diff options
| author | Ard Biesheuvel <ardb@kernel.org> | 2023-02-06 13:33:07 +0100 |
|---|---|---|
| committer | Ard Biesheuvel <ardb@kernel.org> | 2023-02-09 19:30:54 +0100 |
| commit | 93be2859e26c3be847780c65313da1b261833451 (patch) | |
| tree | 41b20e79a370172ee3630ab3039c5ffa90c73957 /arch/x86/kernel | |
| parent | 1d959312e2f23c8ee6ed9432a6fa4416b267477b (diff) | |
efi: x86: Wire up IBT annotation in memory attributes table
UEFI v2.10 extends the EFI memory attributes table with a flag that
indicates whether or not all RuntimeServicesCode regions were
constructed with ENDBR landing pads, permitting the OS to map these
regions with IBT restrictions enabled.
So let's take this into account on x86 as well.
Suggested-by: Peter Zijlstra <peterz@infradead.org> # ibt_save() changes
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/apm_32.c | 4 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 5 |
2 files changed, 5 insertions, 4 deletions
diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c index 60e330cdbd17..c6c15ce1952f 100644 --- a/arch/x86/kernel/apm_32.c +++ b/arch/x86/kernel/apm_32.c @@ -609,7 +609,7 @@ static long __apm_bios_call(void *_call) apm_irq_save(flags); firmware_restrict_branch_speculation_start(); - ibt = ibt_save(); + ibt = ibt_save(true); APM_DO_SAVE_SEGS; apm_bios_call_asm(call->func, call->ebx, call->ecx, &call->eax, &call->ebx, &call->ecx, &call->edx, @@ -690,7 +690,7 @@ static long __apm_bios_call_simple(void *_call) apm_irq_save(flags); firmware_restrict_branch_speculation_start(); - ibt = ibt_save(); + ibt = ibt_save(true); APM_DO_SAVE_SEGS; error = apm_bios_call_simple_asm(call->func, call->ebx, call->ecx, &call->eax); diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 9cfca3d7d0e2..54b246414eeb 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -571,13 +571,14 @@ __setup("nopku", setup_disable_pku); #ifdef CONFIG_X86_KERNEL_IBT -__noendbr u64 ibt_save(void) +__noendbr u64 ibt_save(bool disable) { u64 msr = 0; if (cpu_feature_enabled(X86_FEATURE_IBT)) { rdmsrl(MSR_IA32_S_CET, msr); - wrmsrl(MSR_IA32_S_CET, msr & ~CET_ENDBR_EN); + if (disable) + wrmsrl(MSR_IA32_S_CET, msr & ~CET_ENDBR_EN); } return msr; |