diff options
| author |  Ard Biesheuvel <ardb@kernel.org>
| 2023-08-07 18:27:07 +0200 |
|---|---|---|
| committer |  Borislav Petkov (AMD) <bp@alien8.de>
| 2023-08-07 20:43:59 +0200 |
| commit | 918a7a04e71745e99a0efc6753e587439b794b29 (patch) | |
| tree | cd0b8fa3ddff5187550cad22f24ddb3ffece8015 /arch/x86/boot | |
| parent | x86/decompressor: Call trampoline as a normal function (diff) | |
| download | linux-918a7a04e71745e99a0efc6753e587439b794b29.tar.gz linux-918a7a04e71745e99a0efc6753e587439b794b29.tar.bz2 linux-918a7a04e71745e99a0efc6753e587439b794b29.zip | |
x86/decompressor: Use standard calling convention for trampoline
Update the trampoline code so its arguments are passed via RDI and RSI,
which matches the ordinary SysV calling convention for x86_64. This will
allow this code to be called directly from C.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/r/20230807162720.545787-11-ardb@kernel.org
Diffstat (limited to 'arch/x86/boot')
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 27 | ||||
| -rw-r--r-- | arch/x86/boot/compressed/pgtable.h | 2 |
2 files changed, 14 insertions, 15 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 91b5eee30614..c47504208105 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -444,9 +444,9 @@ SYM_CODE_START(startup_64) movq %r15, %rdi call paging_prepare - /* Save the trampoline address in RCX */ - movq %rax, %rcx - + /* Pass the trampoline address and boolean flag as args #1 and #2 */ + movq %rax, %rdi + movq %rdx, %rsi leaq TRAMPOLINE_32BIT_CODE_OFFSET(%rax), %rax call *%rax @@ -531,11 +531,14 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) SYM_FUNC_END(.Lrelocated) /* - * This is the 32-bit trampoline that will be copied over to low memory. + * This is the 32-bit trampoline that will be copied over to low memory. It + * will be called using the ordinary 64-bit calling convention from code + * running in 64-bit mode. * * Return address is at the top of the stack (might be above 4G). - * ECX contains the base address of the trampoline memory. - * Non zero RDX means trampoline needs to enable 5-level paging. + * The first argument (EDI) contains the 32-bit addressable base of the + * trampoline memory. A non-zero second argument (ESI) means that the + * trampoline needs to enable 5-level paging. */ SYM_CODE_START(trampoline_32bit_src) /* @@ -582,7 +585,7 @@ SYM_CODE_START(trampoline_32bit_src) movl %eax, %cr0 /* Check what paging mode we want to be in after the trampoline */ - testl %edx, %edx + testl %esi, %esi jz 1f /* We want 5-level paging: don't touch CR3 if it already points to 5-level page tables */ @@ -597,21 +600,17 @@ SYM_CODE_START(trampoline_32bit_src) jz 3f 2: /* Point CR3 to the trampoline's new top level page table */ - leal TRAMPOLINE_32BIT_PGTABLE_OFFSET(%ecx), %eax + leal TRAMPOLINE_32BIT_PGTABLE_OFFSET(%edi), %eax movl %eax, %cr3 3: /* Set EFER.LME=1 as a precaution in case hypervsior pulls the rug */ - pushl %ecx - pushl %edx movl $MSR_EFER, %ecx rdmsr btsl $_EFER_LME, %eax /* Avoid writing EFER if no change was made (for TDX guest) */ jc 1f wrmsr -1: popl %edx - popl %ecx - +1: #ifdef CONFIG_X86_MCE /* * Preserve CR4.MCE if the kernel will enable #MC support. @@ -628,7 +627,7 @@ SYM_CODE_START(trampoline_32bit_src) /* Enable PAE and LA57 (if required) paging modes */ orl $X86_CR4_PAE, %eax - testl %edx, %edx + testl %esi, %esi jz 1f orl $X86_CR4_LA57, %eax 1: diff --git a/arch/x86/boot/compressed/pgtable.h b/arch/x86/boot/compressed/pgtable.h index 91dbb99203fb..4e8cef135226 100644 --- a/arch/x86/boot/compressed/pgtable.h +++ b/arch/x86/boot/compressed/pgtable.h @@ -14,7 +14,7 @@ extern unsigned long *trampoline_32bit; -extern void trampoline_32bit_src(void *return_ptr); +extern void trampoline_32bit_src(void *trampoline, bool enable_5lvl); #endif /* __ASSEMBLER__ */ #endif /* BOOT_COMPRESSED_PAGETABLE_H */ |