[PATCH 6.1 119/215] x86/boot/compressed: Pull global variable reference into startup32_load_idt()

Greg Kroah-Hartman
2024-03-04T21:49:35Z

From: Ard Biesheuvel <ardb@kernel.org>

commit d73a257f7f86871c3aac24dc20538e3983096647 upstream.

In preparation for moving startup32_load_idt() out of head_64.S and
turning it into an ordinary function using the ordinary 32-bit calling
convention, pull the global variable reference to boot32_idt up into
startup32_load_idt() so that startup32_set_idt_entry() does not need to
discover its own runtime physical address, which will no longer be
correlated with startup_32 once this code is moved into .text.

While at it, give startup32_set_idt_entry() static linkage.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221122161017.2426828-11-ardb@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/boot/compressed/head_64.S | 20 ++++++++------------
1 file changed, 8 insertions(+), 12 deletions(-)

--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -744,16 +744,11 @@ SYM_DATA_END_LABEL(boot32_idt, SYM_L_GLO
*
* %eax: Handler address
* %edx: Vector number
- *
- * Physical offset is expected in %ebp
+ * %ecx: IDT address
*/
-SYM_FUNC_START(startup32_set_idt_entry)
- push %ebx
-
- /* IDT entry address to %ebx */
- leal rva(boot32_idt)(%ebp), %ebx
- shl $3, %edx
- addl %edx, %ebx
+SYM_FUNC_START_LOCAL(startup32_set_idt_entry)
+ /* IDT entry address to %ecx */
+ leal (%ecx, %edx, 8), %ecx

/* Build IDT entry, lower 4 bytes */
movl %eax, %edx
@@ -761,7 +756,7 @@ SYM_FUNC_START(startup32_set_idt_entry)
orl $(__KERNEL32_CS << 16), %edx # Target code segment selector

/* Store lower 4 bytes to IDT */
- movl %edx, (%ebx)
+ movl %edx, (%ecx)

/* Build IDT entry, upper 4 bytes */
movl %eax, %edx
@@ -769,15 +764,16 @@ SYM_FUNC_START(startup32_set_idt_entry)
orl $0x00008e00, %edx # Present, Type 32-bit Interrupt Gate

/* Store upper 4 bytes to IDT */
- movl %edx, 4(%ebx)
+ movl %edx, 4(%ecx)

- pop %ebx
RET
SYM_FUNC_END(startup32_set_idt_entry)
#endif

SYM_FUNC_START(startup32_load_idt)
#ifdef CONFIG_AMD_MEM_ENCRYPT
+ leal rva(boot32_idt)(%ebp), %ecx
+
/* #VC handler */
leal rva(startup32_vc_handler)(%ebp), %eax
movl $X86_TRAP_VC, %edx