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authorLinus Torvalds2022-03-27 10:17:23 -0700
committerLinus Torvalds2022-03-27 10:17:23 -0700
commit7001052160d172f6de06adeffde24dde9935ece8 (patch)
tree65fbc9c0df5a2989b68882ce1d893a0d78134c6a /arch/x86/kvm
parentf022814633e1c600507b3a99691b4d624c2813f0 (diff)
parent3986f65d4f408ce9d0a361e3226a3246a5fb701c (diff)
Merge tag 'x86_core_for_5.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 CET-IBT (Control-Flow-Integrity) support from Peter Zijlstra: "Add support for Intel CET-IBT, available since Tigerlake (11th gen), which is a coarse grained, hardware based, forward edge Control-Flow-Integrity mechanism where any indirect CALL/JMP must target an ENDBR instruction or suffer #CP. Additionally, since Alderlake (12th gen)/Sapphire-Rapids, speculation is limited to 2 instructions (and typically fewer) on branch targets not starting with ENDBR. CET-IBT also limits speculation of the next sequential instruction after the indirect CALL/JMP [1]. CET-IBT is fundamentally incompatible with retpolines, but provides, as described above, speculation limits itself" [1] https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/branch-history-injection.html * tag 'x86_core_for_5.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits) kvm/emulate: Fix SETcc emulation for ENDBR x86/Kconfig: Only allow CONFIG_X86_KERNEL_IBT with ld.lld >= 14.0.0 x86/Kconfig: Only enable CONFIG_CC_HAS_IBT for clang >= 14.0.0 kbuild: Fixup the IBT kbuild changes x86/Kconfig: Do not allow CONFIG_X86_X32_ABI=y with llvm-objcopy x86: Remove toolchain check for X32 ABI capability x86/alternative: Use .ibt_endbr_seal to seal indirect calls objtool: Find unused ENDBR instructions objtool: Validate IBT assumptions objtool: Add IBT/ENDBR decoding objtool: Read the NOENDBR annotation x86: Annotate idtentry_df() x86,objtool: Move the ASM_REACHABLE annotation to objtool.h x86: Annotate call_on_stack() objtool: Rework ASM_REACHABLE x86: Mark __invalid_creds() __noreturn exit: Mark do_group_exit() __noreturn x86: Mark stop_this_cpu() __noreturn objtool: Ignore extra-symbol code objtool: Rename --duplicate to --lto ...
Diffstat (limited to 'arch/x86/kvm')
-rw-r--r--arch/x86/kvm/emulate.c16
1 files changed, 10 insertions, 6 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 7ba4ec77feeb..f9c00c89829b 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -24,6 +24,7 @@
#include <linux/stringify.h>
#include <asm/debugreg.h>
#include <asm/nospec-branch.h>
+#include <asm/ibt.h>
#include "x86.h"
#include "tss.h"
@@ -189,7 +190,7 @@
#define X16(x...) X8(x), X8(x)
#define NR_FASTOP (ilog2(sizeof(ulong)) + 1)
-#define FASTOP_SIZE 8
+#define FASTOP_SIZE (8 * (1 + HAS_KERNEL_IBT))
struct opcode {
u64 flags;
@@ -311,7 +312,8 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop);
#define __FOP_FUNC(name) \
".align " __stringify(FASTOP_SIZE) " \n\t" \
".type " name ", @function \n\t" \
- name ":\n\t"
+ name ":\n\t" \
+ ASM_ENDBR
#define FOP_FUNC(name) \
__FOP_FUNC(#name)
@@ -433,21 +435,23 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop);
/*
* Depending on .config the SETcc functions look like:
*
+ * ENDBR [4 bytes; CONFIG_X86_KERNEL_IBT]
* SETcc %al [3 bytes]
* RET [1 byte]
* INT3 [1 byte; CONFIG_SLS]
*
- * Which gives possible sizes 4 or 5. When rounded up to the
- * next power-of-two alignment they become 4 or 8.
+ * Which gives possible sizes 4, 5, 8 or 9. When rounded up to the
+ * next power-of-two alignment they become 4, 8 or 16 resp.
*/
-#define SETCC_LENGTH (4 + IS_ENABLED(CONFIG_SLS))
-#define SETCC_ALIGN (4 << IS_ENABLED(CONFIG_SLS))
+#define SETCC_LENGTH (ENDBR_INSN_SIZE + 4 + IS_ENABLED(CONFIG_SLS))
+#define SETCC_ALIGN (4 << IS_ENABLED(CONFIG_SLS) << HAS_KERNEL_IBT)
static_assert(SETCC_LENGTH <= SETCC_ALIGN);
#define FOP_SETCC(op) \
".align " __stringify(SETCC_ALIGN) " \n\t" \
".type " #op ", @function \n\t" \
#op ": \n\t" \
+ ASM_ENDBR \
#op " %al \n\t" \
__FOP_RET(#op)