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Message-ID: <20241105155801.1779119-6-brgerst@gmail.com>
Date: Tue, 5 Nov 2024 10:57:50 -0500
From: Brian Gerst <brgerst@...il.com>
To: linux-kernel@...r.kernel.org,
x86@...nel.org
Cc: Ingo Molnar <mingo@...nel.org>,
"H . Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>,
Ard Biesheuvel <ardb@...nel.org>,
Uros Bizjak <ubizjak@...il.com>,
Brian Gerst <brgerst@...il.com>
Subject: [PATCH v5 05/16] x86/pvh: Use fixed_percpu_data for early boot GSBASE
Instead of having a private area for the stack canary, use
fixed_percpu_data for GSBASE like the native kernel.
Signed-off-by: Brian Gerst <brgerst@...il.com>
---
arch/x86/platform/pvh/head.S | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/arch/x86/platform/pvh/head.S b/arch/x86/platform/pvh/head.S
index 64fca49cd88f..b0a9a58952aa 100644
--- a/arch/x86/platform/pvh/head.S
+++ b/arch/x86/platform/pvh/head.S
@@ -159,10 +159,15 @@ SYM_CODE_START_LOCAL(pvh_start_xen)
1:
UNWIND_HINT_END_OF_STACK
- /* Set base address in stack canary descriptor. */
- mov $MSR_GS_BASE,%ecx
- leal canary(%rip), %eax
- xor %edx, %edx
+ /*
+ * Set up GSBASE.
+ * Note that, on SMP, the boot cpu uses init data section until
+ * the per cpu areas are set up.
+ */
+ movl $MSR_GS_BASE,%ecx
+ leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx
+ movq %edx, %eax
+ shrq $32, %rdx
wrmsr
/*
@@ -232,8 +237,6 @@ SYM_DATA_START_LOCAL(gdt_start)
SYM_DATA_END_LABEL(gdt_start, SYM_L_LOCAL, gdt_end)
.balign 16
-SYM_DATA_LOCAL(canary, .fill 48, 1, 0)
-
SYM_DATA_START_LOCAL(early_stack)
.fill BOOT_STACK_SIZE, 1, 0
SYM_DATA_END_LABEL(early_stack, SYM_L_LOCAL, early_stack_end)
--
2.47.0
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