From 55caa653014d50a3e10b5dbc282c641cfce5c9f2 Mon Sep 17 00:00:00 2001 From: Joe Lawrence Date: Fri, 26 Jun 2026 17:21:40 -0400 Subject: [PATCH] perf symbols: skip livepatch symbols in kcore_copy kallsyms processing Livepatch symbols (.klp.sym.*) carry a [module] tag but resolve to core kernel text addresses. When kcore_copy__process_kallsyms() encounters these symbols, they are treated as module symbols, pulling the first_module_symbol down to a kernel text address. This corrupts the module memory range used to build the kcore PT_LOAD segments. For example, with a kpatch module containing a ".klp.sym.vmlinux.arch_release_task_struct,0" livepatch symbol loaded: kernel symbols ... ffffffffb4a41120 arch_release_task_struct ... ^ ... | aliased by .klp.sym ... | drags first_module_symbol here | (43M gap) | bloated kcore segment | module symbols | ffffffffc047b000 <-- correct first_module_symbol ... ... This causes the module PT_LOAD segment to start at the .klp.sym address and not the real first module address, bloating the kcore copy: Baseline (no livepatch): VirtAddr ffffffffc047b000, 8.5M Bloated (with livepatch): VirtAddr ffffffffb4a41000, 54M Post-fix (with livepatch): VirtAddr ffffffffc047b000, 8.9M Filter livepatch symbols early in kcore_copy__process_kallsyms() before they can affect module boundary tracking. Reported-by: Sashiko Link: https://sashiko.dev/#/patchset/20260624201254.472576-1-joe.lawrence@redhat.com?part=1 Signed-off-by: Joe Lawrence Acked-by: Petr Mladek Signed-off-by: Namhyung Kim --- tools/perf/util/symbol-elf.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index 39562bdec8b9..f6f6b54da131 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -2216,6 +2216,10 @@ static int kcore_copy__process_kallsyms(void *arg, const char *name, char type, if (!kallsyms__is_function(type)) return 0; + /* Ignore livepatch symbols */ + if (is_livepatch_symbol(name)) + return 0; + if (strchr(name, '[')) { if (!kci->first_module_symbol || start < kci->first_module_symbol) kci->first_module_symbol = start;