From: Ard Biesheuvel <ardb@kernel.org>
To: linux-efi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
Evgeniy Baskov <baskov@ispras.ru>, Borislav Petkov <bp@alien8.de>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Alexey Khoroshilov <khoroshilov@ispras.ru>,
Peter Jones <pjones@redhat.com>,
Gerd Hoffmann <kraxel@redhat.com>, Dave Young <dyoung@redhat.com>,
Mario Limonciello <mario.limonciello@amd.com>,
Kees Cook <keescook@chromium.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Joerg Roedel <jroedel@suse.de>
Subject: [PATCH v5 06/20] x86/decompressor: Store boot_params pointer in callee save register
Date: Wed, 7 Jun 2023 09:23:28 +0200 [thread overview]
Message-ID: <20230607072342.4054036-7-ardb@kernel.org> (raw)
In-Reply-To: <20230607072342.4054036-1-ardb@kernel.org>
Instead of pushing and popping %RSI several times to preserve the struct
boot_params pointer across the execution of the startup code, move it
into a callee save register before the first call into C, and copy it
back when needed.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/x86/boot/compressed/head_64.S | 34 +++++++-------------
1 file changed, 11 insertions(+), 23 deletions(-)
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 9f90661744741210..2d1b0ee94929f7ec 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -405,10 +405,14 @@ SYM_CODE_START(startup_64)
lretq
.Lon_kernel_cs:
+ /*
+ * RSI holds a pointer to a boot_params structure provided by the
+ * loader, and this needs to be preserved across C function calls. So
+ * move it into a callee saved register.
+ */
+ movq %rsi, %r15
- pushq %rsi
call load_stage1_idt
- popq %rsi
#ifdef CONFIG_AMD_MEM_ENCRYPT
/*
@@ -421,10 +425,8 @@ SYM_CODE_START(startup_64)
* detection/setup to ensure that has been done in advance of any dependent
* code.
*/
- pushq %rsi
- movq %rsi, %rdi /* real mode address */
+ movq %r15, %rdi /* pass struct boot_params pointer */
call sev_enable
- popq %rsi
#endif
/*
@@ -437,13 +439,9 @@ SYM_CODE_START(startup_64)
* - Non zero RDX means trampoline needs to enable 5-level
* paging.
*
- * RSI holds real mode data and needs to be preserved across
- * this function call.
*/
- pushq %rsi
- movq %rsi, %rdi /* real mode address */
+ movq %r15, %rdi /* pass struct boot_params pointer */
call paging_prepare
- popq %rsi
/* Save the trampoline address in RCX */
movq %rax, %rcx
@@ -468,14 +466,9 @@ trampoline_return:
*
* RDI is address of the page table to use instead of page table
* in trampoline memory (if required).
- *
- * RSI holds real mode data and needs to be preserved across
- * this function call.
*/
- pushq %rsi
leaq rva(top_pgtable)(%rbx), %rdi
call cleanup_trampoline
- popq %rsi
/* Zero EFLAGS */
pushq $0
@@ -485,7 +478,6 @@ trampoline_return:
* Copy the compressed kernel to the end of our buffer
* where decompression in place becomes safe.
*/
- pushq %rsi
leaq (_bss-8)(%rip), %rsi
leaq rva(_bss-8)(%rbx), %rdi
movl $(_bss - startup_32), %ecx
@@ -493,7 +485,6 @@ trampoline_return:
std
rep movsq
cld
- popq %rsi
/*
* The GDT may get overwritten either during the copy we just did or
@@ -525,30 +516,27 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
shrq $3, %rcx
rep stosq
- pushq %rsi
call load_stage2_idt
/* Pass boot_params to initialize_identity_maps() */
- movq (%rsp), %rdi
+ movq %r15, %rdi /* pass struct boot_params pointer */
call initialize_identity_maps
- popq %rsi
/*
* Do the extraction, and jump to the new kernel..
*/
- pushq %rsi /* Save the real mode argument */
- movq %rsi, %rdi /* real mode address */
+ movq %r15, %rdi /* pass struct boot_params pointer */
leaq boot_heap(%rip), %rsi /* malloc area for uncompression */
leaq input_data(%rip), %rdx /* input_data */
movl input_len(%rip), %ecx /* input_len */
movq %rbp, %r8 /* output target address */
movl output_len(%rip), %r9d /* decompressed length, end of relocs */
call extract_kernel /* returns kernel entry point in %rax */
- popq %rsi
/*
* Jump to the decompressed kernel.
*/
+ movq %r15, %rsi
jmp *%rax
SYM_FUNC_END(.Lrelocated)
--
2.39.2
next prev parent reply other threads:[~2023-06-07 7:27 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-07 7:23 [PATCH v5 00/20] efi/x86: Avoid bare metal decompressor during EFI boot Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 01/20] x86/efistub: Branch straight to kernel entry point from C code Ard Biesheuvel
2023-06-07 18:53 ` Borislav Petkov
2023-06-07 19:39 ` Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 02/20] x86/efistub: Simplify and clean up handover entry code Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 03/20] x86/decompressor: Avoid magic offsets for EFI handover entrypoint Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 04/20] x86/efistub: Clear BSS in EFI handover protocol entrypoint Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 05/20] x86/decompressor: Use proper sequence to take the address of the GOT Ard Biesheuvel
2023-06-21 11:08 ` Borislav Petkov
2023-06-23 14:00 ` Ard Biesheuvel
2023-07-07 13:56 ` Borislav Petkov
2023-06-07 7:23 ` Ard Biesheuvel [this message]
2023-07-10 9:06 ` [PATCH v5 06/20] x86/decompressor: Store boot_params pointer in callee save register Borislav Petkov
2023-07-10 21:55 ` Ard Biesheuvel
2023-07-11 7:57 ` Borislav Petkov
2023-06-07 7:23 ` [PATCH v5 07/20] x86/decompressor: Call trampoline as a normal function Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 08/20] x86/decompressor: Use standard calling convention for trampoline Ard Biesheuvel
2023-06-07 19:38 ` Yunhong Jiang
2023-06-07 20:07 ` Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 09/20] x86/decompressor: Avoid the need for a stack in the 32-bit trampoline Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 10/20] x86/decompressor: Call trampoline directly from C code Ard Biesheuvel
2023-06-07 18:09 ` Yunhong Jiang
2023-06-08 8:04 ` Ard Biesheuvel
2023-06-08 18:15 ` Yunhong Jiang
2023-06-07 7:23 ` [PATCH v5 11/20] x86/decompressor: Only call the trampoline when changing paging levels Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 12/20] x86/decompressor: Merge trampoline cleanup with switching code Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 13/20] x86/efistub: Perform 4/5 level paging switch from the stub Ard Biesheuvel
2023-06-07 20:19 ` Yunhong Jiang
2023-06-07 20:31 ` Ard Biesheuvel
2023-06-08 0:43 ` Yunhong Jiang
2023-06-08 6:34 ` Ard Biesheuvel
2023-06-08 16:10 ` Yunhong Jiang
2023-06-07 7:23 ` [PATCH v5 14/20] x86/efistub: Prefer EFI memory attributes protocol over DXE services Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 15/20] decompress: Use 8 byte alignment Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 16/20] x86/decompressor: Move global symbol references to C code Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 17/20] x86/decompressor: Factor out kernel decompression and relocation Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 18/20] efi/libstub: Add limit argument to efi_random_alloc() Ard Biesheuvel
2023-06-07 7:23 ` [PATCH v5 19/20] x86/efistub: Perform SNP feature test while running in the firmware Ard Biesheuvel
2023-06-07 16:07 ` Tom Lendacky
2023-06-07 16:51 ` Ard Biesheuvel
2023-06-07 17:29 ` Tom Lendacky
2023-06-07 7:23 ` [PATCH v5 20/20] x86/efistub: Avoid legacy decompressor when doing EFI boot Ard Biesheuvel
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