diff mbox series

[bpf-next,v3,05/17] bpf: Support new signed div/mod instructions.

Message ID 20230720000129.104838-1-yhs@fb.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series bpf: Support new insns from cpu v4 | expand

Checks

Context Check Description
netdev/series_format fail Series longer than 15 patches (and no cover letter)
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1361 this patch: 1361
netdev/cc_maintainers warning 16 maintainers not CCed: tglx@linutronix.de hpa@zytor.com dsahern@kernel.org mingo@redhat.com kpsingh@kernel.org x86@kernel.org john.fastabend@gmail.com sdf@google.com netdev@vger.kernel.org martin.lau@linux.dev song@kernel.org dave.hansen@linux.intel.com davem@davemloft.net jolsa@kernel.org haoluo@google.com bp@alien8.de
netdev/build_clang success Errors and warnings before: 1365 this patch: 1365
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1384 this patch: 1384
netdev/checkpatch warning CHECK: No space is necessary after a cast WARNING: line length of 82 exceeds 80 columns WARNING: line length of 89 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-PR success PR summary
bpf/vmtest-bpf-next-VM_Test-1 success Logs for ${{ matrix.test }} on ${{ matrix.arch }} with ${{ matrix.toolchain_full }}
bpf/vmtest-bpf-next-VM_Test-2 success Logs for ShellCheck
bpf/vmtest-bpf-next-VM_Test-3 fail Logs for build for aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-4 fail Logs for build for s390x with gcc
bpf/vmtest-bpf-next-VM_Test-5 fail Logs for build for x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-6 fail Logs for build for x86_64 with llvm-16
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bpf/vmtest-bpf-next-VM_Test-8 success Logs for veristat

Commit Message

Yonghong Song July 20, 2023, 12:01 a.m. UTC 
Add interpreter/jit support for new signed div/mod insns.
The new signed div/mod instructions are encoded with
unsigned div/mod instructions plus insn->off == 1.
Also add basic verifier support to ensure new insns get
accepted.

Signed-off-by: Yonghong Song <yhs@fb.com>
---
 arch/x86/net/bpf_jit_comp.c |  27 ++++++---
 kernel/bpf/core.c           | 110 ++++++++++++++++++++++++++++++------
 kernel/bpf/verifier.c       |   6 +-
 3 files changed, 117 insertions(+), 26 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 4942a4c188b9..a89b62eb2b40 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1194,15 +1194,26 @@  static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image
 				/* mov rax, dst_reg */
 				emit_mov_reg(&prog, is64, BPF_REG_0, dst_reg);
 
-			/*
-			 * xor edx, edx
-			 * equivalent to 'xor rdx, rdx', but one byte less
-			 */
-			EMIT2(0x31, 0xd2);
+			if (insn->off == 0) {
+				/*
+				 * xor edx, edx
+				 * equivalent to 'xor rdx, rdx', but one byte less
+				 */
+				EMIT2(0x31, 0xd2);
 
-			/* div src_reg */
-			maybe_emit_1mod(&prog, src_reg, is64);
-			EMIT2(0xF7, add_1reg(0xF0, src_reg));
+				/* div src_reg */
+				maybe_emit_1mod(&prog, src_reg, is64);
+				EMIT2(0xF7, add_1reg(0xF0, src_reg));
+			} else {
+				if (BPF_CLASS(insn->code) == BPF_ALU)
+					EMIT1(0x99); /* cdq */
+				else
+					EMIT2(0x48, 0x99); /* cqo */
+
+				/* idiv src_reg */
+				maybe_emit_1mod(&prog, src_reg, is64);
+				EMIT2(0xF7, add_1reg(0xF8, src_reg));
+			}
 
 			if (BPF_OP(insn->code) == BPF_MOD &&
 			    dst_reg != BPF_REG_3)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index ad58697cec4b..3fe895199f6e 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1792,36 +1792,114 @@  static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn)
 		(*(s64 *) &DST) >>= IMM;
 		CONT;
 	ALU64_MOD_X:
-		div64_u64_rem(DST, SRC, &AX);
-		DST = AX;
+		switch (OFF) {
+		case 0:
+			div64_u64_rem(DST, SRC, &AX);
+			DST = AX;
+			break;
+		case 1:
+			AX = div64_s64(DST, SRC);
+			DST = DST - AX * SRC;
+			break;
+		}
 		CONT;
 	ALU_MOD_X:
-		AX = (u32) DST;
-		DST = do_div(AX, (u32) SRC);
+		switch (OFF) {
+		case 0:
+			AX = (u32) DST;
+			DST = do_div(AX, (u32) SRC);
+			break;
+		case 1:
+			AX = abs((s32)DST);
+			AX = do_div(AX, abs((s32)SRC));
+			if ((s32)DST < 0)
+				DST = (u32)-AX;
+			else
+				DST = (u32)AX;
+			break;
+		}
 		CONT;
 	ALU64_MOD_K:
-		div64_u64_rem(DST, IMM, &AX);
-		DST = AX;
+		switch (OFF) {
+		case 0:
+			div64_u64_rem(DST, IMM, &AX);
+			DST = AX;
+			break;
+		case 1:
+			AX = div64_s64(DST, IMM);
+			DST = DST - AX * IMM;
+			break;
+		}
 		CONT;
 	ALU_MOD_K:
-		AX = (u32) DST;
-		DST = do_div(AX, (u32) IMM);
+		switch (OFF) {
+		case 0:
+			AX = (u32) DST;
+			DST = do_div(AX, (u32) IMM);
+			break;
+		case 1:
+			AX = abs((s32)DST);
+			AX = do_div(AX, abs((s32)IMM));
+			if ((s32)DST < 0)
+				DST = (u32)-AX;
+			else
+				DST = (u32)AX;
+			break;
+		}
 		CONT;
 	ALU64_DIV_X:
-		DST = div64_u64(DST, SRC);
+		switch (OFF) {
+		case 0:
+			DST = div64_u64(DST, SRC);
+			break;
+		case 1:
+			DST = div64_s64(DST, SRC);
+			break;
+		}
 		CONT;
 	ALU_DIV_X:
-		AX = (u32) DST;
-		do_div(AX, (u32) SRC);
-		DST = (u32) AX;
+		switch (OFF) {
+		case 0:
+			AX = (u32) DST;
+			do_div(AX, (u32) SRC);
+			DST = (u32) AX;
+			break;
+		case 1:
+			AX = abs((s32)DST);
+			do_div(AX, abs((s32)SRC));
+			if ((s32)DST < 0 == (s32)SRC < 0)
+				DST = (u32)AX;
+			else
+				DST = (u32)-AX;
+			break;
+		}
 		CONT;
 	ALU64_DIV_K:
-		DST = div64_u64(DST, IMM);
+		switch (OFF) {
+		case 0:
+			DST = div64_u64(DST, IMM);
+			break;
+		case 1:
+			DST = div64_s64(DST, IMM);
+			break;
+		}
 		CONT;
 	ALU_DIV_K:
-		AX = (u32) DST;
-		do_div(AX, (u32) IMM);
-		DST = (u32) AX;
+		switch (OFF) {
+		case 0:
+			AX = (u32) DST;
+			do_div(AX, (u32) IMM);
+			DST = (u32) AX;
+			break;
+		case 1:
+			AX = abs((s32)DST);
+			do_div(AX, abs((s32)IMM));
+			if ((s32)DST < 0 == (s32)IMM < 0)
+				DST = (u32)AX;
+			else
+				DST = (u32)-AX;
+			break;
+		}
 		CONT;
 	ALU_END_TO_BE:
 		switch (IMM) {
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index b305f88c2569..9436fa795f39 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -13237,7 +13237,8 @@  static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
 	} else {	/* all other ALU ops: and, sub, xor, add, ... */
 
 		if (BPF_SRC(insn->code) == BPF_X) {
-			if (insn->imm != 0 || insn->off != 0) {
+			if (insn->imm != 0 || insn->off > 1 ||
+			    (insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) {
 				verbose(env, "BPF_ALU uses reserved fields\n");
 				return -EINVAL;
 			}
@@ -13246,7 +13247,8 @@  static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
 			if (err)
 				return err;
 		} else {
-			if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
+			if (insn->src_reg != BPF_REG_0 || insn->off > 1 ||
+			    (insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) {
 				verbose(env, "BPF_ALU uses reserved fields\n");
 				return -EINVAL;
 			}