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x86/boot/compressed: Move startup32_load_idt() into .text section

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commit c6355995ba471d7ad574174e593192ce805c7e1a upstream.

Convert startup32_load_idt() into an ordinary function and move it into
the .text section. This involves turning the rva() immediates into ones
derived from a local label, and preserving/restoring the %ebp and %ebx
as per the calling convention.

Also move the #ifdef to the only existing call site. This makes it clear
that the function call does nothing if support for memory encryption is
not compiled in.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221122161017.2426828-12-ardb@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ard Biesheuvel 2022-11-22 17:10:11 +01:00 committed by Greg Kroah-Hartman
parent 29134968f7
commit 2e47116315
1 changed files with 20 additions and 11 deletions
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31
arch/x86/boot/compressed/head_64.S
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@ -118,7 +118,9 @@ SYM_FUNC_START(startup_32)
1:
/* Setup Exception handling for SEV-ES */
#ifdef CONFIG_AMD_MEM_ENCRYPT
call startup32_load_idt
#endif
/* Make sure cpu supports long mode. */
call verify_cpu
@ -732,10 +734,8 @@ SYM_DATA_START(boot32_idt)
.quad 0
.endr
SYM_DATA_END_LABEL(boot32_idt, SYM_L_GLOBAL, boot32_idt_end)
#endif
#ifdef CONFIG_AMD_MEM_ENCRYPT
__HEAD
.text
.code32
/*
* Write an IDT entry into boot32_idt
@ -768,24 +768,32 @@ SYM_FUNC_START_LOCAL(startup32_set_idt_entry)
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
push %ebp
push %ebx
call 1f
1: pop %ebp
leal (boot32_idt - 1b)(%ebp), %ebx
/* #VC handler */
leal rva(startup32_vc_handler)(%ebp), %eax
leal (startup32_vc_handler - 1b)(%ebp), %eax
movl $X86_TRAP_VC, %edx
movl %ebx, %ecx
call startup32_set_idt_entry
/* Load IDT */
leal rva(boot32_idt)(%ebp), %eax
movl %eax, rva(boot32_idt_desc+2)(%ebp)
lidt rva(boot32_idt_desc)(%ebp)
#endif
leal (boot32_idt_desc - 1b)(%ebp), %ecx
movl %ebx, 2(%ecx)
lidt (%ecx)
pop %ebx
pop %ebp
RET
SYM_FUNC_END(startup32_load_idt)
#endif
/*
* Check for the correct C-bit position when the startup_32 boot-path is used.
@ -804,6 +812,7 @@ SYM_FUNC_END(startup32_load_idt)
* succeed. An incorrect C-bit position will map all memory unencrypted, so that
* the compare will use the encrypted random data and fail.
*/
__HEAD
SYM_FUNC_START(startup32_check_sev_cbit)
#ifdef CONFIG_AMD_MEM_ENCRYPT
pushl %eax