From: Ard Biesheuvel <ardb+git@google.com>
To: linux-kernel@vger.kernel.org
Cc: x86@kernel.org, Ard Biesheuvel <ardb@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Eric Biederman <ebiederm@xmission.com>,
kexec@lists.infradead.org, Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Kees Cook <keescook@chromium.org>,
Bill Wendling <morbo@google.com>,
Justin Stitt <justinstitt@google.com>,
Masahiro Yamada <masahiroy@kernel.org>
Subject: [RFC PATCH 8/9] x86/purgatory: Simplify references to regs array
Date: Wed, 24 Apr 2024 17:53:18 +0200 [thread overview]
Message-ID: <20240424155309.1719454-19-ardb+git@google.com> (raw)
In-Reply-To: <20240424155309.1719454-11-ardb+git@google.com>
From: Ard Biesheuvel <ardb@kernel.org>
Use a single symbol reference and offset addressing to load the contents
of the register file from memory, instead of using a symbol reference
for each, which results in larger code and more ELF overhead. While at
it, rename the individual labels with an .L prefix so they are omitted
from the ELF symbol table.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/x86/purgatory/entry64.S | 67 ++++++++++----------
1 file changed, 34 insertions(+), 33 deletions(-)
diff --git a/arch/x86/purgatory/entry64.S b/arch/x86/purgatory/entry64.S
index 3d09781d4f9a..56487fb7fa1d 100644
--- a/arch/x86/purgatory/entry64.S
+++ b/arch/x86/purgatory/entry64.S
@@ -37,45 +37,46 @@ SYM_CODE_START(entry64)
new_cs_exit:
/* Load the registers */
- movq rax(%rip), %rax
- movq rbx(%rip), %rbx
- movq rcx(%rip), %rcx
- movq rdx(%rip), %rdx
- movq rsi(%rip), %rsi
- movq rdi(%rip), %rdi
- movq rbp(%rip), %rbp
- movq r8(%rip), %r8
- movq r9(%rip), %r9
- movq r10(%rip), %r10
- movq r11(%rip), %r11
- movq r12(%rip), %r12
- movq r13(%rip), %r13
- movq r14(%rip), %r14
- movq r15(%rip), %r15
+ leaq entry64_regs(%rip), %r15
+ movq 0x00(%r15), %rax
+ movq 0x08(%r15), %rcx
+ movq 0x10(%r15), %rdx
+ movq 0x18(%r15), %rbx
+ movq 0x20(%r15), %rbp
+ movq 0x28(%r15), %rsi
+ movq 0x30(%r15), %rdi
+ movq 0x38(%r15), %r8
+ movq 0x40(%r15), %r9
+ movq 0x48(%r15), %r10
+ movq 0x50(%r15), %r11
+ movq 0x58(%r15), %r12
+ movq 0x60(%r15), %r13
+ movq 0x68(%r15), %r14
+ movq 0x70(%r15), %r15
/* Jump to the new code... */
- jmpq *rip(%rip)
+ jmpq *.Lrip(%rip)
SYM_CODE_END(entry64)
.section ".rodata"
- .balign 4
+ .balign 8
SYM_DATA_START(entry64_regs)
-rax: .quad 0x0
-rcx: .quad 0x0
-rdx: .quad 0x0
-rbx: .quad 0x0
-rbp: .quad 0x0
-rsi: .quad 0x0
-rdi: .quad 0x0
-r8: .quad 0x0
-r9: .quad 0x0
-r10: .quad 0x0
-r11: .quad 0x0
-r12: .quad 0x0
-r13: .quad 0x0
-r14: .quad 0x0
-r15: .quad 0x0
-rip: .quad 0x0
+.Lrax: .quad 0x0
+.Lrcx: .quad 0x0
+.Lrdx: .quad 0x0
+.Lrbx: .quad 0x0
+.Lrbp: .quad 0x0
+.Lrsi: .quad 0x0
+.Lrdi: .quad 0x0
+.Lr8: .quad 0x0
+.Lr9: .quad 0x0
+.Lr10: .quad 0x0
+.Lr11: .quad 0x0
+.Lr12: .quad 0x0
+.Lr13: .quad 0x0
+.Lr14: .quad 0x0
+.Lr15: .quad 0x0
+.Lrip: .quad 0x0
SYM_DATA_END(entry64_regs)
/* GDT */
--
2.44.0.769.g3c40516874-goog
next prev parent reply other threads:[~2024-04-24 15:53 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-24 15:53 [RFC PATCH 0/9] kexec x86 purgatory cleanup Ard Biesheuvel
2024-04-24 15:53 ` [RFC PATCH 1/9] x86/purgatory: Drop function entry padding from purgatory Ard Biesheuvel
2024-04-24 15:53 ` [RFC PATCH 2/9] x86/purgatory: Simplify stack handling Ard Biesheuvel
2024-04-24 18:26 ` Nathan Chancellor
2024-04-26 21:32 ` Justin Stitt
2024-04-26 21:53 ` Nathan Chancellor
2024-04-26 22:01 ` Justin Stitt
2024-04-24 15:53 ` [RFC PATCH 3/9] x86/purgatory: Drop pointless GDT switch Ard Biesheuvel
2024-04-24 15:53 ` [RFC PATCH 4/9] x86/purgatory: Avoid absolute reference to GDT Ard Biesheuvel
2024-04-24 17:38 ` Brian Gerst
2024-04-24 17:53 ` Ard Biesheuvel
2024-04-24 19:00 ` Brian Gerst
2024-04-24 15:53 ` [RFC PATCH 5/9] x86/purgatory: Simplify GDT and drop data segment Ard Biesheuvel
2024-04-24 15:53 ` [RFC PATCH 6/9] kexec: Add support for fully linked purgatory executables Ard Biesheuvel
2024-04-24 15:53 ` [RFC PATCH 7/9] x86/purgatory: Use fully linked PIE ELF executable Ard Biesheuvel
2024-04-24 15:53 ` Ard Biesheuvel [this message]
2024-04-24 15:53 ` [RFC PATCH 9/9] kexec: Drop support for partially linked purgatory executables Ard Biesheuvel
2024-04-24 20:04 ` [RFC PATCH 0/9] kexec x86 purgatory cleanup Eric W. Biederman
2024-04-24 20:52 ` Ard Biesheuvel
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