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| author | Anton Protopopov <a.s.protopopov@gmail.com> | 2025-11-05 09:04:08 +0000 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2025-11-05 17:53:23 -0800 |
| commit | dd3fd3c965595a3ae8f4d70df6c42931b2fdfd24 (patch) | |
| tree | cef12658c2706131973437bb2d9b2cd889fa25d0 /tools/lib/bpf/libbpf_internal.h | |
| parent | bc414d35831bffae725b249c8650669ed100e5f7 (diff) | |
libbpf: support llvm-generated indirect jumps
For v4 instruction set LLVM is allowed to generate indirect jumps for
switch statements and for 'goto *rX' assembly. Every such a jump will
be accompanied by necessary metadata, e.g. (`llvm-objdump -Sr ...`):
0: r2 = 0x0 ll
0000000000000030: R_BPF_64_64 BPF.JT.0.0
Here BPF.JT.1.0 is a symbol residing in the .jumptables section:
Symbol table:
4: 0000000000000000 240 OBJECT GLOBAL DEFAULT 4 BPF.JT.0.0
The -bpf-min-jump-table-entries llvm option may be used to control the
minimal size of a switch which will be converted to an indirect jumps.
Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251105090410.1250500-11-a.s.protopopov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools/lib/bpf/libbpf_internal.h')
| -rw-r--r-- | tools/lib/bpf/libbpf_internal.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 35b2527bedec..fc59b21b51b5 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -74,6 +74,8 @@ #define ELF64_ST_VISIBILITY(o) ((o) & 0x03) #endif +#define JUMPTABLES_SEC ".jumptables" + #define BTF_INFO_ENC(kind, kind_flag, vlen) \ ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN)) #define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type) |