The upcoming arena support for the loop-based BPF_XCHG implementation
requires emitting nop and extable entries separately. Move nop handling
into a separate function, and keep track of the nop offset.
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
---
arch/s390/net/bpf_jit_comp.c | 62 +++++++++++++++++++++++-------------
1 file changed, 40 insertions(+), 22 deletions(-)
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 4be8f5cadd02..260e7009784b 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -693,24 +693,52 @@ bool ex_handler_bpf(const struct exception_table_entry *x, struct pt_regs *regs)
return true;
}
+/*
+ * A single BPF probe instruction
+ */
+struct bpf_jit_probe {
+ int prg; /* JITed instruction offset */
+ int nop_prg; /* JITed nop offset */
+};
+
+static void bpf_jit_probe_init(struct bpf_jit_probe *probe)
+{
+ probe->prg = -1;
+ probe->nop_prg = -1;
+}
+
+/*
+ * Handlers of certain exceptions leave psw.addr pointing to the instruction
+ * directly after the failing one. Therefore, create two exception table
+ * entries and also add a nop in case two probing instructions come directly
+ * after each other.
+ */
+static void bpf_jit_probe_emit_nop(struct bpf_jit *jit,
+ struct bpf_jit_probe *probe)
+{
+ probe->nop_prg = jit->prg;
+ /* bcr 0,%0 */
+ _EMIT2(0x0700);
+}
+
static int bpf_jit_probe_mem(struct bpf_jit *jit, struct bpf_prog *fp,
- int probe_prg, int nop_prg)
+ struct bpf_jit_probe *probe)
{
struct exception_table_entry *ex;
- int reg, prg;
+ int i, prg, reg;
s64 delta;
u8 *insn;
- int i;
+ bpf_jit_probe_emit_nop(jit, probe);
if (!fp->aux->extable)
/* Do nothing during early JIT passes. */
return 0;
- insn = jit->prg_buf + probe_prg;
+ insn = jit->prg_buf + probe->prg;
reg = get_probe_mem_regno(insn);
if (WARN_ON_ONCE(reg < 0))
/* JIT bug - unexpected probe instruction. */
return -1;
- if (WARN_ON_ONCE(probe_prg + insn_length(*insn) != nop_prg))
+ if (WARN_ON_ONCE(probe->prg + insn_length(*insn) != probe->nop_prg))
/* JIT bug - gap between probe and nop instructions. */
return -1;
for (i = 0; i < 2; i++) {
@@ -719,7 +747,7 @@ static int bpf_jit_probe_mem(struct bpf_jit *jit, struct bpf_prog *fp,
return -1;
ex = &fp->aux->extable[jit->excnt];
/* Add extable entries for probe and nop instructions. */
- prg = i == 0 ? probe_prg : nop_prg;
+ prg = i == 0 ? probe->prg : probe->nop_prg;
delta = jit->prg_buf + prg - (u8 *)&ex->insn;
if (WARN_ON_ONCE(delta < INT_MIN || delta > INT_MAX))
/* JIT bug - code and extable must be close. */
@@ -729,7 +757,7 @@ static int bpf_jit_probe_mem(struct bpf_jit *jit, struct bpf_prog *fp,
* Always land on the nop. Note that extable infrastructure
* ignores fixup field, it is handled by ex_handler_bpf().
*/
- delta = jit->prg_buf + nop_prg - (u8 *)&ex->fixup;
+ delta = jit->prg_buf + probe->nop_prg - (u8 *)&ex->fixup;
if (WARN_ON_ONCE(delta < INT_MIN || delta > INT_MAX))
/* JIT bug - landing pad and extable must be close. */
return -1;
@@ -782,19 +810,19 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
s32 branch_oc_off = insn->off;
u32 dst_reg = insn->dst_reg;
u32 src_reg = insn->src_reg;
+ struct bpf_jit_probe probe;
int last, insn_count = 1;
u32 *addrs = jit->addrs;
s32 imm = insn->imm;
s16 off = insn->off;
- int probe_prg = -1;
unsigned int mask;
- int nop_prg;
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.prg = jit->prg;
switch (insn->code) {
/*
@@ -1897,18 +1925,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
return -1;
}
- if (probe_prg != -1) {
- /*
- * Handlers of certain exceptions leave psw.addr pointing to
- * the instruction directly after the failing one. Therefore,
- * create two exception table entries and also add a nop in
- * case two probing instructions come directly after each
- * other.
- */
- nop_prg = jit->prg;
- /* bcr 0,%0 */
- _EMIT2(0x0700);
- err = bpf_jit_probe_mem(jit, fp, probe_prg, nop_prg);
+ if (probe.prg != -1) {
+ err = bpf_jit_probe_mem(jit, fp, &probe);
if (err < 0)
return err;
}
--
2.45.2
