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| author |   Alexei Starovoitov <ast@kernel.org> | 2024-03-05 19:19:28 -0800 |
|---|---|---|
| committer |   Andrii Nakryiko <andrii@kernel.org> | 2024-03-06 15:18:04 -0800 |
| commit | 06375801525717173aee790310b7d959bb77879b (patch) | |
| tree | 56f571c37744c55fbab9eb4952875c1725e968e7 /tools/testing | |
| parent | bpf: Recognize that two registers are safe when their ranges match (diff) | |
| download | wireguard-linux-06375801525717173aee790310b7d959bb77879b.tar.xz wireguard-linux-06375801525717173aee790310b7d959bb77879b.zip | |
bpf: Add cond_break macro
Use may_goto instruction to implement cond_break macro.
Ideally the macro should be written as:
asm volatile goto(".byte 0xe5;
.byte 0;
.short %l[l_break] ...
.long 0;
but LLVM doesn't recognize fixup of 2 byte PC relative yet.
Hence use
asm volatile goto(".byte 0xe5;
.byte 0;
.long %l[l_break] ...
.short 0;
that produces correct asm on little endian.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Tested-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240306031929.42666-4-alexei.starovoitov@gmail.com
Diffstat (limited to 'tools/testing')
| -rw-r--r-- | tools/testing/selftests/bpf/bpf_experimental.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h index 0d749006d107..bc9a0832ae72 100644 --- a/tools/testing/selftests/bpf/bpf_experimental.h +++ b/tools/testing/selftests/bpf/bpf_experimental.h @@ -326,6 +326,18 @@ l_true: \ }) #endif +#define cond_break \ + ({ __label__ l_break, l_continue; \ + asm volatile goto("1:.byte 0xe5; \ + .byte 0; \ + .long ((%l[l_break] - 1b - 8) / 8) & 0xffff; \ + .short 0" \ + :::: l_break); \ + goto l_continue; \ + l_break: break; \ + l_continue:; \ + }) + #ifndef bpf_nop_mov #define bpf_nop_mov(var) \ asm volatile("%[reg]=%[reg]"::[reg]"r"((short)var)) |