linux-toradex.git/tools/objtool/elf.c, branch v6.15-rc7

objtool: Change "warning:" to "error: " for fatal errors

2025-04-01T07:07:13+00:00

This is similar to GCC's behavior and makes it more obvious why the
build failed.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Cc: Linus Torvalds 
Link: https://lore.kernel.org/r/0ea76f4b0e7a370711ed9f75fd0792bb5979c2bf.1743481539.git.jpoimboe@kernel.org

objtool: Improve error handling

2025-03-25T08:20:27+00:00

Fix some error handling issues, improve error messages, properly
distinguish betwee errors and warnings, and generally try to make all
the error handling more consistent.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Cc: Linus Torvalds 
Link: https://lore.kernel.org/r/3094bb4463dad29b6bd1bea03848d1571ace771c.1742852846.git.jpoimboe@kernel.org

objtool: Fix detection of consecutive jump tables on Clang 20

2025-03-25T08:20:25+00:00

The jump table detection code assumes jump tables are in the same order
as their corresponding indirect branches.  That's apparently not always
true with Clang 20.

Fix that by changing how multiple jump tables are detected.  In the
first detection pass, mark the beginning of each jump table so the
second pass can tell where one ends and the next one begins.

Fixes the following warnings:

  vmlinux.o: warning: objtool: SiS_GetCRT2Ptr+0x1ad: stack state mismatch: cfa1=4+8 cfa2=5+16
  sound/core/seq/snd-seq.o: warning: objtool: cc_ev_to_ump_midi2+0x589: return with modified stack frame

Fixes: be2f0b1e1264 ("objtool: Get rid of reloc->jump_table_start")
Reported-by: kernel test robot 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Cc: Nathan Chancellor 
Cc: Nick Desaulniers 
Cc: Linus Torvalds 
Link: https://lore.kernel.org/r/141752fff614eab962dba6bdfaa54aa67ff03bba.1742852846.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/oe-kbuild-all/202503171547.LlCTJLQL-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202503200535.J3hAvcjw-lkp@intel.com/

objtool: Add --output option

2025-03-17T10:36:01+00:00

Add option to allow writing the changed binary to a separate file rather
than changing it in place.

Libelf makes this suprisingly hard, so take the easy way out and just
copy the file before editing it.

Also steal the -o short option from --orc.  Nobody will notice ;-)

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/r/0da308d42d82b3bbed16a31a72d6bde52afcd6bd.1741975349.git.jpoimboe@kernel.org

objtool: Fix unreachable instruction warnings for weak functions

2024-11-06T13:41:10+00:00

In the presence of both weak and strong function definitions, the
linker drops the weak symbol in favor of a strong symbol, but
leaves the code in place. Code in ignore_unreachable_insn() has
some heuristics to suppress the warning, but it does not work when
-ffunction-sections is enabled.

Suppose function foo has both strong and weak definitions.
Case 1: The strong definition has an annotated section name,
like .init.text. Only the weak definition will be placed into
.text.foo. But since the section has no symbols, there will be no
"hole" in the section.

Case 2: Both sections are without an annotated section name.
Both will be placed into .text.foo section, but there will be only one
symbol (the strong one). If the weak code is before the strong code,
there is no "hole" as it fails to find the right-most symbol before
the offset.

The fix is to use the first node to compute the hole if hole.sym
is empty. If there is no symbol in the section, the first node
will be NULL, in which case, -1 is returned to skip the whole
section.

Co-developed-by: Han Shen 
Signed-off-by: Han Shen 
Signed-off-by: Rong Xu 
Suggested-by: Sriraman Tallam 
Suggested-by: Krzysztof Pszeniczny 
Tested-by: Yonghong Song 
Tested-by: Yabin Cui 
Tested-by: Nathan Chancellor 
Reviewed-by: Kees Cook 
Acked-by: Josh Poimboeuf 
Signed-off-by: Masahiro Yamada

objtool: Remove max symbol name length limitation

2023-10-06T00:01:28+00:00

If one of the symbols processed by read_symbols() happens to have a
.cold variant with a name longer than objtool's MAX_NAME_LEN limit, the
build fails.

Avoid this problem by just using strndup() to copy the parent function's
name, rather than strncpy()ing it onto the stack.

Signed-off-by: Aaron Plattner 
Link: https://lore.kernel.org/r/41e94cfea1d9131b758dd637fecdeacd459d4584.1696355111.git.aplattner@nvidia.com
Signed-off-by: Josh Poimboeuf

objtool: initialize all of struct elf

2023-07-10T07:52:28+00:00

Function elf_open_read() only zero initializes the initial part of
allocated struct elf; num_relocs member was recently added outside the
zeroed part so that it was left uninitialized, resulting in build failures
on some systems.

The partial initialization is a relic of times when struct elf had large
hash tables embedded. This is no longer the case so remove the trap and
initialize the whole structure instead.

Fixes: eb0481bbc4ce ("objtool: Fix reloc_hash size")
Signed-off-by: Michal Kubecek 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/20230629102051.42E8360467@lion.mk-sys.cz

objtool: Skip reading DWARF section data

2023-06-07T17:03:27+00:00

Objtool doesn't use DWARF at all, and the DWARF sections' data take up a
lot of memory.  Skip reading them.

Note this only skips the DWARF base sections, not the rela sections.
The relas are needed because their symbol references may need to be
reindexed if any local symbols get added by elf_create_symbol().

Also note the DWARF data will eventually be read by libelf anyway, when
writing the object file.  But that's fine, the goal here is to reduce
*peak* memory usage, and the previous patch (which freed insn memory)
gave some breathing room.  So the allocation gets shifted to a later
time, resulting in lower peak memory usage.

With allyesconfig + CONFIG_DEBUG_INFO:

- Before: peak heap memory consumption: 29.93G
- After:  peak heap memory consumption: 25.47G

Link: https://lore.kernel.org/r/52a9698835861dd35f2ec35c49f96d0bb39fb177.1685464332.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf

objtool: Get rid of reloc->rel[a]

2023-06-07T17:03:26+00:00

Get the relocation entry info from the underlying rsec->data.

With allyesconfig + CONFIG_DEBUG_INFO:

- Before: peak heap memory consumption: 35.12G
- After:  peak heap memory consumption: 29.93G

Link: https://lore.kernel.org/r/2be32323de6d8cc73179ee0ff14b71f4e7cefaa0.1685464332.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf

objtool: Shrink elf hash nodes

2023-06-07T17:03:25+00:00

Instead of using hlist for the 'struct elf' hashes, use a custom
single-linked list scheme.

With allyesconfig + CONFIG_DEBUG_INFO:

- Before: peak heap memory consumption: 36.89G
- After:  peak heap memory consumption: 35.12G

Link: https://lore.kernel.org/r/6e8cd305ed22e743c30d6e72cfdc1be20fb94cd4.1685464332.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf