diff mbox series

[RFC,bpf-next,v2,08/16] MIPS: eBPF: support long jump for BPF_JMP|EXIT

Message ID 8f7207410035a7d2b1f5e0d87695880313f5adf6.1633392335.git.Tony.Ambardar@gmail.com (mailing list archive)
State RFC
Delegated to: BPF
Headers show
Series MIPS: eBPF: refactor code, add MIPS32 JIT | expand

Checks

Context Check Description
bpf/vmtest-bpf-next pending VM_Test
bpf/vmtest-bpf-next-PR pending PR summary
netdev/cover_letter success Series has a cover letter
netdev/fixes_present success Fixes tag not required for -next series
netdev/patch_count fail Series longer than 15 patches (and no cover letter)
netdev/tree_selection success Clearly marked for bpf-next
netdev/subject_prefix success Link
netdev/cc_maintainers fail 2 blamed authors not CCed: david.daney@cavium.com davem@davemloft.net; 2 maintainers not CCed: david.daney@cavium.com davem@davemloft.net
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 4 this patch: 4
netdev/verify_fixes success Fixes tag looks correct
netdev/checkpatch warning CHECK: From:/Signed-off-by: email comments mismatch: 'From: Tony Ambardar <tony.ambardar@gmail.com>' != 'Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>'
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success No static functions without inline keyword in header files

Commit Message

Tony Ambardar Oct. 5, 2021, 8:26 a.m. UTC 
Existing JIT code supports only short (18-bit) branches for BPF EXIT, and
results in some tests from module test_bpf not being jited. Update code
to fall back to long (28-bit) jumps if short branches are insufficient.

Before:
  test_bpf: #296 BPF_MAXINSNS: exec all MSH jited:0 1556004 PASS
  test_bpf: #297 BPF_MAXINSNS: ld_abs+get_processor_id jited:0 824957 PASS
  test_bpf: Summary: 378 PASSED, 0 FAILED, [364/366 JIT'ed]

After:
  test_bpf: #296 BPF_MAXINSNS: exec all MSH jited:1 221998 PASS
  test_bpf: #297 BPF_MAXINSNS: ld_abs+get_processor_id jited:1 490507 PASS
  test_bpf: Summary: 378 PASSED, 0 FAILED, [366/366 JIT'ed]

Fixes: b6bd53f9c4e8 ("MIPS: Add missing file for eBPF JIT.")
Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>
---
 arch/mips/net/ebpf_jit.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c
index 00dc20bc0def..7252cd44ff63 100644
--- a/arch/mips/net/ebpf_jit.c
+++ b/arch/mips/net/ebpf_jit.c
@@ -994,9 +994,14 @@  static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
 	case BPF_JMP | BPF_EXIT:
 		if (this_idx + 1 < exit_idx) {
 			b_off = b_imm(exit_idx, ctx);
-			if (is_bad_offset(b_off))
-				return -E2BIG;
-			emit_instr(ctx, beq, MIPS_R_ZERO, MIPS_R_ZERO, b_off);
+			if (is_bad_offset(b_off)) {
+				target = j_target(ctx, exit_idx);
+				if (target == (unsigned int)-1)
+					return -E2BIG;
+				emit_instr(ctx, j, target);
+			} else {
+				emit_instr(ctx, b, b_off);
+			}
 			emit_instr(ctx, nop);
 		}
 		break;