From: Ard Biesheuvel <ardb@kernel.org>
To: linux-efi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
Michael Roth <michael.roth@amd.com>
Subject: [PATCH v3 13/17] x86/compressed: move startup32_check_sev_cbit() into .text
Date: Tue, 22 Nov 2022 17:10:13 +0100 [thread overview]
Message-ID: <20221122161017.2426828-14-ardb@kernel.org> (raw)
In-Reply-To: <20221122161017.2426828-1-ardb@kernel.org>
Move startup32_check_sev_cbit() into the .text section and turn it into
an ordinary function using the ordinary 32-bit calling convention,
instead of saving/restoring the registers that are known to be live at
the only call site. This improves maintainability, and makes it possible
to move this function out of head_64.S and into a separate compilation
unit that is specific to memory encryption.
Note that this requires the call site to be moved before the mixed mode
check, as %eax will be live otherwise.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/x86/boot/compressed/head_64.S | 35 +++++++++++---------
1 file changed, 19 insertions(+), 16 deletions(-)
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 97b2167f128cbefe..272b2e97456f0dcf 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -259,6 +259,11 @@ SYM_FUNC_START(startup_32)
movl $__BOOT_TSS, %eax
ltr %ax
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+ /* Check if the C-bit position is correct when SEV is active */
+ call startup32_check_sev_cbit
+#endif
+
/*
* Setup for the jump to 64bit mode
*
@@ -276,8 +281,6 @@ SYM_FUNC_START(startup_32)
leal rva(startup_64_mixed_mode)(%ebp), %eax
1:
#endif
- /* Check if the C-bit position is correct when SEV is active */
- call startup32_check_sev_cbit
pushl $__KERNEL_CS
pushl %eax
@@ -732,16 +735,17 @@ SYM_DATA_END_LABEL(boot_idt, SYM_L_GLOBAL, boot_idt_end)
* 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
+ .text
+SYM_FUNC_START(startup32_check_sev_cbit)
pushl %ebx
- pushl %ecx
- pushl %edx
+ pushl %ebp
+
+ call 0f
+0: popl %ebp
/* Check for non-zero sev_status */
- movl rva(sev_status)(%ebp), %eax
+ movl (sev_status - 0b)(%ebp), %eax
testl %eax, %eax
jz 4f
@@ -756,17 +760,18 @@ SYM_FUNC_START(startup32_check_sev_cbit)
jnc 2b
/* Store to memory and keep it in the registers */
- movl %eax, rva(sev_check_data)(%ebp)
- movl %ebx, rva(sev_check_data+4)(%ebp)
+ leal (sev_check_data - 0b)(%ebp), %ebp
+ movl %eax, 0(%ebp)
+ movl %ebx, 4(%ebp)
/* Enable paging to see if encryption is active */
movl %cr0, %edx /* Backup %cr0 in %edx */
movl $(X86_CR0_PG | X86_CR0_PE), %ecx /* Enable Paging and Protected mode */
movl %ecx, %cr0
- cmpl %eax, rva(sev_check_data)(%ebp)
+ cmpl %eax, 0(%ebp)
jne 3f
- cmpl %ebx, rva(sev_check_data+4)(%ebp)
+ cmpl %ebx, 4(%ebp)
jne 3f
movl %edx, %cr0 /* Restore previous %cr0 */
@@ -778,13 +783,11 @@ SYM_FUNC_START(startup32_check_sev_cbit)
jmp 3b
4:
- popl %edx
- popl %ecx
+ popl %ebp
popl %ebx
- popl %eax
-#endif
RET
SYM_FUNC_END(startup32_check_sev_cbit)
+#endif
/*
* Stack and heap for uncompression
--
2.35.1
next prev parent reply other threads:[~2022-11-22 16:12 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-22 16:10 [PATCH v3 00/17] x86: head_64.S spring cleaning Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 01/17] x86/compressed: efi-mixed: rename efi_thunk_64.S to efi-mixed.S Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Rename " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 02/17] x86/compressed: efi-mixed: move 32-bit entrypoint code into .text section Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Move " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 03/17] x86/compressed: efi-mixed: move bootargs parsing out of 32-bit startup code Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Move " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 04/17] x86/compressed: efi-mixed: move efi32_pe_entry into .text section Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Move " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 05/17] x86/compressed: efi-mixed: move efi32_entry out of head_64.S Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Move " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 06/17] x86/compressed: efi-mixed: move efi32_pe_entry() " Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Move " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 07/17] x86/compressed: efi: merge multiple definitions of image_offset into one Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed, efi: Merge " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 08/17] x86/compressed: efi-mixed: simplify IDT/GDT preserve/restore Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Simplify IDT/GDT preserve/restore in the EFI thunk tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 09/17] x86/compressed: avoid touching ECX in startup32_set_idt_entry() Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Avoid " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 10/17] x86/compressed: pull global variable ref up into startup32_load_idt() Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Pull global variable reference " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 11/17] x86/compressed: move startup32_load_idt() into .text section Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Move " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 12/17] x86/compressed: move startup32_load_idt() out of head_64.S Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Move " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` Ard Biesheuvel [this message]
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Move startup32_check_sev_cbit() into .text tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 14/17] x86/compressed: move startup32_check_sev_cbit() out of head_64.S Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Move " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 15/17] x86/compressed: adhere to calling convention in get_sev_encryption_bit() Ard Biesheuvel
2022-11-24 8:12 ` [tip: x86/boot] x86/boot/compressed: Adhere " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 16/17] x86/compressed: only build mem_encrypt.S if AMD_MEM_ENCRYPT=y Ard Biesheuvel
2022-11-24 8:11 ` [tip: x86/boot] x86/boot/compressed: Only " tip-bot2 for Ard Biesheuvel
2022-11-22 16:10 ` [PATCH v3 17/17] efi: x86: Make the deprecated EFI handover protocol optional Ard Biesheuvel
2022-11-22 18:56 ` Randy Dunlap
2022-11-24 8:11 ` [tip: x86/boot] x86/efi: " tip-bot2 for Ard Biesheuvel
2022-11-22 20:48 ` [PATCH v3 00/17] x86: head_64.S spring cleaning Tom Lendacky
2022-11-22 21:37 ` Ard Biesheuvel
2022-11-22 21:42 ` Ard Biesheuvel
2022-11-22 21:50 ` Tom Lendacky
2022-11-22 21:51 ` Ard Biesheuvel
2022-11-22 21:49 ` Tom Lendacky
2022-11-22 22:20 ` Borislav Petkov
2022-11-23 10:49 ` Borislav Petkov
2022-11-23 10:52 ` Ard Biesheuvel
2022-11-23 11:09 ` Borislav Petkov
2022-11-23 11:22 ` Ard Biesheuvel
2022-11-23 14:16 ` Tom Lendacky
2022-11-23 14:33 ` Ard Biesheuvel
2022-11-23 14:13 ` Tom Lendacky
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