Files
linux/kernel/bpf
Eduard Zingerman 2c167d9177 bpf: change logging scheme for live stack analysis
Instead of breadcrumbs like:

  (d2,cs15) frame 0 insn 18 +live -16
  (d2,cs15) frame 0 insn 17 +live -16

Print final accumulated stack use/def data per-func_instance
per-instruction. printed func_instance's are ordered by callsite and
depth. For example:

  stack use/def subprog#0 shared_instance_must_write_overwrite (d0,cs0):
    0: (b7) r1 = 1
    1: (7b) *(u64 *)(r10 -8) = r1        ; def: fp0-8
    2: (7b) *(u64 *)(r10 -16) = r1       ; def: fp0-16
    3: (bf) r1 = r10
    4: (07) r1 += -8
    5: (bf) r2 = r10
    6: (07) r2 += -16
    7: (85) call pc+7                    ; use: fp0-8 fp0-16
    8: (bf) r1 = r10
    9: (07) r1 += -16
   10: (bf) r2 = r10
   11: (07) r2 += -8
   12: (85) call pc+2                    ; use: fp0-8 fp0-16
   13: (b7) r0 = 0
   14: (95) exit
  stack use/def subprog#1 forwarding_rw (d1,cs7):
   15: (85) call pc+1                    ; use: fp0-8 fp0-16
   16: (95) exit
  stack use/def subprog#1 forwarding_rw (d1,cs12):
   15: (85) call pc+1                    ; use: fp0-8 fp0-16
   16: (95) exit
  stack use/def subprog#2 write_first_read_second (d2,cs15):
   17: (7a) *(u64 *)(r1 +0) = 42
   18: (79) r0 = *(u64 *)(r2 +0)         ; use: fp0-8 fp0-16
   19: (95) exit

For groups of three or more consecutive stack slots, abbreviate as
follows:

   25: (85) call bpf_loop#181            ; use: fp2-8..-512 fp1-8..-512 fp0-8..-512

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260410-patch-set-v4-10-5d4eecb343db@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-04-10 15:13:37 -07:00
..
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