diff options
Diffstat (limited to 'arch/x86/entry/entry.S')
| -rw-r--r-- | arch/x86/entry/entry.S | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S index d9feadffa972..175958b02f2b 100644 --- a/arch/x86/entry/entry.S +++ b/arch/x86/entry/entry.S @@ -5,24 +5,32 @@ #include <linux/export.h> #include <linux/linkage.h> +#include <linux/objtool.h> #include <asm/msr-index.h> #include <asm/unwind_hints.h> #include <asm/segment.h> #include <asm/cache.h> +#include <asm/cpufeatures.h> +#include <asm/nospec-branch.h> #include "calling.h" .pushsection .noinstr.text, "ax" -SYM_FUNC_START(entry_ibpb) +/* Clobbers AX, CX, DX */ +SYM_FUNC_START(write_ibpb) + ANNOTATE_NOENDBR movl $MSR_IA32_PRED_CMD, %ecx - movl $PRED_CMD_IBPB, %eax + movl _ASM_RIP(x86_pred_cmd), %eax xorl %edx, %edx wrmsr + + /* Make sure IBPB clears return stack preductions too. */ + FILL_RETURN_BUFFER %rax, RSB_CLEAR_LOOPS, X86_BUG_IBPB_NO_RET RET -SYM_FUNC_END(entry_ibpb) +SYM_FUNC_END(write_ibpb) /* For KVM */ -EXPORT_SYMBOL_GPL(entry_ibpb); +EXPORT_SYMBOL_GPL(write_ibpb); .popsection @@ -46,3 +54,17 @@ EXPORT_SYMBOL_GPL(mds_verw_sel); .popsection THUNK warn_thunk_thunk, __warn_thunk + +/* + * Clang's implementation of TLS stack cookies requires the variable in + * question to be a TLS variable. If the variable happens to be defined as an + * ordinary variable with external linkage in the same compilation unit (which + * amounts to the whole of vmlinux with LTO enabled), Clang will drop the + * segment register prefix from the references, resulting in broken code. Work + * around this by avoiding the symbol used in -mstack-protector-guard-symbol= + * entirely in the C code, and use an alias emitted by the linker script + * instead. + */ +#if defined(CONFIG_STACKPROTECTOR) && defined(CONFIG_SMP) +EXPORT_SYMBOL(__ref_stack_chk_guard); +#endif |