rax
SYM_FUNC_END(.Lrelocated)
- .code32
/*
* This is the 32-bit trampoline that will be copied over to low memory.
*
- * RDI contains the return address (might be above 4G).
* ECX contains the base address of the trampoline memory.
* Non zero RDX means trampoline needs to enable 5-level paging.
*/
SYM_CODE_START(trampoline_32bit_src)
- /* Set up data and stack segments */
+ popq %rdi
+ /* Switch to compatibility mode (CS.L = 0 CS.D = 1) via far return */
+ pushq $__KERNEL32_CS
+ leaq 0f(%rip), %rax
+ pushq %rax
+ lretq
+
+ .code32
+0: /* Set up data and stack segments */
movl $__KERNEL_DS, %eax
movl %eax, %ds
movl %eax, %ss
@@ -6,7 +6,7 @@
#define TRAMPOLINE_32BIT_PGTABLE_OFFSET 0
#define TRAMPOLINE_32BIT_CODE_OFFSET PAGE_SIZE
-#define TRAMPOLINE_32BIT_CODE_SIZE 0x80
+#define TRAMPOLINE_32BIT_CODE_SIZE 0xA0
#define TRAMPOLINE_32BIT_STACK_END TRAMPOLINE_32BIT_SIZE
Move the long return to switch to 32-bit mode into the trampoline code so we can call it as an ordinary function. This will allow us to call it directly from C code in a subsequent patch. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- arch/x86/boot/compressed/head_64.S | 25 +++++++++----------- arch/x86/boot/compressed/pgtable.h | 2 +- 2 files changed, 12 insertions(+), 15 deletions(-)