Commit Graph

802 Commits

Author SHA1 Message Date
Josh Poimboeuf
acc8c6a798 objtool: Consolidate option validation
The option validations are a bit scattered, consolidate them.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/r/8f886502fda1d15f39d7351b70d4ebe5903da627.1741975349.git.jpoimboe@kernel.org
2025-03-17 11:36:01 +01:00
Josh Poimboeuf
764d956145 objtool: Remove --unret dependency on --rethunk
With unret validation enabled and IBT/LTO disabled, objtool runs on TUs
with --rethunk and on vmlinux.o with --unret.  So this dependency isn't
valid as they don't always run on the same object.

This error never triggered before because --unret is always coupled with
--noinstr, so the first conditional in opts_valid() returns early due to
opts.noinstr being true.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/c6f5635784a28ed4b10ac4307b1858e015e6eff0.1741975349.git.jpoimboe@kernel.org
2025-03-17 11:36:00 +01:00
Josh Poimboeuf
0a7fb6f07e objtool: Increase per-function WARN_FUNC() rate limit
Increase the per-function WARN_FUNC() rate limit from 1 to 2.  If the
number of warnings for a given function goes beyond 2, print "skipping
duplicate warning(s)".  This helps root out additional warnings in a
function that might be hiding behind the first one.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/aec318d66c037a51c9f376d6fb0e8ff32812a037.1741975349.git.jpoimboe@kernel.org
2025-03-17 11:36:00 +01:00
Josh Poimboeuf
dd95beba97 objtool: Update documentation
Fix some outdated information in the objtool doc.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/2552ee8b48631127bf269359647a7389edf5f002.1741975349.git.jpoimboe@kernel.org
2025-03-17 11:36:00 +01:00
Josh Poimboeuf
acae6b5bff objtool: Improve __noreturn annotation warning
Clarify what needs to be done to resolve the missing __noreturn warning.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/ab835a35d00bacf8aff0b56257df93f14fdd8224.1741975349.git.jpoimboe@kernel.org
2025-03-17 11:36:00 +01:00
Josh Poimboeuf
b745962cb9 objtool: Fix error handling inconsistencies in check()
Make sure all fatal errors are funneled through the 'out' label with a
negative ret.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/r/0f49d6a27a080b4012e84e6df1e23097f44cc082.1741975349.git.jpoimboe@kernel.org
2025-03-17 11:35:59 +01:00
Josh Poimboeuf
8085fcd78c x86/traps: Make exc_double_fault() consistently noreturn
The CONFIG_X86_ESPFIX64 version of exc_double_fault() can return to its
caller, but the !CONFIG_X86_ESPFIX64 version never does.  In the latter
case the compiler and/or objtool may consider it to be implicitly
noreturn.

However, due to the currently inflexible way objtool detects noreturns,
a function's noreturn status needs to be consistent across configs.

The current workaround for this issue is to suppress unreachable
warnings for exc_double_fault()'s callers.  Unfortunately that can
result in ORC coverage gaps and potentially worse issues like inert
static calls and silently disabled CPU mitigations.

Instead, prevent exc_double_fault() from ever being implicitly marked
noreturn by forcing a return behind a never-taken conditional.

Until a more integrated noreturn detection method exists, this is likely
the least objectionable workaround.

Fixes: 55eeab2a8a ("objtool: Ignore exc_double_fault() __noreturn warnings")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/r/d1f4026f8dc35d0de6cc61f2684e0cb6484009d1.1741975349.git.jpoimboe@kernel.org
2025-03-17 11:35:59 +01:00
Tiezhu Yang
88cbb468d4 objtool/LoongArch: Add support for goto table
The objtool program need to analysis the control flow of each object file
generated by compiler toolchain, it needs to know all the locations that
a branch instruction may jump into, if a jump table is used, objtool has
to correlate the jump instruction with the table.

On x86 (which is the only port supported by objtool before LoongArch),
there is a relocation type on the jump instruction and directly points
to the table. But on LoongArch, the relocation is on another kind of
instruction prior to the jump instruction, and also with scheduling it
is not very easy to tell the offset of that instruction from the jump
instruction. Furthermore, because LoongArch has -fsection-anchors (often
enabled at -O1 or above) the relocation may actually points to a section
anchor instead of the table itself.

For the jump table of switch cases, a GCC patch "LoongArch: Add support
to annotate tablejump" and a Clang patch "[LoongArch] Add options for
annotate tablejump" have been merged into the upstream mainline, it can
parse the additional section ".discard.tablejump_annotate" which stores
the jump info as pairs of addresses, each pair contains the address of
jump instruction and the address of jump table.

For the jump table of computed gotos, it is indeed not easy to implement
in the compiler, especially if there is more than one computed goto in a
function such as ___bpf_prog_run(). objdump kernel/bpf/core.o shows that
there are many table jump instructions in ___bpf_prog_run(), but there are
no relocations on the table jump instructions and to the table directly on
LoongArch.

Without the help of compiler, in order to figure out the address of goto
table for the special case of ___bpf_prog_run(), since the instruction
sequence is relatively single and stable, it makes sense to add a helper
find_reloc_of_rodata_c_jump_table() to find the relocation which points
to the section ".rodata..c_jump_table".

If find_reloc_by_table_annotate() failed, it means there is no relocation
info of switch table address in ".rela.discard.tablejump_annotate", then
objtool may find the relocation info of goto table ".rodata..c_jump_table"
with find_reloc_of_rodata_c_jump_table().

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/20250211115016.26913-6-yangtiezhu@loongson.cn
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-03-12 15:43:39 -07:00
Tiezhu Yang
b95f852d3a objtool/LoongArch: Add support for switch table
The objtool program need to analysis the control flow of each object file
generated by compiler toolchain, it needs to know all the locations that
a branch instruction may jump into, if a jump table is used, objtool has
to correlate the jump instruction with the table.

On x86 (which is the only port supported by objtool before LoongArch),
there is a relocation type on the jump instruction and directly points
to the table. But on LoongArch, the relocation is on another kind of
instruction prior to the jump instruction, and also with scheduling it
is not very easy to tell the offset of that instruction from the jump
instruction. Furthermore, because LoongArch has -fsection-anchors (often
enabled at -O1 or above) the relocation may actually points to a section
anchor instead of the table itself.

The good news is that after continuous analysis and discussion, at last
a GCC patch "LoongArch: Add support to annotate tablejump" and a Clang
patch "[LoongArch] Add options for annotate tablejump" have been merged
into the upstream mainline, the compiler changes make life much easier
for switch table support of objtool on LoongArch.

By now, there is an additional section ".discard.tablejump_annotate" to
store the jump info as pairs of addresses, each pair contains the address
of jump instruction and the address of jump table.

In order to find switch table, it is easy to parse the relocation section
".rela.discard.tablejump_annotate" to get table_sec and table_offset, the
rest process is somehow like x86.

Additionally, it needs to get each table size. When compiling on LoongArch,
there are unsorted table offsets of rodata if there exist many jump tables,
it will get the wrong table end and find the wrong table jump destination
instructions in add_jump_table().

Sort the rodata table offset by parsing ".rela.discard.tablejump_annotate"
and then get each table size of rodata corresponded with each table jump
instruction, it is used to check the table end and will break the process
when parsing ".rela.rodata" to avoid getting the wrong jump destination
instructions.

Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=0ee028f55640
Link: https://github.com/llvm/llvm-project/commit/4c2c17756739
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/20250211115016.26913-5-yangtiezhu@loongson.cn
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-03-12 15:43:38 -07:00
Tiezhu Yang
c4b93b0623 objtool: Handle PC relative relocation type
For the most part, an absolute relocation type is used for rodata.
In the case of STT_SECTION, reloc->sym->offset is always zero, for
the other symbol types, reloc_addend(reloc) is always zero, thus it
can use a simple statement "reloc->sym->offset + reloc_addend(reloc)"
to obtain the symbol offset for various symbol types.

When compiling on LoongArch, there exist PC relative relocation types
for rodata, it needs to calculate the symbol offset with "S + A - PC"
according to the spec of "ELF for the LoongArch Architecture".

If there is only one jump table in the rodata, the "PC" is the entry
address which is equal with the value of reloc_offset(reloc), at this
time, reloc_offset(table) is 0.

If there are many jump tables in the rodata, the "PC" is the offset
of the jump table's base address which is equal with the value of
reloc_offset(reloc) - reloc_offset(table).

So for LoongArch, if the relocation type is PC relative, it can use a
statement "reloc_offset(reloc) - reloc_offset(table)" to get the "PC"
value when calculating the symbol offset with "S + A - PC" for one or
many jump tables in the rodata.

Add an arch-specific function arch_jump_table_sym_offset() to assign
the symbol offset, for the most part that is an absolute relocation,
the default value is "reloc->sym->offset + reloc_addend(reloc)" in
the weak definition, it can be overridden by each architecture that
has different requirements.

Link: https://github.com/loongson/la-abi-specs/blob/release/laelf.adoc
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/20250211115016.26913-4-yangtiezhu@loongson.cn
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-03-12 15:43:38 -07:00
Tiezhu Yang
091bf313f8 objtool: Handle different entry size of rodata
In the most cases, the entry size of rodata is 8 bytes because the
relocation type is 64 bit. There are also 32 bit relocation types,
the entry size of rodata should be 4 bytes in this case.

Add an arch-specific function arch_reloc_size() to assign the entry
size of rodata for x86, powerpc and LoongArch.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/20250211115016.26913-3-yangtiezhu@loongson.cn
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-03-12 15:43:38 -07:00
Tiezhu Yang
ab6ce22b78 objtool: Handle various symbol types of rodata
In the relocation section ".rela.rodata" of each .o file compiled with
LoongArch toolchain, there are various symbol types such as STT_NOTYPE,
STT_OBJECT, STT_FUNC in addition to the usual STT_SECTION, it needs to
use reloc symbol offset instead of reloc addend to find the destination
instruction in find_jump_table() and add_jump_table().

For the most part, an absolute relocation type is used for rodata. In the
case of STT_SECTION, reloc->sym->offset is always zero, and for the other
symbol types, reloc_addend(reloc) is always zero, thus it can use a simple
statement "reloc->sym->offset + reloc_addend(reloc)" to obtain the symbol
offset for various symbol types.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/20250211115016.26913-2-yangtiezhu@loongson.cn
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-03-12 15:43:38 -07:00
David Engraf
bf71940fc1 objtool: Hide unnecessary compiler error message
The check for using old libelf prints an error message when libelf.h is
not available but does not abort. This may confuse so hide the compiler
error message.

Signed-off-by: David Engraf <david.engraf@sysgo.com>
Link: https://lore.kernel.org/r/20250203073610.206000-1-david.engraf@sysgo.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-03-12 15:43:38 -07:00
Ingo Molnar
71c2ff150f Merge branch 'x86/asm' into x86/core, to pick up dependent commits
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2025-03-04 20:29:35 +01:00
Ingo Molnar
1b4c36f9b1 Merge branch 'x86/urgent' into x86/cpu, to pick up dependent commits
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2025-03-04 11:15:26 +01:00
Josh Poimboeuf
4e32645cd8 x86/smp: Fix mwait_play_dead() and acpi_processor_ffh_play_dead() noreturn behavior
Fix some related issues (done in a single patch to avoid introducing
intermediate bisect warnings):

  1) The SMP version of mwait_play_dead() doesn't return, but its
     !SMP counterpart does.  Make its calling behavior consistent by
     resolving the !SMP version to a BUG().  It should never be called
     anyway, this just enforces that at runtime and enables its callers
     to be marked as __noreturn.

  2) While the SMP definition of mwait_play_dead() is annotated as
     __noreturn, the declaration isn't.  Nor is it listed in
     tools/objtool/noreturns.h.  Fix that.

  3) Similar to #1, the SMP version of acpi_processor_ffh_play_dead()
     doesn't return but its !SMP counterpart does.  Make the !SMP
     version a BUG().  It should never be called.

  4) acpi_processor_ffh_play_dead() doesn't return, but is lacking any
     __noreturn annotations.  Fix that.

This fixes the following objtool warnings:

  vmlinux.o: warning: objtool: acpi_processor_ffh_play_dead+0x67: mwait_play_dead() is missing a __noreturn annotation
  vmlinux.o: warning: objtool: acpi_idle_play_dead+0x3c: acpi_processor_ffh_play_dead() is missing a __noreturn annotation

Fixes: a7dd183f0b ("x86/smp: Allow calling mwait_play_dead with an arbitrary hint")
Fixes: 541ddf31e3 ("ACPI/processor_idle: Add FFH state handling")
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/e885c6fa9e96a61471b33e48c2162d28b15b14c5.1740962711.git.jpoimboe@kernel.org
2025-03-04 11:14:25 +01:00
Ingo Molnar
1fff9f8730 Merge tag 'v6.14-rc5' into x86/core, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2025-03-03 21:05:45 +01:00
Linus Torvalds
ad69e02128 Merge tag 'objtool-urgent-2025-02-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fixes from Ingo Molnar:
 "Fix an objtool false positive, and objtool related build warnings that
  happens on PIE-enabled architectures such as LoongArch"

* tag 'objtool-urgent-2025-02-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Add bch2_trans_unlocked_or_in_restart_error() to bcachefs noreturns
  objtool: Fix C jump table annotations for Clang
  vmlinux.lds: Ensure that const vars with relocations are mapped R/O
2025-02-28 16:45:36 -08:00
Christophe Leroy
bb7f054f4d objtool/powerpc: Add support for decoding all types of uncond branches
Add support for 'bla' instruction.

This is done by 'flagging' the address as an absolute address so that
arch_jump_destination() can calculate it as expected. Because code is
_always_ 4 bytes aligned, use bit 30 as flag.

Also add support for 'b' and 'ba' instructions. Objtool call them jumps.

And make sure the special 'bl .+4' used by clang in relocatable code is
not seen as an 'unannotated intra-function call'. clang should use the
special 'bcl 20,31,.+4' form like gcc but for the time being it does not
so lets work around that.

Link: https://github.com/llvm/llvm-project/issues/128644
Reviewed-by: Segher Boessenkool <segher@kewrnel.crashing.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/bf0b4d554547bc34fa3d1af5b4e62a84c0bc182b.1740470510.git.christophe.leroy@csgroup.eu
2025-02-26 21:09:43 +05:30
Linus Torvalds
9f5270d758 Merge tag 'perf-tools-fixes-for-v6.14-2-2025-02-25' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools
Pull perf tools fixes from Arnaldo Carvalho de Melo:

 - Fix tools/ quiet build Makefile infrastructure that was broken when
   working on tools/perf/ without testing on other tools/ living
   utilities.

* tag 'perf-tools-fixes-for-v6.14-2-2025-02-25' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools:
  tools: Remove redundant quiet setup
  tools: Unify top-level quiet infrastructure
2025-02-25 13:32:32 -08:00
Youling Tang
b4ae43b053 objtool: Add bch2_trans_unlocked_or_in_restart_error() to bcachefs noreturns
Fix the following objtool warning during build time:

  fs/bcachefs/btree_cache.o: warning: objtool: btree_node_lock.constprop.0() falls through to next function bch2_recalc_btree_reserve()
  fs/bcachefs/btree_update.o: warning: objtool: bch2_trans_update_get_key_cache() falls through to next function need_whiteout_for_snapshot()

bch2_trans_unlocked_or_in_restart_error() is an Obviously Correct (tm)
panic() wrapper, add it to the list of known noreturns.

Fixes: b318882022 ("bcachefs: bch2_trans_verify_not_unlocked_or_in_restart()")
Reported-by: k2ci <kernel-bot@kylinos.cn>
Signed-off-by: Youling Tang <tangyouling@kylinos.cn>
Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev>
Link: https://lore.kernel.org/r/20250218064230.219997-1-youling.tang@linux.dev
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-02-25 10:16:31 -08:00
Ard Biesheuvel
73cfc53cc3 objtool: Fix C jump table annotations for Clang
A C jump table (such as the one used by the BPF interpreter) is a const
global array of absolute code addresses, and this means that the actual
values in the table may not be known until the kernel is booted (e.g.,
when using KASLR or when the kernel VA space is sized dynamically).

When using PIE codegen, the compiler will default to placing such const
global objects in .data.rel.ro (which is annotated as writable), rather
than .rodata (which is annotated as read-only). As C jump tables are
explicitly emitted into .rodata, this used to result in warnings for
LoongArch builds (which uses PIE codegen for the entire kernel) like

  Warning: setting incorrect section attributes for .rodata..c_jump_table

due to the fact that the explicitly specified .rodata section inherited
the read-write annotation that the compiler uses for such objects when
using PIE codegen.

This warning was suppressed by explicitly adding the read-only
annotation to the __attribute__((section(""))) string, by commit

  c5b1184dec ("compiler.h: specify correct attribute for .rodata..c_jump_table")

Unfortunately, this hack does not work on Clang's integrated assembler,
which happily interprets the appended section type and permission
specifiers as part of the section name, which therefore no longer
matches the hard-coded pattern '.rodata..c_jump_table' that objtool
expects, causing it to emit a warning

  kernel/bpf/core.o: warning: objtool: ___bpf_prog_run+0x20: sibling call from callable instruction with modified stack frame

Work around this, by emitting C jump tables into .data.rel.ro instead,
which is treated as .rodata by the linker script for all builds, not
just PIE based ones.

Fixes: c5b1184dec ("compiler.h: specify correct attribute for .rodata..c_jump_table")
Tested-by: Tiezhu Yang <yangtiezhu@loongson.cn> # on LoongArch
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250221135704.431269-6-ardb+git@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-02-25 09:46:16 -08:00
Charlie Jenkins
42367eca76 tools: Remove redundant quiet setup
Q is exported from Makefile.include so it is not necessary to manually
set it.

Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <qmo@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Benjamin Tissoires <bentiss@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Mykola Lysenko <mykolal@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20250213-quiet_tools-v3-2-07de4482a581@rivosinc.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2025-02-18 16:27:43 -03:00
Ingo Molnar
e8f925c320 Merge tag 'v6.14-rc3' into x86/core, to pick up fixes
Pick up upstream x86 fixes before applying new patches.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2025-02-18 11:07:15 +01:00
Linus Torvalds
592c358ea9 Merge tag 'objtool_urgent_for_v6.14_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fixes from Borislav Petkov:

 - Move a warning about a lld.ld breakage into the verbose setting as
   said breakage has been fixed in the meantime

 - Teach objtool to ignore dangling jump table entries added by Clang

* tag 'objtool_urgent_for_v6.14_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Move dodgy linker warn to verbose
  objtool: Ignore dangling jump table entries
2025-02-16 10:30:58 -08:00
Peter Zijlstra
ab9fea5948 x86/alternative: Simplify callthunk patching
Now that paravirt call patching is implemented using alternatives, it
is possible to avoid having to patch the alternative sites by
including the altinstr_replacement calls in the call_sites list.

This means we're now stacking relative adjustments like so:

  callthunks_patch_builtin_calls():
    patches all function calls to target: func() -> func()-10
    since the CALL accounting lives in the CALL_PADDING.

    This explicitly includes .altinstr_replacement

  alt_replace_call():
    patches: x86_BUG() -> target()

    this patching is done in a relative manner, and will preserve
    the above adjustment, meaning that with calldepth patching it
    will do: x86_BUG()-10 -> target()-10

  apply_relocation():
    does code relocation, and adjusts all RIP-relative instructions
    to the new location, also in a relative manner.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20250207122546.617187089@infradead.org
2025-02-14 10:32:06 +01:00
Miguel Ojeda
cee6f9a9c8 objtool/rust: add one more noreturn Rust function
Starting with Rust 1.85.0 (currently in beta, to be released 2025-02-20),
under some kernel configurations with `CONFIG_RUST_DEBUG_ASSERTIONS=y`,
one may trigger a new `objtool` warning:

    rust/kernel.o: warning: objtool: _R...securityNtB2_11SecurityCtx8as_bytes()
    falls through to next function _R...core3ops4drop4Drop4drop()

due to a call to the `noreturn` symbol:

    core::panicking::assert_failed::<usize, usize>

Thus add it to the list so that `objtool` knows it is actually `noreturn`.
Do so matching with `strstr` since it is a generic.

See commit 56d680dd23 ("objtool/rust: list `noreturn` Rust functions")
for more details.

Cc: stable@vger.kernel.org # Needed in 6.12.y and 6.13.y only (Rust is pinned in older LTSs).
Fixes: 56d680dd23 ("objtool/rust: list `noreturn` Rust functions")
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20250112143951.751139-1-ojeda@kernel.org
[ Updated Cc: stable@ to include 6.13.y. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-02-12 23:26:48 +01:00
Peter Zijlstra
7e501637bd objtool: Move dodgy linker warn to verbose
The lld.ld borkage is fixed in the latest llvm release (?) but will
not be backported, meaning we're stuck with broken linker for a fair
while.

Lets not spam all clang build logs and move warning to verbose.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2025-02-08 15:43:08 +01:00
Josh Poimboeuf
3724062ca2 objtool: Ignore dangling jump table entries
Clang sometimes leaves dangling unused jump table entries which point to
the end of the function.  Ignore them.

Closes: https://lore.kernel.org/20250113235835.vqgvb7cdspksy5dn@jpoimboe
Reported-by: Klaus Kusche <klaus.kusche@computerix.info>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/ee25c0b7e80113e950bd1d4c208b671d35774ff4.1736891751.git.jpoimboe@kernel.org
2025-02-08 15:43:08 +01:00
Linus Torvalds
a6640c8c2f Merge tag 'objtool-core-2025-01-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar:

 - Introduce the generic section-based annotation infrastructure a.k.a.
   ASM_ANNOTATE/ANNOTATE (Peter Zijlstra)

 - Convert various facilities to ASM_ANNOTATE/ANNOTATE: (Peter Zijlstra)
    - ANNOTATE_NOENDBR
    - ANNOTATE_RETPOLINE_SAFE
    - instrumentation_{begin,end}()
    - VALIDATE_UNRET_BEGIN
    - ANNOTATE_IGNORE_ALTERNATIVE
    - ANNOTATE_INTRA_FUNCTION_CALL
    - {.UN}REACHABLE

 - Optimize the annotation-sections parsing code (Peter Zijlstra)

 - Centralize annotation definitions in <linux/objtool.h>

 - Unify & simplify the barrier_before_unreachable()/unreachable()
   definitions (Peter Zijlstra)

 - Convert unreachable() calls to BUG() in x86 code, as unreachable()
   has unreliable code generation (Peter Zijlstra)

 - Remove annotate_reachable() and annotate_unreachable(), as it's
   unreliable against compiler optimizations (Peter Zijlstra)

 - Fix non-standard ANNOTATE_REACHABLE annotation order (Peter Zijlstra)

 - Robustify the annotation code by warning about unknown annotation
   types (Peter Zijlstra)

 - Allow arch code to discover jump table size, in preparation of
   annotated jump table support (Ard Biesheuvel)

* tag 'objtool-core-2025-01-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm: Convert unreachable() to BUG()
  objtool: Allow arch code to discover jump table size
  objtool: Warn about unknown annotation types
  objtool: Fix ANNOTATE_REACHABLE to be a normal annotation
  objtool: Convert {.UN}REACHABLE to ANNOTATE
  objtool: Remove annotate_{,un}reachable()
  loongarch: Use ASM_REACHABLE
  x86: Convert unreachable() to BUG()
  unreachable: Unify
  objtool: Collect more annotations in objtool.h
  objtool: Collapse annotate sequences
  objtool: Convert ANNOTATE_INTRA_FUNCTION_CALL to ANNOTATE
  objtool: Convert ANNOTATE_IGNORE_ALTERNATIVE to ANNOTATE
  objtool: Convert VALIDATE_UNRET_BEGIN to ANNOTATE
  objtool: Convert instrumentation_{begin,end}() to ANNOTATE
  objtool: Convert ANNOTATE_RETPOLINE_SAFE to ANNOTATE
  objtool: Convert ANNOTATE_NOENDBR to ANNOTATE
  objtool: Generic annotation infrastructure
2025-01-21 10:13:11 -08:00
Linus Torvalds
bcfac5530a Merge tag 'objtool-urgent-2024-12-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fix from Ingo Molnar:
 "Fix false positive objtool build warning related to a noreturn
  function in the bcachefs code"

* tag 'objtool-urgent-2024-12-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Add bch2_trans_unlocked_error() to bcachefs noreturns
2024-12-29 10:07:40 -08:00
chenchangcheng
31ad36a271 objtool: Add bch2_trans_unlocked_error() to bcachefs noreturns
Fix the following objtool warning during build time:

    fs/bcachefs/btree_trans_commit.o: warning: objtool: bch2_trans_commit_write_locked.isra.0() falls through to next function do_bch2_trans_commit.isra.0()
    fs/bcachefs/btree_trans_commit.o: warning: objtool: .text: unexpected end of section
......
    fs/bcachefs/btree_update.o: warning: objtool: bch2_trans_update_get_key_cache() falls through to next function flush_new_cached_update()
    fs/bcachefs/btree_update.o: warning: objtool: flush_new_cached_update() falls through to next function bch2_trans_update_by_path()

bch2_trans_unlocked_error() is an Obviously Correct (tm) panic() wrapper,
add it to the list of known noreturns.

[ mingo: Improved the changelog ]

Fixes: fd104e2967 ("bcachefs: bch2_trans_verify_not_unlocked()")
Signed-off-by: chenchangcheng <chenchangcheng@kylinos.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20241220074847.3418134-1-ccc194101@163.com
2024-12-29 09:52:21 +01:00
Juergen Gross
dda014ba59 objtool/x86: allow syscall instruction
The syscall instruction is used in Xen PV mode for doing hypercalls.
Allow syscall to be used in the kernel in case it is tagged with an
unwind hint for objtool.

This is part of XSA-466 / CVE-2024-53241.

Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Co-developed-by: Peter Zijlstra <peterz@infradead.org>
2024-12-13 09:28:21 +01:00
Ard Biesheuvel
c3cb6c158c objtool: Allow arch code to discover jump table size
In preparation for adding support for annotated jump tables, where
ELF relocations and symbols are used to describe the locations of jump
tables in the executable, refactor the jump table discovery logic so the
table size can be returned from arch_find_switch_table().

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20241011170847.334429-12-ardb+git@google.com
2024-12-02 12:24:29 +01:00
Peter Zijlstra
e7e0eb53c2 objtool: Warn about unknown annotation types
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094312.611961175@infradead.org
2024-12-02 12:01:45 +01:00
Peter Zijlstra
87116ae6da objtool: Fix ANNOTATE_REACHABLE to be a normal annotation
Currently REACHABLE is weird for being on the instruction after the
instruction it modifies.

Since all REACHABLE annotations have an explicit instruction, flip
them around.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094312.494176035@infradead.org
2024-12-02 12:01:44 +01:00
Peter Zijlstra
e7a174fb43 objtool: Convert {.UN}REACHABLE to ANNOTATE
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094312.353431347@infradead.org
2024-12-02 12:01:44 +01:00
Peter Zijlstra
06e2474598 objtool: Remove annotate_{,un}reachable()
There are no users of annotate_reachable() left.

And the annotate_unreachable() usage in unreachable() is plain wrong;
it will hide dangerous fall-through code-gen.

Remove both.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094312.235637588@infradead.org
2024-12-02 12:01:44 +01:00
Peter Zijlstra
a8a330dd99 objtool: Collapse annotate sequences
Reduce read_annotate() runs by collapsing subsequent runs into a
single call.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.688871544@infradead.org
2024-12-02 12:01:42 +01:00
Peter Zijlstra
112765ca1c objtool: Convert ANNOTATE_INTRA_FUNCTION_CALL to ANNOTATE
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.584892071@infradead.org
2024-12-02 12:01:42 +01:00
Peter Zijlstra
f0cd57c35a objtool: Convert ANNOTATE_IGNORE_ALTERNATIVE to ANNOTATE
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.465691316@infradead.org
2024-12-02 12:01:42 +01:00
Peter Zijlstra
18aa6118a1 objtool: Convert VALIDATE_UNRET_BEGIN to ANNOTATE
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.358508242@infradead.org
2024-12-02 12:01:42 +01:00
Peter Zijlstra
317f2a6461 objtool: Convert instrumentation_{begin,end}() to ANNOTATE
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.245980207@infradead.org
2024-12-02 12:01:41 +01:00
Peter Zijlstra
bf5febebd9 objtool: Convert ANNOTATE_RETPOLINE_SAFE to ANNOTATE
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.145275669@infradead.org
2024-12-02 12:01:41 +01:00
Peter Zijlstra
22c3d58079 objtool: Convert ANNOTATE_NOENDBR to ANNOTATE
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.042140333@infradead.org
2024-12-02 12:01:41 +01:00
Peter Zijlstra
2116b349e2 objtool: Generic annotation infrastructure
Avoid endless .discard.foo sections for each annotation, create a
single .discard.annotate_insn section that takes an annotation type along
with the instruction.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094310.932794537@infradead.org
2024-12-02 12:01:41 +01:00
Linus Torvalds
6a34dfa15d Merge tag 'kbuild-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:

 - Add generic support for built-in boot DTB files

 - Enable TAB cycling for dialog buttons in nconfig

 - Fix issues in streamline_config.pl

 - Refactor Kconfig

 - Add support for Clang's AutoFDO (Automatic Feedback-Directed
   Optimization)

 - Add support for Clang's Propeller, a profile-guided optimization.

 - Change the working directory to the external module directory for M=
   builds

 - Support building external modules in a separate output directory

 - Enable objtool for *.mod.o and additional kernel objects

 - Use lz4 instead of deprecated lz4c

 - Work around a performance issue with "git describe"

 - Refactor modpost

* tag 'kbuild-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (85 commits)
  kbuild: rename .tmp_vmlinux.kallsyms0.syms to .tmp_vmlinux0.syms
  gitignore: Don't ignore 'tags' directory
  kbuild: add dependency from vmlinux to resolve_btfids
  modpost: replace tdb_hash() with hash_str()
  kbuild: deb-pkg: add python3:native to build dependency
  genksyms: reduce indentation in export_symbol()
  modpost: improve error messages in device_id_check()
  modpost: rename alias symbol for MODULE_DEVICE_TABLE()
  modpost: rename variables in handle_moddevtable()
  modpost: move strstarts() to modpost.h
  modpost: convert do_usb_table() to a generic handler
  modpost: convert do_of_table() to a generic handler
  modpost: convert do_pnp_device_entry() to a generic handler
  modpost: convert do_pnp_card_entries() to a generic handler
  modpost: call module_alias_printf() from all do_*_entry() functions
  modpost: pass (struct module *) to do_*_entry() functions
  modpost: remove DEF_FIELD_ADDR_VAR() macro
  modpost: deduplicate MODULE_ALIAS() for all drivers
  modpost: introduce module_alias_printf() helper
  modpost: remove unnecessary check in do_acpi_entry()
  ...
2024-11-30 13:41:50 -08:00
Rong Xu
d5dc958361 kbuild: Add Propeller configuration for kernel build
Add the build support for using Clang's Propeller optimizer. Like
AutoFDO, Propeller uses hardware sampling to gather information
about the frequency of execution of different code paths within a
binary. This information is then used to guide the compiler's
optimization decisions, resulting in a more efficient binary.

The support requires a Clang compiler LLVM 19 or later, and the
create_llvm_prof tool
(https://github.com/google/autofdo/releases/tag/v0.30.1). This
commit is limited to x86 platforms that support PMU features
like LBR on Intel machines and AMD Zen3 BRS.

Here is an example workflow for building an AutoFDO+Propeller
optimized kernel:

1) Build the kernel on the host machine, with AutoFDO and Propeller
   build config
      CONFIG_AUTOFDO_CLANG=y
      CONFIG_PROPELLER_CLANG=y
   then
      $ make LLVM=1 CLANG_AUTOFDO_PROFILE=<autofdo_profile>

“<autofdo_profile>” is the profile collected when doing a non-Propeller
AutoFDO build. This step builds a kernel that has the same optimization
level as AutoFDO, plus a metadata section that records basic block
information. This kernel image runs as fast as an AutoFDO optimized
kernel.

2) Install the kernel on test/production machines.

3) Run the load tests. The '-c' option in perf specifies the sample
   event period. We suggest using a suitable prime number,
   like 500009, for this purpose.
   For Intel platforms:
      $ perf record -e BR_INST_RETIRED.NEAR_TAKEN:k -a -N -b -c <count> \
        -o <perf_file> -- <loadtest>
   For AMD platforms:
      The supported system are: Zen3 with BRS, or Zen4 with amd_lbr_v2
      # To see if Zen3 support LBR:
      $ cat proc/cpuinfo | grep " brs"
      # To see if Zen4 support LBR:
      $ cat proc/cpuinfo | grep amd_lbr_v2
      # If the result is yes, then collect the profile using:
      $ perf record --pfm-events RETIRED_TAKEN_BRANCH_INSTRUCTIONS:k -a \
        -N -b -c <count> -o <perf_file> -- <loadtest>

4) (Optional) Download the raw perf file to the host machine.

5) Generate Propeller profile:
   $ create_llvm_prof --binary=<vmlinux> --profile=<perf_file> \
     --format=propeller --propeller_output_module_name \
     --out=<propeller_profile_prefix>_cc_profile.txt \
     --propeller_symorder=<propeller_profile_prefix>_ld_profile.txt

   “create_llvm_prof” is the profile conversion tool, and a prebuilt
   binary for linux can be found on
   https://github.com/google/autofdo/releases/tag/v0.30.1 (can also build
   from source).

   "<propeller_profile_prefix>" can be something like
   "/home/user/dir/any_string".

   This command generates a pair of Propeller profiles:
   "<propeller_profile_prefix>_cc_profile.txt" and
   "<propeller_profile_prefix>_ld_profile.txt".

6) Rebuild the kernel using the AutoFDO and Propeller profile files.
      CONFIG_AUTOFDO_CLANG=y
      CONFIG_PROPELLER_CLANG=y
   and
      $ make LLVM=1 CLANG_AUTOFDO_PROFILE=<autofdo_profile> \
        CLANG_PROPELLER_PROFILE_PREFIX=<propeller_profile_prefix>

Co-developed-by: Han Shen <shenhan@google.com>
Signed-off-by: Han Shen <shenhan@google.com>
Signed-off-by: Rong Xu <xur@google.com>
Suggested-by: Sriraman Tallam <tmsriram@google.com>
Suggested-by: Krzysztof Pszeniczny <kpszeniczny@google.com>
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Suggested-by: Stephane Eranian <eranian@google.com>
Tested-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-11-27 09:38:27 +09:00
Linus Torvalds
c01f664e4c Merge tag 'reiserfs_delete' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
Pull reiserfs removal from Jan Kara:
 "The deprecation period of reiserfs is ending at the end of this year
  so it is time to remove it"

* tag 'reiserfs_delete' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  reiserfs: The last commit
2024-11-21 09:50:18 -08:00
Peter Zijlstra
d5173f7537 objtool: Exclude __tracepoints data from ENDBR checks
For some, as of yet unexplained reason, Clang-19, but not GCC,
generates and endless stream of:

drivers/iio/imu/bno055/bno055_ser.o: warning: objtool: __tracepoint_send_chunk+0x20: data relocation to !ENDBR: __SCT__tp_func_send_chunk+0x0
drivers/iio/imu/bno055/bno055_ser.o: warning: objtool: __tracepoint_cmd_retry+0x20: data relocation to !ENDBR: __SCT__tp_func_cmd_retry+0x0
drivers/iio/imu/bno055/bno055_ser.o: warning: objtool: __tracepoint_write_reg+0x20: data relocation to !ENDBR: __SCT__tp_func_write_reg+0x0
drivers/iio/imu/bno055/bno055_ser.o: warning: objtool: __tracepoint_read_reg+0x20: data relocation to !ENDBR: __SCT__tp_func_read_reg+0x0
drivers/iio/imu/bno055/bno055_ser.o: warning: objtool: __tracepoint_recv+0x20: data relocation to !ENDBR: __SCT__tp_func_recv+0x0

Which is entirely correct, but harmless. Add the __tracepoints section
to the exclusion list.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20241108184618.GG38786@noisy.programming.kicks-ass.net
2024-11-11 11:49:42 +01:00