[ Upstream commit 10b4c4bce3f5541f54bcc2039720b11d2bc96d79 ]
If SAVE and RESTORE unwind hints are in different basic blocks, and
objtool sees the RESTORE before the SAVE, it errors out with:
vmlinux.o: warning: objtool: vmw_port_hb_in+0x242: objtool isn't smart enough to handle this CFI save/restore combo
In such a case, defer following the RESTORE block until the
straight-line path gets followed later.
Fixes: 8faea26e61 ("objtool: Re-add UNWIND_HINT_{SAVE_RESTORE}")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202402240702.zJFNmahW-lkp@intel.com/
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240227073527.avcm5naavbv3cj5s@treble
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e959c279d391c10b35ce300fb4b0fe3b98e86bd2 ]
If objtool runs into a problem that causes it to exit early, the overall
tool still returns a status code of 0, which causes the build to
continue as if nothing went wrong.
Note this only affects early errors, as later errors are still ignored
by check().
Fixes: b51277eb97 ("objtool: Ditch subcommands")
Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
Link: https://lore.kernel.org/r/cb6a28832d24b2ebfafd26da9abb95f874c83045.1696355111.git.aplattner@nvidia.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Cold functions and their non-cold counterparts can use _THIS_IP_ to
reference each other. Don't warn about !ENDBR in that case.
Note that for GCC this is currently irrelevant in light of the following
commit
c27cd083cf ("Compiler attributes: GCC cold function alignment workarounds")
which disabled cold functions in the kernel. However this may still be
possible with Clang.
Fixes several warnings like the following:
drivers/scsi/bnx2i/bnx2i.prelink.o: warning: objtool: bnx2i_hw_ep_disconnect+0x19d: relocation to !ENDBR: bnx2i_hw_ep_disconnect.cold+0x0
drivers/net/ipvlan/ipvlan.prelink.o: warning: objtool: ipvlan_addr4_event.cold+0x28: relocation to !ENDBR: ipvlan_addr4_event+0xda
drivers/net/ipvlan/ipvlan.prelink.o: warning: objtool: ipvlan_addr6_event.cold+0x26: relocation to !ENDBR: ipvlan_addr6_event+0xb7
drivers/net/ethernet/broadcom/tg3.prelink.o: warning: objtool: tg3_set_ringparam.cold+0x17: relocation to !ENDBR: tg3_set_ringparam+0x115
drivers/net/ethernet/broadcom/tg3.prelink.o: warning: objtool: tg3_self_test.cold+0x17: relocation to !ENDBR: tg3_self_test+0x2e1
drivers/target/iscsi/cxgbit/cxgbit.prelink.o: warning: objtool: __cxgbit_free_conn.cold+0x24: relocation to !ENDBR: __cxgbit_free_conn+0xfb
net/can/can.prelink.o: warning: objtool: can_rx_unregister.cold+0x2c: relocation to !ENDBR: can_rx_unregister+0x11b
drivers/net/ethernet/qlogic/qed/qed.prelink.o: warning: objtool: qed_spq_post+0xc0: relocation to !ENDBR: qed_spq_post.cold+0x9a
drivers/net/ethernet/qlogic/qed/qed.prelink.o: warning: objtool: qed_iwarp_ll2_comp_syn_pkt.cold+0x12f: relocation to !ENDBR: qed_iwarp_ll2_comp_syn_pkt+0x34b
net/tipc/tipc.prelink.o: warning: objtool: tipc_nametbl_publish.cold+0x21: relocation to !ENDBR: tipc_nametbl_publish+0xa6
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/d8f1ab6a23a6105bc023c132b105f245c7976be6.1694476559.git.jpoimboe@kernel.org
For stack-validation of a frame-pointer build, objtool validates that
every CALL instruction is preceded by a frame-setup. The new SRSO
return thunks violate this with their RSB stuffing trickery.
Extend the __fentry__ exception to also cover the embedded_insn case
used for this. This cures:
vmlinux.o: warning: objtool: srso_untrain_ret+0xd: call without frame pointer save/setup
Fixes: 4ae68b26c3 ("objtool/x86: Fix SRSO mess")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20230816115921.GH980931@hirez.programming.kicks-ass.net
Rename the original retbleed return thunk and untrain_ret to
retbleed_return_thunk() and retbleed_untrain_ret().
No functional changes.
Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230814121148.909378169@infradead.org
Use the existing configurable return thunk. There is absolute no
justification for having created this __x86_return_thunk alternative.
To clarify, the whole thing looks like:
Zen3/4 does:
srso_alias_untrain_ret:
nop2
lfence
jmp srso_alias_return_thunk
int3
srso_alias_safe_ret: // aliasses srso_alias_untrain_ret just so
add $8, %rsp
ret
int3
srso_alias_return_thunk:
call srso_alias_safe_ret
ud2
While Zen1/2 does:
srso_untrain_ret:
movabs $foo, %rax
lfence
call srso_safe_ret (jmp srso_return_thunk ?)
int3
srso_safe_ret: // embedded in movabs instruction
add $8,%rsp
ret
int3
srso_return_thunk:
call srso_safe_ret
ud2
While retbleed does:
zen_untrain_ret:
test $0xcc, %bl
lfence
jmp zen_return_thunk
int3
zen_return_thunk: // embedded in the test instruction
ret
int3
Where Zen1/2 flush the BTB entry using the instruction decoder trick
(test,movabs) Zen3/4 use BTB aliasing. SRSO adds a return sequence
(srso_safe_ret()) which forces the function return instruction to
speculate into a trap (UD2). This RET will then mispredict and
execution will continue at the return site read from the top of the
stack.
Pick one of three options at boot (evey function can only ever return
once).
[ bp: Fixup commit message uarch details and add them in a comment in
the code too. Add a comment about the srso_select_mitigation()
dependency on retbleed_select_mitigation(). Add moar ifdeffery for
32-bit builds. Add a dummy srso_untrain_ret_alias() definition for
32-bit alternatives needing the symbol. ]
Fixes: fb3bd914b3 ("x86/srso: Add a Speculative RAS Overflow mitigation")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230814121148.842775684@infradead.org
Objtool --rethunk does two things:
- it collects all (tail) call's of __x86_return_thunk and places them
into .return_sites. These are typically compiler generated, but
RET also emits this same.
- it fudges the validation of the __x86_return_thunk symbol; because
this symbol is inside another instruction, it can't actually find
the instruction pointed to by the symbol offset and gets upset.
Because these two things pertained to the same symbol, there was no
pressing need to separate these two separate things.
However, alas, along comes SRSO and more crazy things to deal with
appeared.
The SRSO patch itself added the following symbol names to identify as
rethunk:
'srso_untrain_ret', 'srso_safe_ret' and '__ret'
Where '__ret' is the old retbleed return thunk, 'srso_safe_ret' is a
new similarly embedded return thunk, and 'srso_untrain_ret' is
completely unrelated to anything the above does (and was only included
because of that INT3 vs UD2 issue fixed previous).
Clear things up by adding a second category for the embedded instruction
thing.
Fixes: fb3bd914b3 ("x86/srso: Add a Speculative RAS Overflow mitigation")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230814121148.704502245@infradead.org
The linker script arch/x86/kernel/vmlinux.lds.S matches the thunk
sections ".text.__x86.*" from arch/x86/lib/retpoline.S as follows:
.text {
[...]
TEXT_TEXT
[...]
__indirect_thunk_start = .;
*(.text.__x86.*)
__indirect_thunk_end = .;
[...]
}
Macro TEXT_TEXT references TEXT_MAIN which normally expands to only
".text". However, with CONFIG_LTO_CLANG, TEXT_MAIN becomes
".text .text.[0-9a-zA-Z_]*" which wrongly matches also the thunk
sections. The output layout is then different than expected. For
instance, the currently defined range [__indirect_thunk_start,
__indirect_thunk_end] becomes empty.
Prevent the problem by using ".." as the first separator, for example,
".text..__x86.indirect_thunk". This pattern is utilized by other
explicit section names which start with one of the standard prefixes,
such as ".text" or ".data", and that need to be individually selected in
the linker script.
[ nathan: Fix conflicts with SRSO and fold in fix issue brought up by
Andrew Cooper in post-review:
https://lore.kernel.org/20230803230323.1478869-1-andrew.cooper3@citrix.com ]
Fixes: dc5723b02e ("kbuild: add support for Clang LTO")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230711091952.27944-2-petr.pavlu@suse.com
Add a mitigation for the speculative return address stack overflow
vulnerability found on AMD processors.
The mitigation works by ensuring all RET instructions speculate to
a controlled location, similar to how speculation is controlled in the
retpoline sequence. To accomplish this, the __x86_return_thunk forces
the CPU to mispredict every function return using a 'safe return'
sequence.
To ensure the safety of this mitigation, the kernel must ensure that the
safe return sequence is itself free from attacker interference. In Zen3
and Zen4, this is accomplished by creating a BTB alias between the
untraining function srso_untrain_ret_alias() and the safe return
function srso_safe_ret_alias() which results in evicting a potentially
poisoned BTB entry and using that safe one for all function returns.
In older Zen1 and Zen2, this is accomplished using a reinterpretation
technique similar to Retbleed one: srso_untrain_ret() and
srso_safe_ret().
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
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: eb0481bbc4 ("objtool: Fix reloc_hash size")
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20230629102051.42E8360467@lion.mk-sys.cz
The objtool merge in commit 6f612579be ("Merge tag 'objtool-core ...")
generated a semantic conflict that was not resolved.
The btrfs_assertfail() entry was removed from the noreturn list in
commit b831306b3b ("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
6245ce4ab6 ("objtool: Move noreturn function list to separate file"),
and should be removed from that post-merge as well.
Do it explicitly.
Cc: David Sterba <dsterba@suse.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- 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
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
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
...
This KUnit update for Linux 6.5-rc1 consists of:
- 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.
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Merge tag 'linux-kselftest-kunit-6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest
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
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
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Merge tag 'x86_alternatives_for_v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
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
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] <TASK>
[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] <TASK>
[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 <jpoimboe@kernel.org>
Signed-off-by: David Sterba <dsterba@suse.com>
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 <jpoimboe@kernel.org>
When creating an annotation section, allocate the reloc section data at
the beginning. This simplifies the data model a bit and also saves
memory due to the removal of malloc() in elf_rebuild_reloc_section().
With allyesconfig + CONFIG_DEBUG_INFO:
- Before: peak heap memory consumption: 53.49G
- After: peak heap memory consumption: 49.02G
Link: https://lore.kernel.org/r/048e908f3ede9b66c15e44672b6dda992b1dae3e.1685464332.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
The GElf_Rel[a] structs have more similarities than differences. It's
safe to hard-code the assumptions about their shared fields as they will
never change. Consolidate their handling where possible, getting rid of
duplicated code.
Also, at least for now we only ever create rela sections, so simplify
the relocation creation code to be rela-only.
Link: https://lore.kernel.org/r/dcabf6df400ca500ea929f1e4284f5e5ec0b27c8.1685464332.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
- The term "reloc" is overloaded to mean both "an instance of struct
reloc" and "a reloc section". Change the latter to "rsec".
- For variable names, use "sec" for regular sections and "rsec" for rela
sections to prevent them getting mixed up.
- For struct reloc variables, use "reloc" instead of "rel" everywhere
for consistency.
Link: https://lore.kernel.org/r/8b790e403df46f445c21003e7893b8f53b99a6f3.1685464332.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
There are several places where warnings variables are not needed,
remove them and directly return 0.
Signed-off-by: Lu Hongfei <luhongfei@vivo.com>
Link: https://lore.kernel.org/r/20230530075649.21661-1-luhongfei@vivo.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This is a hack, but it works for now.
Problem is, exc_double_fault() may or may not return, depending on
whether CONFIG_X86_ESPFIX64 is set. But objtool has no visibility to
the kernel config.
"Fix" it by silencing the exc_double_fault() __noreturn warning.
This removes the following warning:
vmlinux.o: warning: objtool: xenpv_exc_double_fault+0xd: exc_double_fault() is missing a __noreturn annotation
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/a45b085071d3a7d049a20f9e78754452336ecbe8.1681853186.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Unreachable instruction warnings are limited to once per object file.
That no longer makes sense for vmlinux validation, which might have
more unreachable instructions lurking in other places. Change it to
once per function.
Note this affects some other (much rarer) non-fatal warnings as well.
In general I think one-warning-per-function makes sense, as related
warnings can accumulate quickly and we want to eventually get back to
failing the build with -Werror anyway.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/9d38f881bfc34e031c74e4e90064ccb3e49f599a.1681853186.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
A little while ago someone (Kirill) ran into the whole 'alternatives don't
do relocations nonsense' again and I got annoyed enough to actually look
at the code.
Since the whole alternative machinery already fully decodes the
instructions it is simple enough to adjust immediates and displacement
when needed. Specifically, the immediates for IP modifying instructions
(JMP, CALL, Jcc) and the displacement for RIP-relative instructions.
[ bp: Massage comment some more and get rid of third loop in
apply_relocation(). ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230208171431.313857925@infradead.org
- Mark arch_cpu_idle_dead() __noreturn, make all architectures & drivers that did
this inconsistently follow this new, common convention, and fix all the fallout
that objtool can now detect statically.
- Fix/improve the ORC unwinder becoming unreliable due to UNWIND_HINT_EMPTY ambiguity,
split it into UNWIND_HINT_END_OF_STACK and UNWIND_HINT_UNDEFINED to resolve it.
- Fix noinstr violations in the KCSAN code and the lkdtm/stackleak code.
- Generate ORC data for __pfx code
- Add more __noreturn annotations to various kernel startup/shutdown/panic functions.
- Misc improvements & fixes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar:
- Mark arch_cpu_idle_dead() __noreturn, make all architectures &
drivers that did this inconsistently follow this new, common
convention, and fix all the fallout that objtool can now detect
statically
- Fix/improve the ORC unwinder becoming unreliable due to
UNWIND_HINT_EMPTY ambiguity, split it into UNWIND_HINT_END_OF_STACK
and UNWIND_HINT_UNDEFINED to resolve it
- Fix noinstr violations in the KCSAN code and the lkdtm/stackleak code
- Generate ORC data for __pfx code
- Add more __noreturn annotations to various kernel startup/shutdown
and panic functions
- Misc improvements & fixes
* tag 'objtool-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits)
x86/hyperv: Mark hv_ghcb_terminate() as noreturn
scsi: message: fusion: Mark mpt_halt_firmware() __noreturn
x86/cpu: Mark {hlt,resume}_play_dead() __noreturn
btrfs: Mark btrfs_assertfail() __noreturn
objtool: Include weak functions in global_noreturns check
cpu: Mark nmi_panic_self_stop() __noreturn
cpu: Mark panic_smp_self_stop() __noreturn
arm64/cpu: Mark cpu_park_loop() and friends __noreturn
x86/head: Mark *_start_kernel() __noreturn
init: Mark start_kernel() __noreturn
init: Mark [arch_call_]rest_init() __noreturn
objtool: Generate ORC data for __pfx code
x86/linkage: Fix padding for typed functions
objtool: Separate prefix code from stack validation code
objtool: Remove superfluous dead_end_function() check
objtool: Add symbol iteration helpers
objtool: Add WARN_INSN()
scripts/objdump-func: Support multiple functions
context_tracking: Fix KCSAN noinstr violation
objtool: Add stackleak instrumentation to uaccess safe list
...
Josh Poimboeuf