linux-toradex.git/tools/objtool/check.c, branch v6.19-rc2

objtool: Fix stack overflow in validate_branch()

2025-12-02T16:40:35+00:00

On an allmodconfig kernel compiled with Clang, objtool is segfaulting in
drivers/scsi/qla2xxx/qla2xxx.o due to a stack overflow in
validate_branch().

Due in part to KASAN being enabled, the qla2xxx code has a large number
of conditional jumps, causing objtool to go quite deep in its recursion.

By far the biggest offender of stack usage is the recently added
'prev_state' stack variable in validate_insn(), coming in at 328 bytes.

Move that variable (and its tracing usage) to handle_insn_ops() and make
handle_insn_ops() noinline to keep its stack frame outside the recursive
call chain.

Reported-by: Nathan Chancellor 
Fixes: fcb268b47a2f ("objtool: Trace instruction state changes during function validation")
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Link: https://patch.msgid.link/21bb161c23ca0d8c942a960505c0d327ca2dc7dc.1764691895.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/20251201202329.GA3225984@ax162

objtool: Provide access to feature and flags of group alternatives

2025-11-21T14:30:14+00:00

Each alternative of a group alternative depends on a specific
feature and flags. Provide access to the feature/flags for each
alternative as an attribute (feature) in struct alt_group.

Signed-off-by: Alexandre Chartre 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://patch.msgid.link/20251121095340.464045-26-alexandre.chartre@oracle.com

objtool: Preserve alternatives order

2025-11-21T14:30:12+00:00

Preserve the order in which alternatives are defined. Currently
objtool stores alternatives in a list in reverse order.

Signed-off-by: Alexandre Chartre 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://patch.msgid.link/20251121095340.464045-19-alexandre.chartre@oracle.com

objtool: Add the --disas= action

2025-11-21T14:30:12+00:00

Add the --disas= actions to disassemble the specified
functions. The function pattern can be a single function name (e.g.
--disas foo to disassemble the function with the name "foo"), or a shell
wildcard pattern (e.g. --disas foo* to disassemble all functions with a
name starting with "foo").

Signed-off-by: Alexandre Chartre 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://patch.msgid.link/20251121095340.464045-18-alexandre.chartre@oracle.com

objtool: Do not validate IBT for .return_sites and .call_sites

2025-11-21T14:30:12+00:00

The .return_sites and .call_sites sections reference text addresses,
but not with the intent to indirect branch to them, so they don't
need to be validated for IBT.

This is useful when running objtool on object files which already
have .return_sites or .call_sites sections, for example to re-run
objtool after it has reported an error or a warning.

Signed-off-by: Alexandre Chartre 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://patch.msgid.link/20251121095340.464045-17-alexandre.chartre@oracle.com

objtool: Improve tracing of alternative instructions

2025-11-21T14:30:11+00:00

When tracing function validation, improve the reporting of
alternative instruction by more clearly showing the different
alternatives beginning and end.

Signed-off-by: Alexandre Chartre 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://patch.msgid.link/20251121095340.464045-16-alexandre.chartre@oracle.com

objtool: Identify the different types of alternatives

2025-11-21T14:30:11+00:00

Alternative code, including jump table and exception table, is represented
with the same struct alternative structure. But there is no obvious way to
identify whether the struct represents alternative instructions, a jump
table or an exception table.

So add a type to struct alternative to clearly identify the type of
alternative.

Signed-off-by: Alexandre Chartre 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://patch.msgid.link/20251121095340.464045-14-alexandre.chartre@oracle.com

objtool: Trace instruction state changes during function validation

2025-11-21T14:30:10+00:00

During function validation, objtool maintains a per-instruction state,
in particular to track call frame information. When tracing validation,
print any instruction state changes.

Signed-off-by: Alexandre Chartre 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://patch.msgid.link/20251121095340.464045-12-alexandre.chartre@oracle.com

objtool: Add option to trace function validation

2025-11-21T14:30:09+00:00

Add an option to trace and have information during the validation
of specified functions. Functions are specified with the --trace
option which can be a single function name (e.g. --trace foo to
trace the function with the name "foo"), or a shell wildcard
pattern (e.g. --trace foo* to trace all functions with a name
starting with "foo").

Signed-off-by: Alexandre Chartre 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://patch.msgid.link/20251121095340.464045-11-alexandre.chartre@oracle.com

objtool: Record symbol name max length

2025-11-21T14:30:09+00:00

Keep track of the maximum length of symbol names. This will help
formatting the code flow between different functions.

Signed-off-by: Alexandre Chartre 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://patch.msgid.link/20251121095340.464045-10-alexandre.chartre@oracle.com