diff mbox series

[bpf-next,03/10] s390/bpf: Introduce pre- and post- probe functions

Message ID 20240627090900.20017-4-iii@linux.ibm.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series s390/bpf: Implement arena | expand

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netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
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: 8 this patch: 8
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 12 maintainers not CCed: yonghong.song@linux.dev svens@linux.ibm.com haoluo@google.com linux-s390@vger.kernel.org jolsa@kernel.org song@kernel.org john.fastabend@gmail.com eddyz87@gmail.com kpsingh@kernel.org martin.lau@linux.dev sdf@google.com borntraeger@linux.ibm.com
netdev/build_clang success Errors and warnings before: 8 this patch: 8
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: 8 this patch: 8
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 133 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Ilya Leoshkevich June 27, 2024, 9:07 a.m. UTC 
Currently probe insns are handled by two "if" statements at the
beginning and at the end of bpf_jit_insn(). The first one needs to be
in sync with the huge insn->code statement that follows it, which was
not a problem so far, since the check is small.

The introduction of arena will make it significantly larger, and it
will no longer be obvious whether it is in sync with the opcode switch.

Move these statements to the new bpf_jit_probe_load_pre() and
bpf_jit_probe_post() functions, and call them only from cases that need
them.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 arch/s390/net/bpf_jit_comp.c | 58 +++++++++++++++++++++++++++---------
 1 file changed, 44 insertions(+), 14 deletions(-)
diff mbox series

Patch

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index d9d79aa2be1b..582fa3830772 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -704,14 +704,28 @@  static void bpf_jit_probe_emit_nop(struct bpf_jit *jit,
 	_EMIT2(0x0700);
 }
 
-static int bpf_jit_probe_mem(struct bpf_jit *jit, struct bpf_prog *fp,
-			     struct bpf_jit_probe *probe)
+static void bpf_jit_probe_load_pre(struct bpf_jit *jit, struct bpf_insn *insn,
+				   struct bpf_jit_probe *probe)
+{
+	if (BPF_MODE(insn->code) != BPF_PROBE_MEM &&
+	    BPF_MODE(insn->code) != BPF_PROBE_MEMSX)
+		return;
+
+	probe->prg = jit->prg;
+	probe->reg = reg2hex[insn->dst_reg];
+}
+
+static int bpf_jit_probe_post(struct bpf_jit *jit, struct bpf_prog *fp,
+			      struct bpf_jit_probe *probe)
 {
 	struct exception_table_entry *ex;
 	int i, prg;
 	s64 delta;
 	u8 *insn;
 
+	if (probe->prg == -1)
+		/* The probe is not armed. */
+		return 0;
 	bpf_jit_probe_emit_nop(jit, probe);
 	if (!fp->aux->extable)
 		/* Do nothing during early JIT passes. */
@@ -798,12 +812,6 @@  static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
 	int err;
 
 	bpf_jit_probe_init(&probe);
-	if (BPF_CLASS(insn->code) == BPF_LDX &&
-	    (BPF_MODE(insn->code) == BPF_PROBE_MEM ||
-	     BPF_MODE(insn->code) == BPF_PROBE_MEMSX)) {
-		probe.prg = jit->prg;
-		probe.reg = reg2hex[dst_reg];
-	}
 
 	switch (insn->code) {
 	/*
@@ -1497,51 +1505,79 @@  static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
 	 */
 	case BPF_LDX | BPF_MEM | BPF_B: /* dst = *(u8 *)(ul) (src + off) */
 	case BPF_LDX | BPF_PROBE_MEM | BPF_B:
+		bpf_jit_probe_load_pre(jit, insn, &probe);
 		/* llgc %dst,0(off,%src) */
 		EMIT6_DISP_LH(0xe3000000, 0x0090, dst_reg, src_reg, REG_0, off);
+		err = bpf_jit_probe_post(jit, fp, &probe);
+		if (err < 0)
+			return err;
 		jit->seen |= SEEN_MEM;
 		if (insn_is_zext(&insn[1]))
 			insn_count = 2;
 		break;
 	case BPF_LDX | BPF_MEMSX | BPF_B: /* dst = *(s8 *)(ul) (src + off) */
 	case BPF_LDX | BPF_PROBE_MEMSX | BPF_B:
+		bpf_jit_probe_load_pre(jit, insn, &probe);
 		/* lgb %dst,0(off,%src) */
 		EMIT6_DISP_LH(0xe3000000, 0x0077, dst_reg, src_reg, REG_0, off);
+		err = bpf_jit_probe_post(jit, fp, &probe);
+		if (err < 0)
+			return err;
 		jit->seen |= SEEN_MEM;
 		break;
 	case BPF_LDX | BPF_MEM | BPF_H: /* dst = *(u16 *)(ul) (src + off) */
 	case BPF_LDX | BPF_PROBE_MEM | BPF_H:
+		bpf_jit_probe_load_pre(jit, insn, &probe);
 		/* llgh %dst,0(off,%src) */
 		EMIT6_DISP_LH(0xe3000000, 0x0091, dst_reg, src_reg, REG_0, off);
+		err = bpf_jit_probe_post(jit, fp, &probe);
+		if (err < 0)
+			return err;
 		jit->seen |= SEEN_MEM;
 		if (insn_is_zext(&insn[1]))
 			insn_count = 2;
 		break;
 	case BPF_LDX | BPF_MEMSX | BPF_H: /* dst = *(s16 *)(ul) (src + off) */
 	case BPF_LDX | BPF_PROBE_MEMSX | BPF_H:
+		bpf_jit_probe_load_pre(jit, insn, &probe);
 		/* lgh %dst,0(off,%src) */
 		EMIT6_DISP_LH(0xe3000000, 0x0015, dst_reg, src_reg, REG_0, off);
+		err = bpf_jit_probe_post(jit, fp, &probe);
+		if (err < 0)
+			return err;
 		jit->seen |= SEEN_MEM;
 		break;
 	case BPF_LDX | BPF_MEM | BPF_W: /* dst = *(u32 *)(ul) (src + off) */
 	case BPF_LDX | BPF_PROBE_MEM | BPF_W:
+		bpf_jit_probe_load_pre(jit, insn, &probe);
 		/* llgf %dst,off(%src) */
 		jit->seen |= SEEN_MEM;
 		EMIT6_DISP_LH(0xe3000000, 0x0016, dst_reg, src_reg, REG_0, off);
+		err = bpf_jit_probe_post(jit, fp, &probe);
+		if (err < 0)
+			return err;
 		if (insn_is_zext(&insn[1]))
 			insn_count = 2;
 		break;
 	case BPF_LDX | BPF_MEMSX | BPF_W: /* dst = *(s32 *)(ul) (src + off) */
 	case BPF_LDX | BPF_PROBE_MEMSX | BPF_W:
+		bpf_jit_probe_load_pre(jit, insn, &probe);
 		/* lgf %dst,off(%src) */
 		jit->seen |= SEEN_MEM;
 		EMIT6_DISP_LH(0xe3000000, 0x0014, dst_reg, src_reg, REG_0, off);
+		err = bpf_jit_probe_post(jit, fp, &probe);
+		if (err < 0)
+			return err;
 		break;
 	case BPF_LDX | BPF_MEM | BPF_DW: /* dst = *(u64 *)(ul) (src + off) */
 	case BPF_LDX | BPF_PROBE_MEM | BPF_DW:
+		bpf_jit_probe_load_pre(jit, insn, &probe);
 		/* lg %dst,0(off,%src) */
 		jit->seen |= SEEN_MEM;
 		EMIT6_DISP_LH(0xe3000000, 0x0004, dst_reg, src_reg, REG_0, off);
+		err = bpf_jit_probe_post(jit, fp, &probe);
+		if (err < 0)
+			return err;
 		break;
 	/*
 	 * BPF_JMP / CALL
@@ -1906,12 +1942,6 @@  static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
 		return -1;
 	}
 
-	if (probe.prg != -1) {
-		err = bpf_jit_probe_mem(jit, fp, &probe);
-		if (err < 0)
-			return err;
-	}
-
 	return insn_count;
 }