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| author | Puranjay Mohan <puranjay@kernel.org> | 2026-08-07 11:16:29 -0700 |
|---|---|---|
| committer | Josh Poimboeuf <jpoimboe@kernel.org> | 2026-08-12 13:33:32 -0700 |
| commit | 6656cf1e975aa152c082012b820efffaebd49979 (patch) | |
| tree | 1f0220f7a0f5571ec62d678e6e087874e226d4ba /tools/objtool | |
| parent | 51c1de13486315ad46a74b40ec17124916a08277 (diff) | |
objtool/klp: Fix vmlinux .klp.symid link error for .exitcall.exit symbols
Building a kernel via klp-build fails to link:
`__exitcall_aes_mod_exit' referenced in section `.klp.symid' of vmlinux.o: defined in discarded section `.exitcall.exit' of vmlinux.o
`__exitcall_dax_exit' referenced in section `.klp.symid' of vmlinux.o: defined in discarded section `.exitcall.exit' of vmlinux.o
`__exitcall_hid_exit' referenced in section `.klp.symid' of vmlinux.o: defined in discarded section `.exitcall.exit' of vmlinux.o
`__exitcall_usb_serial_module_exit' referenced in section `.klp.symid' of vmlinux.o: defined in discarded section `.exitcall.exit' of vmlinux.o
module_exit() on a built-in emits a static __exitcall_$fn pointer into
.exitcall.exit, which vmlinux.lds.h discards unconditionally via
EXIT_CALL. When two built-in translation units define a module_exit()
function of the same name, the resulting local symbols collide,
symid_needed() sees a duplicate and emits a .klp.symid entry for each,
referencing symbols the linker then throws away.
Same-named module_exit() functions are not rare:
dax_exit drivers/dax/device.c, drivers/dax/fsdev.c
hid_exit drivers/hid/hid-core.c, drivers/hid/usbhid/hid-core.c
aes_mod_exit arch/arm64/crypto/aes-ce-ccm-glue.c, lib/crypto/aes.c
usb_serial_module_exit module_usb_serial_driver() expands to this fixed
name in each of its ~49 users
The last one makes the collision structural rather than accidental: any
kernel with two built-in USB serial drivers has it. This is not arch
specific either; it only requires the objects to be built in rather than
modular, which is why a monolithic config trips it while a typical
distro config does not.
Add .exitcall.exit to the discarded section list so its symbols don't get
symids.
This is the same failure mode as "objtool/klp: Fix vmlinux .klp.symid
link error for .no_trim_symbol symbols", for another unconditionally
discarded allocated section.
Fixes: 029223d30162 ("objtool/klp: Add .klp.symid for sympos disambiguation")
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://patch.msgid.link/m24igzlbxf.fsf@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Diffstat (limited to 'tools/objtool')
| -rw-r--r-- | tools/objtool/klp-symid.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/tools/objtool/klp-symid.c b/tools/objtool/klp-symid.c index 21d8708013ab..b19f76dff13e 100644 --- a/tools/objtool/klp-symid.c +++ b/tools/objtool/klp-symid.c @@ -30,6 +30,7 @@ static const char * const discarded_secs[] = { ".discard", + ".exitcall.exit", ".modinfo", ".no_trim_symbol", "__tracepoint_check", |