linux.git/tools/objtool, branch v6.5-rc2

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: Remove btrfs_assertfail() from the noreturn exceptions list

2023-06-30T00:27:47+00:00

The objtool merge in commit 6f612579be9d ("Merge tag 'objtool-core ...")
generated a semantic conflict that was not resolved.

The btrfs_assertfail() entry was removed from the noreturn list in
commit b831306b3b7d ("btrfs: print assertion failure report and stack
trace from the same line") because btrfs_assertfail() was changed from a
noreturn function into a macro.

The noreturn list was then moved from check.c to noreturns.h in commit
6245ce4ab670 ("objtool: Move noreturn function list to separate file"),
and should be removed from that post-merge as well.

Do it explicitly.

Cc: David Sterba 
Cc: Josh Poimboeuf 
Cc: Peter Zijlstra 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Linus Torvalds

Merge tag 'objtool-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-06-27T22:05:41+00:00

Pull objtool updates from Ingo Molar:
 "Build footprint & performance improvements:

   - Reduce memory usage with CONFIG_DEBUG_INFO=y

     In the worst case of an allyesconfig+CONFIG_DEBUG_INFO=y kernel,
     DWARF creates almost 200 million relocations, ballooning objtool's
     peak heap usage to 53GB. These patches reduce that to 25GB.

     On a distro-type kernel with kernel IBT enabled, they reduce
     objtool's peak heap usage from 4.2GB to 2.8GB.

     These changes also improve the runtime significantly.

  Debuggability improvements:

   - Add the unwind_debug command-line option, for more extend unwinding
     debugging output
   - Limit unreachable warnings to once per function
   - Add verbose option for disassembling affected functions
   - Include backtrace in verbose mode
   - Detect missing __noreturn annotations
   - Ignore exc_double_fault() __noreturn warnings
   - Remove superfluous global_noreturns entries
   - Move noreturn function list to separate file
   - Add __kunit_abort() to noreturns

  Unwinder improvements:

   - Allow stack operations in UNWIND_HINT_UNDEFINED regions
   - drm/vmwgfx: Add unwind hints around RBP clobber

  Cleanups:

   - Move the x86 entry thunk restore code into thunk functions
   - x86/unwind/orc: Use swap() instead of open coding it
   - Remove unnecessary/unused variables

  Fixes for modern stack canary handling"

* tag 'objtool-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (42 commits)
  x86/orc: Make the is_callthunk() definition depend on CONFIG_BPF_JIT=y
  objtool: Skip reading DWARF section data
  objtool: Free insns when done
  objtool: Get rid of reloc->rel[a]
  objtool: Shrink elf hash nodes
  objtool: Shrink reloc->sym_reloc_entry
  objtool: Get rid of reloc->jump_table_start
  objtool: Get rid of reloc->addend
  objtool: Get rid of reloc->type
  objtool: Get rid of reloc->offset
  objtool: Get rid of reloc->idx
  objtool: Get rid of reloc->list
  objtool: Allocate relocs in advance for new rela sections
  objtool: Add for_each_reloc()
  objtool: Don't free memory in elf_close()
  objtool: Keep GElf_Rel[a] structs synced
  objtool: Add elf_create_section_pair()
  objtool: Add mark_sec_changed()
  objtool: Fix reloc_hash size
  objtool: Consolidate rel/rela handling
  ...

Merge tag 'linux-kselftest-kunit-6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

2023-06-27T18:12:55+00:00

Pull KUnit updates from Shuah Khan:

 - kunit_add_action() API to defer a call until test exit

 - Update document to add kunit_add_action() usage notes

 - Changes to always run cleanup from a test kthread

 - Documentation updates to clarify cleanup usage (assertions should not
   be used in cleanup)

 - Documentation update to clearly indicate that exit functions should
   run even if init fails

 - Several fixes and enhancements to existing tests

* tag 'linux-kselftest-kunit-6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  MAINTAINERS: Add source tree entry for kunit
  Documentation: kunit: Rename references to kunit_abort()
  kunit: Move kunit_abort() call out of kunit_do_failed_assertion()
  kunit: Fix obsolete name in documentation headers (func->action)
  Documentation: Kunit: add MODULE_LICENSE to sample code
  kunit: Update kunit_print_ok_not_ok function
  kunit: Fix reporting of the skipped parameterized tests
  kunit/test: Add example test showing parameterized testing
  Documentation: kunit: Add usage notes for kunit_add_action()
  kunit: kmalloc_array: Use kunit_add_action()
  kunit: executor_test: Use kunit_add_action()
  kunit: Add kunit_add_action() to defer a call until test exit
  kunit: example: Provide example exit functions
  Documentation: kunit: Warn that exit functions run even if init fails
  Documentation: kunit: Note that assertions should not be used in cleanup
  kunit: Always run cleanup from a test kthread
  Documentation: kunit: Modular tests should not depend on KUNIT=y
  kunit: tool: undo type subscripts for subprocess.Popen

Merge tag 'x86_alternatives_for_v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-06-26T22:14:55+00:00

Pull x86 instruction alternatives updates from Borislav Petkov:

 - Up until now the Fast Short Rep Mov optimizations implied the
   presence of the ERMS CPUID flag. AMD decoupled them with a BIOS
   setting so decouple that dependency in the kernel code too

 - Teach the alternatives machinery to handle relocations

 - Make debug_alternative accept flags in order to see only that set of
   patching done one is interested in

 - Other fixes, cleanups and optimizations to the patching code

* tag 'x86_alternatives_for_v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/alternative: PAUSE is not a NOP
  x86/alternatives: Add cond_resched() to text_poke_bp_batch()
  x86/nospec: Shorten RESET_CALL_DEPTH
  x86/alternatives: Add longer 64-bit NOPs
  x86/alternatives: Fix section mismatch warnings
  x86/alternative: Optimize returns patching
  x86/alternative: Complicate optimize_nops() some more
  x86/alternative: Rewrite optimize_nops() some
  x86/lib/memmove: Decouple ERMS from FSRM
  x86/alternative: Support relocations in alternatives
  x86/alternative: Make debug-alternative selective

btrfs: print assertion failure report and stack trace from the same line

2023-06-19T11:59:31+00:00

Assertions reports are split into two parts, the exact file and location
of the condition and then the stack trace printed from
btrfs_assertfail(). This means all the stack traces report the same line
and this is what's typically reported by various tools, making it harder
to distinguish the reports.

  [403.2467] assertion failed: refcount_read(&block_group->refs) == 1, in fs/btrfs/block-group.c:4259
  [403.2479] ------------[ cut here ]------------
  [403.2484] kernel BUG at fs/btrfs/messages.c:259!
  [403.2488] invalid opcode: 0000 [#1] PREEMPT SMP KASAN
  [403.2493] CPU: 2 PID: 23202 Comm: umount Not tainted 6.2.0-rc4-default+ #67
  [403.2499] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552-rebuilt.opensuse.org 04/01/2014
  [403.2509] RIP: 0010:btrfs_assertfail+0x19/0x1b [btrfs]
  ...
  [403.2595] Call Trace:
  [403.2598]  
  [403.2601]  btrfs_free_block_groups.cold+0x52/0xae [btrfs]
  [403.2608]  close_ctree+0x6c2/0x761 [btrfs]
  [403.2613]  ? __wait_for_common+0x2b8/0x360
  [403.2618]  ? btrfs_cleanup_one_transaction.cold+0x7a/0x7a [btrfs]
  [403.2626]  ? mark_held_locks+0x6b/0x90
  [403.2630]  ? lockdep_hardirqs_on_prepare+0x13d/0x200
  [403.2636]  ? __call_rcu_common.constprop.0+0x1ea/0x3d0
  [403.2642]  ? trace_hardirqs_on+0x2d/0x110
  [403.2646]  ? __call_rcu_common.constprop.0+0x1ea/0x3d0
  [403.2652]  generic_shutdown_super+0xb0/0x1c0
  [403.2657]  kill_anon_super+0x1e/0x40
  [403.2662]  btrfs_kill_super+0x25/0x30 [btrfs]
  [403.2668]  deactivate_locked_super+0x4c/0xc0

By making btrfs_assertfail a macro we'll get the same line number for
the BUG output:

  [63.5736] assertion failed: 0, in fs/btrfs/super.c:1572
  [63.5758] ------------[ cut here ]------------
  [63.5782] kernel BUG at fs/btrfs/super.c:1572!
  [63.5807] invalid opcode: 0000 [#2] PREEMPT SMP KASAN
  [63.5831] CPU: 0 PID: 859 Comm: mount Tainted: G      D            6.3.0-rc7-default+ #2062
  [63.5868] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014
  [63.5905] RIP: 0010:btrfs_mount+0x24/0x30 [btrfs]
  [63.5964] RSP: 0018:ffff88800e69fcd8 EFLAGS: 00010246
  [63.5982] RAX: 000000000000002d RBX: ffff888008fc1400 RCX: 0000000000000000
  [63.6004] RDX: 0000000000000000 RSI: ffffffffb90fd868 RDI: ffffffffbcc3ff20
  [63.6026] RBP: ffffffffc081b200 R08: 0000000000000001 R09: ffff88800e69fa27
  [63.6046] R10: ffffed1001cd3f44 R11: 0000000000000001 R12: ffff888005a3c370
  [63.6062] R13: ffffffffc058e830 R14: 0000000000000000 R15: 00000000ffffffff
  [63.6081] FS:  00007f7b3561f800(0000) GS:ffff88806c600000(0000) knlGS:0000000000000000
  [63.6105] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [63.6120] CR2: 00007fff83726e10 CR3: 0000000002a9e000 CR4: 00000000000006b0
  [63.6137] Call Trace:
  [63.6143]  
  [63.6148]  legacy_get_tree+0x80/0xd0
  [63.6158]  vfs_get_tree+0x43/0x120
  [63.6166]  do_new_mount+0x1f3/0x3d0
  [63.6176]  ? do_add_mount+0x140/0x140
  [63.6187]  ? cap_capable+0xa4/0xe0
  [63.6197]  path_mount+0x223/0xc10

This comes at a cost of bloating the final btrfs.ko module due all the
inlining, as long as assertions are compiled in. This is a must for
debugging builds but this is often enabled on release builds too.

Release build:

   text    data     bss     dec     hex filename
1251676   20317   16088 1288081  13a791 pre/btrfs.ko
1260612   29473   16088 1306173  13ee3d post/btrfs.ko

DELTA: +8936

CC: Josh Poimboeuf 
Signed-off-by: David Sterba

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: Free insns when done

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

Free the decoded instructions as they're no longer needed after this
point.  This frees up a big chunk of heap, which will come handy when
skipping the reading of DWARF section data.

Link: https://lore.kernel.org/r/4d4bca1a0f869de020dac80d91f9acbf6df77eab.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