kpatch: Handle __trace_check symbols as discardable#1490
Merged
joe-lawrence merged 1 commit intodynup:masterfrom Jan 19, 2026
Merged
kpatch: Handle __trace_check symbols as discardable#1490joe-lawrence merged 1 commit intodynup:masterfrom
joe-lawrence merged 1 commit intodynup:masterfrom
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Starting with kernel commit e30f8e61e251 ("tracing: Add a tracepoint
verification check at build time"), each defined and used tracepoint
adds its name to the __tracepoint_check section for build-time
verification. This section is discarded when linking vmlinux, so
symbols prefixed with __trace_check do not appear in vmlinux.symtab.
As a result, kpatch-build fails with: "couldn't find matching local
symbols in symbol table" for syscall.patch
i.e
readelf -p __tracepoint_check sys.o
String dump of section '__tracepoint_check':
[ 0] task_prctl_unknown
Disassembly of section __tracepoint_check:
0000000000000000 <__trace_check_task_prctl_unknown.1>:
0: 74 61 73 6b .long 0x7461736b
4: 5f 70 72 63 sl %r7,611(%r7)
8: 74 6c 5f 75 .long 0x746c5f75
c: 6e 6b 6e 6f aw %f6,3695(%r11,%r6)
10: 77 6e 00 00 .long 0x776e0000
To fix this, add symbols starting with __trace_check to
maybe_discarded_sym() so they are treated as discardable.
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
joe-lawrence
approved these changes
Jan 12, 2026
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Thanks, @sumanthkorikkar !
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Starting with kernel commit e30f8e61e251 ("tracing: Add a tracepoint verification check at build time"), each defined and used tracepoint adds its name to the __tracepoint_check section for build-time verification. This section is discarded when linking vmlinux, so symbols prefixed with __trace_check do not appear in vmlinux.symtab.
As a result, kpatch-build fails with: "couldn't find matching local symbols in symbol table" for syscall.patch
i.e
readelf -p __tracepoint_check sys.o
String dump of section '__tracepoint_check':
[ 0] task_prctl_unknown
Disassembly of section __tracepoint_check:
0000000000000000 <__trace_check_task_prctl_unknown.1>:
0: 74 61 73 6b .long 0x7461736b
4: 5f 70 72 63 sl %r7,611(%r7)
8: 74 6c 5f 75 .long 0x746c5f75
c: 6e 6b 6e 6f aw %f6,3695(%r11,%r6)
10: 77 6e 00 00 .long 0x776e0000
To fix this, add symbols starting with __trace_check to maybe_discarded_sym() so they are treated as discardable.