Re: [PATCH v3 3/8] bpf powerpc: refactor JIT compiler code
From: Christophe Leroy <hidden>
Date: 2021-09-21 14:02:53
Also in:
bpf, netdev
Le 21/09/2021 à 15:29, Hari Bathini a écrit :
quoted hunk ↗ jump to hunk
Refactor powerpc LDX JITing code to simplify adding BPF_PROBE_MEM support. Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> --- Changes in v3: * Dropped ST(X) JITing coderefactoring and ensured the changes are minimal and relevant to BPF_PROBE_MEM support. * Added a default for size switch case to ensure compiler would not complain. arch/powerpc/net/bpf_jit_comp32.c | 42 ++++++++++++++++++++----------- arch/powerpc/net/bpf_jit_comp64.c | 40 +++++++++++++++++++---------- 2 files changed, 55 insertions(+), 27 deletions(-)diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c index b60b59426a24..6e4956cd52e7 100644 --- a/arch/powerpc/net/bpf_jit_comp32.c +++ b/arch/powerpc/net/bpf_jit_comp32.c@@ -282,6 +282,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * u32 src_reg = bpf_to_ppc(ctx, insn[i].src_reg); u32 src_reg_h = src_reg - 1; u32 tmp_reg = bpf_to_ppc(ctx, TMP_REG); + u32 size = BPF_SIZE(code); s16 off = insn[i].off; s32 imm = insn[i].imm; bool func_addr_fixed;@@ -810,23 +811,36 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * * BPF_LDX */ case BPF_LDX | BPF_MEM | BPF_B: /* dst = *(u8 *)(ul) (src + off) */ - EMIT(PPC_RAW_LBZ(dst_reg, src_reg, off)); - if (!fp->aux->verifier_zext) - EMIT(PPC_RAW_LI(dst_reg_h, 0)); - break; + fallthrough; case BPF_LDX | BPF_MEM | BPF_H: /* dst = *(u16 *)(ul) (src + off) */ - EMIT(PPC_RAW_LHZ(dst_reg, src_reg, off)); - if (!fp->aux->verifier_zext) - EMIT(PPC_RAW_LI(dst_reg_h, 0)); - break; + fallthrough; case BPF_LDX | BPF_MEM | BPF_W: /* dst = *(u32 *)(ul) (src + off) */ - EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off)); - if (!fp->aux->verifier_zext) - EMIT(PPC_RAW_LI(dst_reg_h, 0)); - break; + fallthrough; case BPF_LDX | BPF_MEM | BPF_DW: /* dst = *(u64 *)(ul) (src + off) */ - EMIT(PPC_RAW_LWZ(dst_reg_h, src_reg, off)); - EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off + 4)); + switch (size) { + case BPF_B: + EMIT(PPC_RAW_LBZ(dst_reg, src_reg, off)); + break; + case BPF_H: + EMIT(PPC_RAW_LHZ(dst_reg, src_reg, off)); + break; + case BPF_W: + EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off)); + break; + case BPF_DW: + EMIT(PPC_RAW_LWZ(dst_reg_h, src_reg, off)); + EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off + 4)); + break; + /* + * With size not being an enum and BPF_B/H/W/DW being macros, ensure no + * compiler warning/error by adding a default case that never reaches. + */
Thinking about it once more, in fact this is already bounded by the upper switch/case, so there is no possibility to end up here with something else than the 4 cases and that's probably the reason why GCC says nothing about it, so I now think that a default is unnecessary and should not be added. Sorry for that.
quoted hunk ↗ jump to hunk
+ default: + break; + } + + if (size != BPF_DW && !fp->aux->verifier_zext) + EMIT(PPC_RAW_LI(dst_reg_h, 0)); break; /*diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 2a87da50d9a4..991eb43d4cd2 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c@@ -285,6 +285,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * u32 code = insn[i].code; u32 dst_reg = b2p[insn[i].dst_reg]; u32 src_reg = b2p[insn[i].src_reg]; + u32 size = BPF_SIZE(code); s16 off = insn[i].off; s32 imm = insn[i].imm; bool func_addr_fixed;@@ -716,25 +717,38 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * */ /* dst = *(u8 *)(ul) (src + off) */ case BPF_LDX | BPF_MEM | BPF_B: - EMIT(PPC_RAW_LBZ(dst_reg, src_reg, off)); - if (insn_is_zext(&insn[i + 1])) - addrs[++i] = ctx->idx * 4; - break; + fallthrough; /* dst = *(u16 *)(ul) (src + off) */ case BPF_LDX | BPF_MEM | BPF_H: - EMIT(PPC_RAW_LHZ(dst_reg, src_reg, off)); - if (insn_is_zext(&insn[i + 1])) - addrs[++i] = ctx->idx * 4; - break; + fallthrough; /* dst = *(u32 *)(ul) (src + off) */ case BPF_LDX | BPF_MEM | BPF_W: - EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off)); - if (insn_is_zext(&insn[i + 1])) - addrs[++i] = ctx->idx * 4; - break; + fallthrough; /* dst = *(u64 *)(ul) (src + off) */ case BPF_LDX | BPF_MEM | BPF_DW: - PPC_BPF_LL(dst_reg, src_reg, off); + switch (size) { + case BPF_B: + EMIT(PPC_RAW_LBZ(dst_reg, src_reg, off)); + break; + case BPF_H: + EMIT(PPC_RAW_LHZ(dst_reg, src_reg, off)); + break; + case BPF_W: + EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off)); + break; + case BPF_DW: + PPC_BPF_LL(dst_reg, src_reg, off); + break; + /* + * With size not being an enum and BPF_B/H/W/DW being macros, ensure no + * compiler warning/error by adding a default case that never reaches. + */
Same
+ default: + break; + } + + if (size != BPF_DW && insn_is_zext(&insn[i + 1])) + addrs[++i] = ctx->idx * 4; break; /*