Merge branch 'x86/pti' into x86/mm, to pick up dependencies

[linux-2.6-microblaze.git] / arch / x86 / include / asm / nospec-branch.h

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index b7063cf..d0dabea 100644 (file)
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -275,4 +275,41 @@ do {                                                                       \
 } while (0)
 
 #endif /* __ASSEMBLY__ */
+
+/*
+ * Below is used in the eBPF JIT compiler and emits the byte sequence
+ * for the following assembly:
+ *
+ * With retpolines configured:
+ *
+ *    callq do_rop
+ *  spec_trap:
+ *    pause
+ *    lfence
+ *    jmp spec_trap
+ *  do_rop:
+ *    mov %rax,(%rsp)
+ *    retq
+ *
+ * Without retpolines configured:
+ *
+ *    jmp *%rax
+ */
+#ifdef CONFIG_RETPOLINE
+# define RETPOLINE_RAX_BPF_JIT_SIZE    17
+# define RETPOLINE_RAX_BPF_JIT()                               \
+       EMIT1_off32(0xE8, 7);    /* callq do_rop */             \
+       /* spec_trap: */                                        \
+       EMIT2(0xF3, 0x90);       /* pause */                    \
+       EMIT3(0x0F, 0xAE, 0xE8); /* lfence */                   \
+       EMIT2(0xEB, 0xF9);       /* jmp spec_trap */            \
+       /* do_rop: */                                           \
+       EMIT4(0x48, 0x89, 0x04, 0x24); /* mov %rax,(%rsp) */    \
+       EMIT1(0xC3);             /* retq */
+#else
+# define RETPOLINE_RAX_BPF_JIT_SIZE    2
+# define RETPOLINE_RAX_BPF_JIT()                               \
+       EMIT2(0xFF, 0xE0);       /* jmp *%rax */
+#endif
+
 #endif /* _ASM_X86_NOSPEC_BRANCH_H_ */