Messages in this thread Patch in this message |  | | From | Borislav Petkov <> | | Subject | [PATCH] x86/asm: Make sure verify_cpu() has a good stack | | Date | Thu, 31 Mar 2016 16:21:02 +0200 |
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From: Borislav Petkov <bp@suse.de>
04633df0c43d ("x86/cpu: Call verify_cpu() after having entered long mode too") added the call to verify_cpu() for sanitizing CPU configuration.
The latter uses the stack minimally and it can happen that we land in startup_64() directly from a 64-bit bootloader. Then we want to use our own, known good stack.
Do that.
APs don't need this as the trampoline sets up a stack for them.
Reported-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Mika Penttilä <mika.penttila@nextfour.com> --- arch/x86/kernel/head_64.S | 8 ++++++++ include/asm-generic/vmlinux.lds.h | 4 +++- 2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 22fbf9df61bb..e69742517a54 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -64,6 +64,14 @@ startup_64: * tables and then reload them. */ + /* + * Setup stack for verify_cpu(). "-8" because stack_start is defined + * this way, see below. Our best guess is a NULL ptr for stack + * termination heuristics and we don't want to break anything which + * might depend on it (kgdb, ...). + */ + leaq (__end_init_task - 8)(%rip), %rsp + /* Sanitize CPU configuration */ call verify_cpu diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 339125bb4d2c..6a67ab94b553 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -245,7 +245,9 @@ #define INIT_TASK_DATA(align) \ . = ALIGN(align); \ - *(.data..init_task) + VMLINUX_SYMBOL(__start_init_task) = .; \ + *(.data..init_task) \ + VMLINUX_SYMBOL(__end_init_task) = .; /* * Read only Data -- 2.7.3
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