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-rw-r--r--arch/x86/lib/retpoline.S56
1 files changed, 0 insertions, 56 deletions
diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index 480edc3a5e03..c909961e678a 100644
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -7,7 +7,6 @@
#include <asm/alternative-asm.h>
#include <asm/export.h>
#include <asm/nospec-branch.h>
-#include <asm/bitsperlong.h>
.macro THUNK reg
.section .text.__x86.indirect_thunk
@@ -47,58 +46,3 @@ GENERATE_THUNK(r13)
GENERATE_THUNK(r14)
GENERATE_THUNK(r15)
#endif
-
-/*
- * Fill the CPU return stack buffer.
- *
- * Each entry in the RSB, if used for a speculative 'ret', contains an
- * infinite 'pause; lfence; jmp' loop to capture speculative execution.
- *
- * This is required in various cases for retpoline and IBRS-based
- * mitigations for the Spectre variant 2 vulnerability. Sometimes to
- * eliminate potentially bogus entries from the RSB, and sometimes
- * purely to ensure that it doesn't get empty, which on some CPUs would
- * allow predictions from other (unwanted!) sources to be used.
- *
- * Google experimented with loop-unrolling and this turned out to be
- * the optimal version - two calls, each with their own speculation
- * trap should their return address end up getting used, in a loop.
- */
-.macro STUFF_RSB nr:req sp:req
- mov $(\nr / 2), %_ASM_BX
- .align 16
-771:
- call 772f
-773: /* speculation trap */
- pause
- lfence
- jmp 773b
- .align 16
-772:
- call 774f
-775: /* speculation trap */
- pause
- lfence
- jmp 775b
- .align 16
-774:
- dec %_ASM_BX
- jnz 771b
- add $((BITS_PER_LONG/8) * \nr), \sp
-.endm
-
-#define RSB_FILL_LOOPS 16 /* To avoid underflow */
-
-ENTRY(__fill_rsb)
- STUFF_RSB RSB_FILL_LOOPS, %_ASM_SP
- ret
-END(__fill_rsb)
-EXPORT_SYMBOL_GPL(__fill_rsb)
-
-#define RSB_CLEAR_LOOPS 32 /* To forcibly overwrite all entries */
-
-ENTRY(__clear_rsb)
- STUFF_RSB RSB_CLEAR_LOOPS, %_ASM_SP
- ret
-END(__clear_rsb)
-EXPORT_SYMBOL_GPL(__clear_rsb)