powerpc64/bpf: jit support for sign extended load

Add jit support for sign extended load. Tested using test_bpf module.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240517075650.248801-4-asavkov@redhat.com

arch/powerpc/include/asm/ppc-opcode.h

@@ -471,6 +471,7 @@
 #define PPC_RAW_VCMPEQUB_RC(vrt, vra, vrb) \
 	(0x10000006 | ___PPC_RT(vrt) | ___PPC_RA(vra) | ___PPC_RB(vrb) | __PPC_RC21)
 #define PPC_RAW_LD(r, base, i)		(0xe8000000 | ___PPC_RT(r) | ___PPC_RA(base) | IMM_DS(i))
+#define PPC_RAW_LWA(r, base, i)		(0xe8000002 | ___PPC_RT(r) | ___PPC_RA(base) | IMM_DS(i))
 #define PPC_RAW_LWZ(r, base, i)		(0x80000000 | ___PPC_RT(r) | ___PPC_RA(base) | IMM_L(i))
 #define PPC_RAW_LWZX(t, a, b)		(0x7c00002e | ___PPC_RT(t) | ___PPC_RA(a) | ___PPC_RB(b))
 #define PPC_RAW_STD(r, base, i)		(0xf8000000 | ___PPC_RS(r) | ___PPC_RA(base) | IMM_DS(i))

arch/powerpc/net/bpf_jit_comp64.c

@@ -937,13 +937,19 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 		 */
 		/* dst = *(u8 *)(ul) (src + off) */
 		case BPF_LDX | BPF_MEM | BPF_B:
+		case BPF_LDX | BPF_MEMSX | BPF_B:
 		case BPF_LDX | BPF_PROBE_MEM | BPF_B:
+		case BPF_LDX | BPF_PROBE_MEMSX | BPF_B:
 		/* dst = *(u16 *)(ul) (src + off) */
 		case BPF_LDX | BPF_MEM | BPF_H:
+		case BPF_LDX | BPF_MEMSX | BPF_H:
 		case BPF_LDX | BPF_PROBE_MEM | BPF_H:
+		case BPF_LDX | BPF_PROBE_MEMSX | BPF_H:
 		/* dst = *(u32 *)(ul) (src + off) */
 		case BPF_LDX | BPF_MEM | BPF_W:
+		case BPF_LDX | BPF_MEMSX | BPF_W:
 		case BPF_LDX | BPF_PROBE_MEM | BPF_W:
+		case BPF_LDX | BPF_PROBE_MEMSX | BPF_W:
 		/* dst = *(u64 *)(ul) (src + off) */
 		case BPF_LDX | BPF_MEM | BPF_DW:
 		case BPF_LDX | BPF_PROBE_MEM | BPF_DW:
@@ -953,7 +959,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 			 * load only if addr is kernel address (see is_kernel_addr()), otherwise
 			 * set dst_reg=0 and move on.
 			 */
-			if (BPF_MODE(code) == BPF_PROBE_MEM) {
+			if (BPF_MODE(code) == BPF_PROBE_MEM || BPF_MODE(code) == BPF_PROBE_MEMSX) {
 				EMIT(PPC_RAW_ADDI(tmp1_reg, src_reg, off));
 				if (IS_ENABLED(CONFIG_PPC_BOOK3E_64))
 					PPC_LI64(tmp2_reg, 0x8000000000000000ul);
@@ -966,30 +972,47 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code
 				 * Check if 'off' is word aligned for BPF_DW, because
 				 * we might generate two instructions.
 				 */
-				if (BPF_SIZE(code) == BPF_DW && (off & 3))
+				if ((BPF_SIZE(code) == BPF_DW ||
+				    (BPF_SIZE(code) == BPF_B && BPF_MODE(code) == BPF_PROBE_MEMSX)) &&
+						(off & 3))
 					PPC_JMP((ctx->idx + 3) * 4);
 				else
 					PPC_JMP((ctx->idx + 2) * 4);
 			}
 
-			switch (size) {
-			case BPF_B:
-				EMIT(PPC_RAW_LBZ(dst_reg, src_reg, off));
-				break;
-			case BPF_H:
-				EMIT(PPC_RAW_LHZ(dst_reg, src_reg, off));
-				break;
-			case BPF_W:
-				EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off));
-				break;
-			case BPF_DW:
-				if (off % 4) {
-					EMIT(PPC_RAW_LI(tmp1_reg, off));
-					EMIT(PPC_RAW_LDX(dst_reg, src_reg, tmp1_reg));
-				} else {
-					EMIT(PPC_RAW_LD(dst_reg, src_reg, off));
+			if (BPF_MODE(code) == BPF_MEMSX || BPF_MODE(code) == BPF_PROBE_MEMSX) {
+				switch (size) {
+				case BPF_B:
+					EMIT(PPC_RAW_LBZ(dst_reg, src_reg, off));
+					EMIT(PPC_RAW_EXTSB(dst_reg, dst_reg));
+					break;
+				case BPF_H:
+					EMIT(PPC_RAW_LHA(dst_reg, src_reg, off));
+					break;
+				case BPF_W:
+					EMIT(PPC_RAW_LWA(dst_reg, src_reg, off));
+					break;
+				}
+			} else {
+				switch (size) {
+				case BPF_B:
+					EMIT(PPC_RAW_LBZ(dst_reg, src_reg, off));
+					break;
+				case BPF_H:
+					EMIT(PPC_RAW_LHZ(dst_reg, src_reg, off));
+					break;
+				case BPF_W:
+					EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off));
+					break;
+				case BPF_DW:
+					if (off % 4) {
+						EMIT(PPC_RAW_LI(tmp1_reg, off));
+						EMIT(PPC_RAW_LDX(dst_reg, src_reg, tmp1_reg));
+					} else {
+						EMIT(PPC_RAW_LD(dst_reg, src_reg, off));
+					}
+					break;
 				}
-				break;
 			}
 
 			if (size != BPF_DW && insn_is_zext(&insn[i + 1]))