Paul Burton wrote 11.12.2019 02:23:
Hi Paul,
On Mon, Dec 09, 2019 at 07:52:52PM +0100, Paul Chaignon wrote:
All BPF JIT compilers except RISC-V's and MIPS' enforce a 33-tail
calls
limit at runtime. In addition, a test was recently added, in
tailcalls2,
to check this limit.
This patch updates the tail call limit in MIPS' JIT compiler to allow
33 tail calls.
Hi Paul,
You've restored MIPS cBPF in mips-fixes tree, doesn't it require any
changes to limit tail calls to 33? This series includes only eBPF as
there was no MIPS cBPF at the moment of writing.
Fixes: b6bd53f9c4e8 ("MIPS: Add missing file for eBPF JIT.")
Reported-by: Mahshid Khezri <khezri.mahshid@xxxxxxxxx>
Signed-off-by: Paul Chaignon <paul.chaignon@xxxxxxxxxx>
I'd be happy to take this through mips-fixes, but equally happy for it
to go through the BPF/net trees in which case:
Acked-by: Paul Burton <paulburton@xxxxxxxxxx>
Thanks,
Paul
---
arch/mips/net/ebpf_jit.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c
index 46b76751f3a5..3ec69d9cbe88 100644
--- a/arch/mips/net/ebpf_jit.c
+++ b/arch/mips/net/ebpf_jit.c
@@ -604,6 +604,7 @@ static void emit_const_to_reg(struct jit_ctx *ctx,
int dst, u64 value)
static int emit_bpf_tail_call(struct jit_ctx *ctx, int this_idx)
{
int off, b_off;
+ int tcc_reg;
ctx->flags |= EBPF_SEEN_TC;
/*
@@ -616,14 +617,14 @@ static int emit_bpf_tail_call(struct jit_ctx
*ctx, int this_idx)
b_off = b_imm(this_idx + 1, ctx);
emit_instr(ctx, bne, MIPS_R_AT, MIPS_R_ZERO, b_off);
/*
- * if (--TCC < 0)
+ * if (TCC-- < 0)
* goto out;
*/
/* Delay slot */
- emit_instr(ctx, daddiu, MIPS_R_T5,
- (ctx->flags & EBPF_TCC_IN_V1) ? MIPS_R_V1 : MIPS_R_S4, -1);
+ tcc_reg = (ctx->flags & EBPF_TCC_IN_V1) ? MIPS_R_V1 : MIPS_R_S4;
+ emit_instr(ctx, daddiu, MIPS_R_T5, tcc_reg, -1);
b_off = b_imm(this_idx + 1, ctx);
- emit_instr(ctx, bltz, MIPS_R_T5, b_off);
+ emit_instr(ctx, bltz, tcc_reg, b_off);
/*
* prog = array->ptrs[index];
* if (prog == NULL)
--
2.17.1
Regards,
ᚷ ᛖ ᚢ ᚦ ᚠ ᚱ
