1 files changed, 61 insertions, 2 deletions

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 78a19c93b380..dd2bcf0e7d00 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -25,6 +25,8 @@
 #include <linux/bpf.h>
 #include <asm/cacheflush.h>
 #include <asm/dis.h>
+#include <asm/facility.h>
+#include <asm/nospec-branch.h>
 #include <asm/set_memory.h>
 #include "bpf_jit.h"
 
@@ -41,6 +43,8 @@ struct bpf_jit {
 	int base_ip;		/* Base address for literal pool */
 	int ret0_ip;		/* Address of return 0 */
 	int exit_ip;		/* Address of exit */
+	int r1_thunk_ip;	/* Address of expoline thunk for 'br %r1' */
+	int r14_thunk_ip;	/* Address of expoline thunk for 'br %r14' */
 	int tail_call_start;	/* Tail call start offset */
 	int labels[1];		/* Labels for local jumps */
 };
@@ -250,6 +254,19 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
 	REG_SET_SEEN(b2);					\
 })
 
+#define EMIT6_PCREL_RILB(op, b, target)				\
+({								\
+	int rel = (target - jit->prg) / 2;			\
+	_EMIT6(op | reg_high(b) << 16 | rel >> 16, rel & 0xffff);	\
+	REG_SET_SEEN(b);					\
+})
+
+#define EMIT6_PCREL_RIL(op, target)				\
+({								\
+	int rel = (target - jit->prg) / 2;			\
+	_EMIT6(op | rel >> 16, rel & 0xffff);			\
+})
+
 #define _EMIT6_IMM(op, imm)					\
 ({								\
 	unsigned int __imm = (imm);				\
@@ -469,8 +486,45 @@ static void bpf_jit_epilogue(struct bpf_jit *jit, u32 stack_depth)
 	EMIT4(0xb9040000, REG_2, BPF_REG_0);
 	/* Restore registers */
 	save_restore_regs(jit, REGS_RESTORE, stack_depth);
+	if (IS_ENABLED(CC_USING_EXPOLINE) && !nospec_disable) {
+		jit->r14_thunk_ip = jit->prg;
+		/* Generate __s390_indirect_jump_r14 thunk */
+		if (test_facility(35)) {
+			/* exrl %r0,.+10 */
+			EMIT6_PCREL_RIL(0xc6000000, jit->prg + 10);
+		} else {
+			/* larl %r1,.+14 */
+			EMIT6_PCREL_RILB(0xc0000000, REG_1, jit->prg + 14);
+			/* ex 0,0(%r1) */
+			EMIT4_DISP(0x44000000, REG_0, REG_1, 0);
+		}
+		/* j . */
+		EMIT4_PCREL(0xa7f40000, 0);
+	}
 	/* br %r14 */
 	_EMIT2(0x07fe);
+
+	if (IS_ENABLED(CC_USING_EXPOLINE) && !nospec_disable &&
+	    (jit->seen & SEEN_FUNC)) {
+		jit->r1_thunk_ip = jit->prg;
+		/* Generate __s390_indirect_jump_r1 thunk */
+		if (test_facility(35)) {
+			/* exrl %r0,.+10 */
+			EMIT6_PCREL_RIL(0xc6000000, jit->prg + 10);
+			/* j . */
+			EMIT4_PCREL(0xa7f40000, 0);
+			/* br %r1 */
+			_EMIT2(0x07f1);
+		} else {
+			/* larl %r1,.+14 */
+			EMIT6_PCREL_RILB(0xc0000000, REG_1, jit->prg + 14);
+			/* ex 0,S390_lowcore.br_r1_tampoline */
+			EMIT4_DISP(0x44000000, REG_0, REG_0,
+				   offsetof(struct lowcore, br_r1_trampoline));
+			/* j . */
+			EMIT4_PCREL(0xa7f40000, 0);
+		}
+	}
 }
 
 /*
@@ -966,8 +1020,13 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
 		/* lg %w1,<d(imm)>(%l) */
 		EMIT6_DISP_LH(0xe3000000, 0x0004, REG_W1, REG_0, REG_L,
 			      EMIT_CONST_U64(func));
-		/* basr %r14,%w1 */
-		EMIT2(0x0d00, REG_14, REG_W1);
+		if (IS_ENABLED(CC_USING_EXPOLINE) && !nospec_disable) {
+			/* brasl %r14,__s390_indirect_jump_r1 */
+			EMIT6_PCREL_RILB(0xc0050000, REG_14, jit->r1_thunk_ip);
+		} else {
+			/* basr %r14,%w1 */
+			EMIT2(0x0d00, REG_14, REG_W1);
+		}
 		/* lgr %b0,%r2: load return value into %b0 */
 		EMIT4(0xb9040000, BPF_REG_0, REG_2);
 		if ((jit->seen & SEEN_SKB) &&