From: Ilya Leoshkevich <iii@linux.ibm.com>
To: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org, Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Ilya Leoshkevich <iii@linux.ibm.com>
Subject: [PATCH bpf-next 03/10] s390/bpf: Introduce pre- and post- probe functions
Date: Thu, 27 Jun 2024 11:07:06 +0200 [thread overview]
Message-ID: <20240627090900.20017-4-iii@linux.ibm.com> (raw)
In-Reply-To: <20240627090900.20017-1-iii@linux.ibm.com>
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 --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;
}
--
2.45.2
next prev parent reply other threads:[~2024-06-27 9:09 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-27 9:07 [PATCH bpf-next 00/10] s390/bpf: Implement arena Ilya Leoshkevich
2024-06-27 9:07 ` [PATCH bpf-next 01/10] s390/bpf: Factor out emitting probe nops Ilya Leoshkevich
2024-06-27 9:07 ` [PATCH bpf-next 02/10] s390/bpf: Get rid of get_probe_mem_regno() Ilya Leoshkevich
2024-06-27 9:07 ` Ilya Leoshkevich [this message]
2024-06-27 9:07 ` [PATCH bpf-next 04/10] s390/bpf: Land on the next JITed instruction after exception Ilya Leoshkevich
2024-06-27 9:07 ` [PATCH bpf-next 05/10] s390/bpf: Support BPF_PROBE_MEM32 Ilya Leoshkevich
2024-06-27 9:07 ` [PATCH bpf-next 06/10] s390/bpf: Support address space cast instruction Ilya Leoshkevich
2024-06-27 9:07 ` [PATCH bpf-next 07/10] s390/bpf: Enable arena Ilya Leoshkevich
2024-06-27 9:07 ` [PATCH bpf-next 08/10] s390/bpf: Support arena atomics Ilya Leoshkevich
2024-06-28 0:43 ` Alexei Starovoitov
2024-06-28 9:09 ` Ilya Leoshkevich
2024-06-27 9:07 ` [PATCH bpf-next 09/10] selftests/bpf: Add UAF tests for " Ilya Leoshkevich
2024-06-28 0:45 ` Alexei Starovoitov
2024-06-28 9:13 ` Ilya Leoshkevich
2024-07-03 2:10 ` kernel test robot
2024-06-27 9:07 ` [PATCH bpf-next 10/10] selftests/bpf: Remove arena tests from DENYLIST.s390x Ilya Leoshkevich
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