The following commit has been merged into the x86/asm branch of tip:
Commit-ID: f58b63857ae38b4484185b799a2759274b930c92
Gitweb: https://git.kernel.org/tip/f58b63857ae38b4484185b799a2759274b930c92
Author: Brian Gerst <brgerst@gmail.com>
AuthorDate: Thu, 23 Jan 2025 14:07:36 -05:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 18 Feb 2025 10:14:59 +01:00
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@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250123190747.745588-5-brgerst@gmail.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 4733a5f..723f181 100644
--- a/arch/x86/platform/pvh/head.S
+++ b/arch/x86/platform/pvh/head.S
@@ -173,10 +173,15 @@ SYM_CODE_START(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 the 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
/* Call xen_prepare_pvh() via the kernel virtual mapping */
@@ -238,8 +243,6 @@ 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)