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x86/boot/compressed: Adhere to calling convention in get_sev_encryption_bit()

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Make get_sev_encryption_bit() follow the ordinary i386 calling
convention, and only call it if CONFIG_AMD_MEM_ENCRYPT is actually
enabled. This clarifies the calling code, and makes it more
maintainable.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221122161017.2426828-16-ardb@kernel.org
This commit is contained in:
Ard Biesheuvel 2022-11-22 17:10:15 +01:00 committed by Borislav Petkov
parent 9d7eaae6a0
commit 30c9ca16a5
2 changed files with 3 additions and 12 deletions
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5
arch/x86/boot/compressed/head_64.S
View File

@ -180,12 +180,13 @@ SYM_FUNC_START(startup_32)
*/
/*
* If SEV is active then set the encryption mask in the page tables.
* This will insure that when the kernel is copied and decompressed
* This will ensure that when the kernel is copied and decompressed
* it will be done so encrypted.
*/
call get_sev_encryption_bit
xorl %edx, %edx
#ifdef CONFIG_AMD_MEM_ENCRYPT
call get_sev_encryption_bit
xorl %edx, %edx
testl %eax, %eax
jz 1f
subl $32, %eax /* Encryption bit is always above bit 31 */

10
arch/x86/boot/compressed/mem_encrypt.S
View File

@ -18,12 +18,7 @@
.text
.code32
SYM_FUNC_START(get_sev_encryption_bit)
xor %eax, %eax
#ifdef CONFIG_AMD_MEM_ENCRYPT
push %ebx
push %ecx
push %edx
movl $0x80000000, %eax /* CPUID to check the highest leaf */
cpuid
@ -54,12 +49,7 @@ SYM_FUNC_START(get_sev_encryption_bit)
xor %eax, %eax
.Lsev_exit:
pop %edx
pop %ecx
pop %ebx
#endif /* CONFIG_AMD_MEM_ENCRYPT */
RET
SYM_FUNC_END(get_sev_encryption_bit)