stackcollapse-record « bin « python « scripts « perf « tools - kernel - Hosts the 0x221E linux distro kernel.

Hosts the 0x221E linux distro kernel.

Ubuntu

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path: root/tools/perf/scripts/python/bin/stackcollapse-record

blob: 9d8f9f0f3a17c1e9c4042ce535e4853e64575b4e (plain)

#!/bin/sh

#
# stackcollapse.py can cover all type of perf samples including
# the tracepoints, so no special record requirements, just record what
# you want to analyze.
#
perf record "$@"

150. With [1], the loop unroll count is 600. The unroll count of 600 caused the program size close to 298k and this caused the following code is generated: 0: 7b 1a 00 ff 00 00 00 00 *(u64 *)(r10 - 256) = r1 ; uint64_t pid_tgid = bpf_get_current_pid_tgid(); 1: 85 00 00 00 0e 00 00 00 call 14 2: bf 06 00 00 00 00 00 00 r6 = r0 ; pid_t pid = (pid_t)(pid_tgid >> 32); 3: bf 61 00 00 00 00 00 00 r1 = r6 4: 77 01 00 00 20 00 00 00 r1 >>= 32 5: 63 1a fc ff 00 00 00 00 *(u32 *)(r10 - 4) = r1 6: bf a2 00 00 00 00 00 00 r2 = r10 7: 07 02 00 00 fc ff ff ff r2 += -4 ; PidData* pidData = bpf_map_lookup_elem(&pidmap, &pid); 8: 18 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r1 = 0 ll 10: 85 00 00 00 01 00 00 00 call 1 11: bf 08 00 00 00 00 00 00 r8 = r0 ; if (!pidData) 12: 15 08 15 e8 00 00 00 00 if r8 == 0 goto -6123 <LBB0_27588+0xffffffffffdae100> Note that insn 12 has a branch offset -6123 which is clearly illegal and will be rejected by the verifier. The negative offset is due to the branch range is greater than INT16_MAX. This patch changed the unroll count to be 150 to avoid above branch target insn out-of-range issue. Also the llvm is enhanced ([2]) to assert if the branch target insn is out of INT16 range. [1] https://reviews.llvm.org/D119148 [2] https://reviews.llvm.org/D123877 Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220419043230.2928530-1-yhs@fb.com