Recent commit:
020126239b Revert "x86/orc: Make it callthunk aware"
Made the only user of is_callthunk() depend on CONFIG_BPF_JIT=y, while
the definition of the helper function is unconditional.
Move is_callthunk() inside the #ifdef block.
Addresses this build failure:
arch/x86/kernel/callthunks.c:296:13: error: ‘is_callthunk’ defined but not used [-Werror=unused-function]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
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>
VMware high-bandwidth hypercalls take the RBP register as input. This
breaks basic frame pointer convention, as RBP should never be clobbered.
So frame pointer unwinding is broken for the instructions surrounding
the hypercalls. Fortunately this doesn't break live patching with
CONFIG_FRAME_POINTER, as it only unwinds from blocking tasks, and stack
traces from preempted tasks are already marked unreliable anyway.
However, for live patching with ORC, this could actually be a
theoretical problem if vmw_port_hb_{in,out}() were still compiled with a
frame pointer due to having an aligned stack. In practice that hasn't
seemed to be an issue since the objtool warnings have only been seen
with CONFIG_FRAME_POINTER.
Add unwind hint annotations to tell the ORC unwinder to mark stack
traces as unreliable.
Fixes the following warnings:
vmlinux.o: warning: objtool: vmw_port_hb_in+0x1df: return with modified stack frame
vmlinux.o: warning: objtool: vmw_port_hb_out+0x1dd: return with modified stack frame
Fixes: 89da76fde6 ("drm/vmwgfx: Add VMWare host messaging capability")
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202305160135.97q0Elax-lkp@intel.com/
Link: https://lore.kernel.org/r/4c795f2d87bc0391cf6543bcb224fa540b55ce4b.1685981486.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Commit 396e0b8e09 ("x86/orc: Make it callthunk aware") attempted to
deal with the fact that function prefix code didn't have ORC coverage.
However, it didn't work as advertised. Use of the "null" ORC entry just
caused affected unwinds to end early.
The root cause has now been fixed with commit 5743654f5e ("objtool:
Generate ORC data for __pfx code").
Revert most of commit 396e0b8e09 ("x86/orc: Make it callthunk aware").
The is_callthunk() function remains as it's now used by other code.
Link: https://lore.kernel.org/r/a05b916ef941da872cbece1ab3593eceabd05a79.1684245404.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
For certain configs objtool will complain like:
vmlinux.o: warning: objtool: lkdtm_UNSET_SMEP+0x1c3: relocation to !ENDBR: native_write_cr4+0x41
What happens is that GCC optimizes the loop:
insn = (unsigned char *)native_write_cr4;
for (i = 0; i < MOV_CR4_DEPTH; i++)
to read something like:
for (insn = (unsigned char *)native_write_cr4;
insn < (unsigned char *)native_write_cr4 + MOV_CR4_DEPTH;
insn++)
Which then obviously generates the text reference
native_write_cr4+041. Since none of this is a fast path, simply
confuse GCC enough to inhibit this optimization.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/Y3JdgbXRV0MNZ+9h@hirez.programming.kicks-ass.net
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>
prevent_tail_call_optimization() was added in
commit a9a3ed1eff ("x86: Fix early boot crash on gcc-10, third try")
to work around stack canaries getting inserted into functions that would
initialize the stack canary in the first place.
Now that we have no_stack_protector function attribute (gcc-11+,
clang-7+) and use it on start_kernel(), remove the call to
prevent_tail_call_optimization() such that we may one day remove it
outright.
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20230412-no_stackp-v2-2-116f9fe4bbe7@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Pull compute express link fixes from Dan Williams:
- Fix a compilation issue with DEFINE_STATIC_SRCU() in the unit tests
- Fix leaking kernel memory to a root-only sysfs attribute
* tag 'cxl-fixes-6.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl:
cxl: Add missing return to cdat read error path
tools/testing/cxl: Use DEFINE_STATIC_SRCU()
Pull parisc architecture fixes from Helge Deller:
- Fix encoding of swp_entry due to added SWP_EXCLUSIVE flag
- Include reboot.h to avoid gcc-12 compiler warning
* tag 'parisc-for-6.4-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
parisc: Fix encoding of swp_entry due to added SWP_EXCLUSIVE flag
parisc: kexec: include reboot.h
Pull ARM fixes from Russell King:
- fix unwinder for uleb128 case
- fix kernel-doc warnings for HP Jornada 7xx
- fix unbalanced stack on vfp success path
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
ARM: 9297/1: vfp: avoid unbalanced stack on 'success' return path
ARM: 9296/1: HP Jornada 7XX: fix kernel-doc warnings
ARM: 9295/1: unwind:fix unwind abort for uleb128 case
Pull locking fix from Borislav Petkov:
- Make sure __down_read_common() is always inlined so that the callers'
names land in traceevents output and thus the blocked function can be
identified
* tag 'locking_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/rwsem: Add __always_inline annotation to __down_read_common() and inlined callers
Pull perf fixes from Borislav Petkov:
- Make sure the PEBS buffer is flushed before reprogramming the
hardware so that the correct record sizes are used
- Update the sample size for AMD BRS events
- Fix a confusion with using the same on-stack struct with different
events in the event processing path
* tag 'perf_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel/ds: Flush PEBS DS when changing PEBS_DATA_CFG
perf/x86: Fix missing sample size update on AMD BRS
perf/core: Fix perf_sample_data not properly initialized for different swevents in perf_tp_event()
Pull scheduler fix from Borislav Petkov:
- Fix a couple of kernel-doc warnings
* tag 'sched_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: fix cid_lock kernel-doc warnings
Pull x86 fix from Borislav Petkov:
- Add the required PCI IDs so that the generic SMN accesses provided by
amd_nb.c work for drivers which switch to them. Add a PCI device ID
to k10temp's table so that latter is loaded on such systems too
* tag 'x86_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
hwmon: (k10temp) Add PCI ID for family 19, model 78h
x86/amd_nb: Add PCI ID for family 19h model 78h
