| Message ID | 20220104014236.1512639-1-houtao1@huawei.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf] bpf, arm64: calculate offset as byte-offset for bpf line info | expand |
On 1/4/22 2:42 AM, Hou Tao wrote: > The bpf line info for arm64 is broken due to two reasons: > (1) insn_to_jit_off passed to bpf_prog_fill_jited_linfo() is > calculated in instruction granularity instead of bytes > granularity. > (2) insn_to_jit_off only considers the body itself and ignores > prologue before the body. > > So fix it by calculating offset as byte-offset and do build_prologue() > first in the first JIT pass. > > Fixes: 37ab566c178d ("bpf: arm64: Enable arm64 jit to provide bpf_line_info") > Signed-off-by: Hou Tao <houtao1@huawei.com> > --- > arch/arm64/net/bpf_jit_comp.c | 27 +++++++++++++++++---------- > 1 file changed, 17 insertions(+), 10 deletions(-) > > diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c > index 148ca51325bb..d7a6d4b523c9 100644 > --- a/arch/arm64/net/bpf_jit_comp.c > +++ b/arch/arm64/net/bpf_jit_comp.c > @@ -24,6 +24,8 @@ > > #include "bpf_jit.h" > > +#define INSN_SZ (sizeof(u32)) > + > #define TMP_REG_1 (MAX_BPF_JIT_REG + 0) > #define TMP_REG_2 (MAX_BPF_JIT_REG + 1) > #define TCALL_CNT (MAX_BPF_JIT_REG + 2) > @@ -154,10 +156,11 @@ static inline int bpf2a64_offset(int bpf_insn, int off, > bpf_insn++; > /* > * Whereas arm64 branch instructions encode the offset > - * from the branch itself, so we must subtract 1 from the > + * from the branch itself, so we must subtract 4 from the > * instruction offset. > */ > - return ctx->offset[bpf_insn + off] - (ctx->offset[bpf_insn] - 1); > + return (ctx->offset[bpf_insn + off] - > + (ctx->offset[bpf_insn] - INSN_SZ)) / INSN_SZ; > } > > static void jit_fill_hole(void *area, unsigned int size) > @@ -955,13 +958,14 @@ static int build_body(struct jit_ctx *ctx, bool extra_pass) > const struct bpf_insn *insn = &prog->insnsi[i]; > int ret; > > + /* BPF line info needs byte-offset instead of insn-offset */ > if (ctx->image == NULL) > - ctx->offset[i] = ctx->idx; > + ctx->offset[i] = ctx->idx * INSN_SZ; > ret = build_insn(insn, ctx, extra_pass); > if (ret > 0) { > i++; > if (ctx->image == NULL) > - ctx->offset[i] = ctx->idx; > + ctx->offset[i] = ctx->idx * INSN_SZ; > continue; > } > if (ret) > @@ -973,7 +977,7 @@ static int build_body(struct jit_ctx *ctx, bool extra_pass) > * instruction (end of program) > */ > if (ctx->image == NULL) > - ctx->offset[i] = ctx->idx; > + ctx->offset[i] = ctx->idx * INSN_SZ; > > return 0; > } > @@ -1058,15 +1062,18 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) > goto out_off; > } > > - /* 1. Initial fake pass to compute ctx->idx. */ > - > - /* Fake pass to fill in ctx->offset. */ > - if (build_body(&ctx, extra_pass)) { > + /* > + * 1. Initial fake pass to compute ctx->idx and ctx->offset. > + * > + * BPF line info needs ctx->offset[i] to be the byte offset > + * of instruction[i] in jited image, so build prologue first. > + */ > + if (build_prologue(&ctx, was_classic)) { > prog = orig_prog; > goto out_off; > } > > - if (build_prologue(&ctx, was_classic)) { > + if (build_body(&ctx, extra_pass)) { > prog = orig_prog; > goto out_off; Could you split this into two logical patches? Both 1/2 seem independent of each other and should have been rather 2 patches instead of 1. Did you check if also other JITs could be affected? Thanks, Daniel
Hi, On 1/7/2022 6:00 AM, Daniel Borkmann wrote: > On 1/4/22 2:42 AM, Hou Tao wrote: >> The bpf line info for arm64 is broken due to two reasons: >> (1) insn_to_jit_off passed to bpf_prog_fill_jited_linfo() is >> calculated in instruction granularity instead of bytes >> granularity. >> (2) insn_to_jit_off only considers the body itself and ignores >> prologue before the body. >> >> So fix it by calculating offset as byte-offset and do build_prologue() >> first in the first JIT pass. >> [snip] >> - /* Fake pass to fill in ctx->offset. */ >> - if (build_body(&ctx, extra_pass)) { >> + /* >> + * 1. Initial fake pass to compute ctx->idx and ctx->offset. >> + * >> + * BPF line info needs ctx->offset[i] to be the byte offset >> + * of instruction[i] in jited image, so build prologue first. >> + */ >> + if (build_prologue(&ctx, was_classic)) { >> prog = orig_prog; >> goto out_off; >> } >> - if (build_prologue(&ctx, was_classic)) { >> + if (build_body(&ctx, extra_pass)) { >> prog = orig_prog; >> goto out_off; > > Could you split this into two logical patches? Both 1/2 seem independent > of each other and should have been rather 2 patches instead of 1. > Sorry for the later reply. Splitting into two patches make sense for me. Will do it in v2. > Did you check if also other JITs could be affected? It seems sparc also doesn't represent offset by bytes and I can check other arches as well, but it is sad that I don't have the environments for these arches. > Thanks, > Daniel > .
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 148ca51325bb..d7a6d4b523c9 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -24,6 +24,8 @@ #include "bpf_jit.h" +#define INSN_SZ (sizeof(u32)) + #define TMP_REG_1 (MAX_BPF_JIT_REG + 0) #define TMP_REG_2 (MAX_BPF_JIT_REG + 1) #define TCALL_CNT (MAX_BPF_JIT_REG + 2) @@ -154,10 +156,11 @@ static inline int bpf2a64_offset(int bpf_insn, int off, bpf_insn++; /* * Whereas arm64 branch instructions encode the offset - * from the branch itself, so we must subtract 1 from the + * from the branch itself, so we must subtract 4 from the * instruction offset. */ - return ctx->offset[bpf_insn + off] - (ctx->offset[bpf_insn] - 1); + return (ctx->offset[bpf_insn + off] - + (ctx->offset[bpf_insn] - INSN_SZ)) / INSN_SZ; } static void jit_fill_hole(void *area, unsigned int size) @@ -955,13 +958,14 @@ static int build_body(struct jit_ctx *ctx, bool extra_pass) const struct bpf_insn *insn = &prog->insnsi[i]; int ret; + /* BPF line info needs byte-offset instead of insn-offset */ if (ctx->image == NULL) - ctx->offset[i] = ctx->idx; + ctx->offset[i] = ctx->idx * INSN_SZ; ret = build_insn(insn, ctx, extra_pass); if (ret > 0) { i++; if (ctx->image == NULL) - ctx->offset[i] = ctx->idx; + ctx->offset[i] = ctx->idx * INSN_SZ; continue; } if (ret) @@ -973,7 +977,7 @@ static int build_body(struct jit_ctx *ctx, bool extra_pass) * instruction (end of program) */ if (ctx->image == NULL) - ctx->offset[i] = ctx->idx; + ctx->offset[i] = ctx->idx * INSN_SZ; return 0; } @@ -1058,15 +1062,18 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) goto out_off; } - /* 1. Initial fake pass to compute ctx->idx. */ - - /* Fake pass to fill in ctx->offset. */ - if (build_body(&ctx, extra_pass)) { + /* + * 1. Initial fake pass to compute ctx->idx and ctx->offset. + * + * BPF line info needs ctx->offset[i] to be the byte offset + * of instruction[i] in jited image, so build prologue first. + */ + if (build_prologue(&ctx, was_classic)) { prog = orig_prog; goto out_off; } - if (build_prologue(&ctx, was_classic)) { + if (build_body(&ctx, extra_pass)) { prog = orig_prog; goto out_off; }
The bpf line info for arm64 is broken due to two reasons: (1) insn_to_jit_off passed to bpf_prog_fill_jited_linfo() is calculated in instruction granularity instead of bytes granularity. (2) insn_to_jit_off only considers the body itself and ignores prologue before the body. So fix it by calculating offset as byte-offset and do build_prologue() first in the first JIT pass. Fixes: 37ab566c178d ("bpf: arm64: Enable arm64 jit to provide bpf_line_info") Signed-off-by: Hou Tao <houtao1@huawei.com> --- arch/arm64/net/bpf_jit_comp.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-)