On GCC 12, the build fails due to a possible truncated string:
check.c: In function 'validate_call':
check.c:2865:58: error: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 9 [-Werror=format-truncation=]
2865 | snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
| ^~
In theory it's a valid bug:
static char pvname[16];
int idx;
...
idx = (rel->addend / sizeof(void *));
snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
There are only 7 chars for %d while it could take up to 9, so the
printed "pv_ops[%d]" string could get truncated.
In reality the bug should never happen, because pv_ops only has ~80
entries, so 7 chars for the integer is more than enough. Still, it's
worth fixing. Bump the buffer size by 2 bytes to silence the warning.
[ jpoimboe: changed size to 19; massaged changelog ]
Fixes: db2b0c5d7b ("objtool: Support pv_opsindirect calls for noinstr")
Reported-by: Adam Borowski <kilobyte@angband.pl>
Reported-by: Martin Liška <mliska@suse.cz>
Signed-off-by: Sergei Trofimovich <slyich@gmail.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220120233748.2062559-1-slyich@gmail.com
Pull signal/exit/ptrace updates from Eric Biederman:
"This set of changes deletes some dead code, makes a lot of cleanups
which hopefully make the code easier to follow, and fixes bugs found
along the way.
The end-game which I have not yet reached yet is for fatal signals
that generate coredumps to be short-circuit deliverable from
complete_signal, for force_siginfo_to_task not to require changing
userspace configured signal delivery state, and for the ptrace stops
to always happen in locations where we can guarantee on all
architectures that the all of the registers are saved and available on
the stack.
Removal of profile_task_ext, profile_munmap, and profile_handoff_task
are the big successes for dead code removal this round.
A bunch of small bug fixes are included, as most of the issues
reported were small enough that they would not affect bisection so I
simply added the fixes and did not fold the fixes into the changes
they were fixing.
There was a bug that broke coredumps piped to systemd-coredump. I
dropped the change that caused that bug and replaced it entirely with
something much more restrained. Unfortunately that required some
rebasing.
Some successes after this set of changes: There are few enough calls
to do_exit to audit in a reasonable amount of time. The lifetime of
struct kthread now matches the lifetime of struct task, and the
pointer to struct kthread is no longer stored in set_child_tid. The
flag SIGNAL_GROUP_COREDUMP is removed. The field group_exit_task is
removed. Issues where task->exit_code was examined with
signal->group_exit_code should been examined were fixed.
There are several loosely related changes included because I am
cleaning up and if I don't include them they will probably get lost.
The original postings of these changes can be found at:
https://lkml.kernel.org/r/87a6ha4zsd.fsf@email.froward.int.ebiederm.orghttps://lkml.kernel.org/r/87bl1kunjj.fsf@email.froward.int.ebiederm.orghttps://lkml.kernel.org/r/87r19opkx1.fsf_-_@email.froward.int.ebiederm.org
I trimmed back the last set of changes to only the obviously correct
once. Simply because there was less time for review than I had hoped"
* 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (44 commits)
ptrace/m68k: Stop open coding ptrace_report_syscall
ptrace: Remove unused regs argument from ptrace_report_syscall
ptrace: Remove second setting of PT_SEIZED in ptrace_attach
taskstats: Cleanup the use of task->exit_code
exit: Use the correct exit_code in /proc/<pid>/stat
exit: Fix the exit_code for wait_task_zombie
exit: Coredumps reach do_group_exit
exit: Remove profile_handoff_task
exit: Remove profile_task_exit & profile_munmap
signal: clean up kernel-doc comments
signal: Remove the helper signal_group_exit
signal: Rename group_exit_task group_exec_task
coredump: Stop setting signal->group_exit_task
signal: Remove SIGNAL_GROUP_COREDUMP
signal: During coredumps set SIGNAL_GROUP_EXIT in zap_process
signal: Make coredump handling explicit in complete_signal
signal: Have prepare_signal detect coredumps using signal->core_state
signal: Have the oom killer detect coredumps using signal->core_state
exit: Move force_uaccess back into do_exit
exit: Guarantee make_task_dead leaks the tsk when calling do_task_exit
...
misleading/wrong stacktraces and confuse RELIABLE_STACKTRACE and
LIVEPATCH as the backtrace misses the function which is being fixed up.
- Add Straight Light Speculation mitigation support which uses a new
compiler switch -mharden-sls= which sticks an INT3 after a RET or an
indirect branch in order to block speculation after them. Reportedly,
CPUs do speculate behind such insns.
- The usual set of cleanups and improvements
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Merge tag 'x86_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 core updates from Borislav Petkov:
- Get rid of all the .fixup sections because this generates
misleading/wrong stacktraces and confuse RELIABLE_STACKTRACE and
LIVEPATCH as the backtrace misses the function which is being fixed
up.
- Add Straight Line Speculation mitigation support which uses a new
compiler switch -mharden-sls= which sticks an INT3 after a RET or an
indirect branch in order to block speculation after them. Reportedly,
CPUs do speculate behind such insns.
- The usual set of cleanups and improvements
* tag 'x86_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
x86/entry_32: Fix segment exceptions
objtool: Remove .fixup handling
x86: Remove .fixup section
x86/word-at-a-time: Remove .fixup usage
x86/usercopy: Remove .fixup usage
x86/usercopy_32: Simplify __copy_user_intel_nocache()
x86/sgx: Remove .fixup usage
x86/checksum_32: Remove .fixup usage
x86/vmx: Remove .fixup usage
x86/kvm: Remove .fixup usage
x86/segment: Remove .fixup usage
x86/fpu: Remove .fixup usage
x86/xen: Remove .fixup usage
x86/uaccess: Remove .fixup usage
x86/futex: Remove .fixup usage
x86/msr: Remove .fixup usage
x86/extable: Extend extable functionality
x86/entry_32: Remove .fixup usage
x86/entry_64: Remove .fixup usage
x86/copy_mc_64: Remove .fixup usage
...
Recently the kbuild robot reported two new errors:
>> lib/kunit/kunit-example-test.o: warning: objtool: .text.unlikely: unexpected end of section
>> arch/x86/kernel/dumpstack.o: warning: objtool: oops_end() falls through to next function show_opcodes()
I don't know why they did not occur in my test setup but after digging
it I realized I had accidentally dropped a comma in
tools/objtool/check.c when I renamed rewind_stack_do_exit to
rewind_stack_and_make_dead.
Add that comma back to fix objtool errors.
Link: https://lkml.kernel.org/r/202112140949.Uq5sFKR1-lkp@intel.com
Fixes: 0e25498f8c ("exit: Add and use make_task_dead.")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Update complete_and_exit to call kthread_exit instead of do_exit.
Change the name to reflect this change in functionality. All of the
users of complete_and_exit are causing the current kthread to exit so
this change makes it clear what is happening.
Move the implementation of kthread_complete_and_exit from
kernel/exit.c to to kernel/kthread.c. As this function is kthread
specific it makes most sense to live with the kthread functions.
There are no functional change.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Update module_put_and_exit to call kthread_exit instead of do_exit.
Change the name to reflect this change in functionality. All of the
users of module_put_and_exit are causing the current kthread to exit
so this change makes it clear what is happening. There is no
functional change.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
The way the per task_struct exit_code is used by kernel threads is not
quite compatible how it is used by userspace applications. The low
byte of the userspace exit_code value encodes the exit signal. While
kthreads just use the value as an int holding ordinary kernel function
exit status like -EPERM.
Add kthread_exit to clearly separate the two kinds of uses.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
There are two big uses of do_exit. The first is it's design use to be
the guts of the exit(2) system call. The second use is to terminate
a task after something catastrophic has happened like a NULL pointer
in kernel code.
Add a function make_task_dead that is initialy exactly the same as
do_exit to cover the cases where do_exit is called to handle
catastrophic failure. In time this can probably be reduced to just a
light wrapper around do_task_dead. For now keep it exactly the same so
that there will be no behavioral differences introducing this new
concept.
Replace all of the uses of do_exit that use it for catastraphic
task cleanup with make_task_dead to make it clear what the code
is doing.
As part of this rename rewind_stack_do_exit
rewind_stack_and_make_dead.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Teach objtool to turn instrumentation required for memory barrier
modeling into nops in noinstr text.
The __tsan_func_entry/exit calls are still emitted by compilers even
with the __no_sanitize_thread attribute. The memory barrier
instrumentation will be inserted explicitly (without compiler help), and
thus needs to also explicitly be removed.
Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Adds KCSAN's memory barrier instrumentation to objtool's uaccess
whitelist.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Teach objtool to validate the straight-line-speculation constraints:
- speculation trap after indirect calls
- speculation trap after RET
Notable: when an instruction is annotated RETPOLINE_SAFE, indicating
speculation isn't a problem, also don't care about sls for that
instruction.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211204134908.023037659@infradead.org
Add a few signature bytes after the static call trampoline and verify
those bytes match before patching the trampoline. This avoids patching
random other JMPs (such as CFI jump-table entries) instead.
These bytes decode as:
d: 53 push %rbx
e: 43 54 rex.XB push %r12
And happen to spell "SCT".
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20211030074758.GT174703@worktop.programming.kicks-ass.net
- kprobes: Restructured stack unwinder to show properly on x86 when a stack
dump happens from a kretprobe callback.
- Fix to bootconfig parsing
- Have tracefs allow owner and group permissions by default (only denying
others). There's been pressure to allow non root to tracefs in a
controlled fashion, and using groups is probably the safest.
- Bootconfig memory managament updates.
- Bootconfig clean up to have the tools directory be less dependent on
changes in the kernel tree.
- Allow perf to be traced by function tracer.
- Rewrite of function graph tracer to be a callback from the function tracer
instead of having its own trampoline (this change will happen on an arch
by arch basis, and currently only x86_64 implements it).
- Allow multiple direct trampolines (bpf hooks to functions) be batched
together in one synchronization.
- Allow histogram triggers to add variables that can perform calculations
against the event's fields.
- Use the linker to determine architecture callbacks from the ftrace
trampoline to allow for proper parameter prototypes and prevent warnings
from the compiler.
- Extend histogram triggers to key off of variables.
- Have trace recursion use bit magic to determine preempt context over if
branches.
- Have trace recursion disable preemption as all use cases do anyway.
- Added testing for verification of tracing utilities.
- Various small clean ups and fixes.
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Merge tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
- kprobes: Restructured stack unwinder to show properly on x86 when a
stack dump happens from a kretprobe callback.
- Fix to bootconfig parsing
- Have tracefs allow owner and group permissions by default (only
denying others). There's been pressure to allow non root to tracefs
in a controlled fashion, and using groups is probably the safest.
- Bootconfig memory managament updates.
- Bootconfig clean up to have the tools directory be less dependent on
changes in the kernel tree.
- Allow perf to be traced by function tracer.
- Rewrite of function graph tracer to be a callback from the function
tracer instead of having its own trampoline (this change will happen
on an arch by arch basis, and currently only x86_64 implements it).
- Allow multiple direct trampolines (bpf hooks to functions) be batched
together in one synchronization.
- Allow histogram triggers to add variables that can perform
calculations against the event's fields.
- Use the linker to determine architecture callbacks from the ftrace
trampoline to allow for proper parameter prototypes and prevent
warnings from the compiler.
- Extend histogram triggers to key off of variables.
- Have trace recursion use bit magic to determine preempt context over
if branches.
- Have trace recursion disable preemption as all use cases do anyway.
- Added testing for verification of tracing utilities.
- Various small clean ups and fixes.
* tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (101 commits)
tracing/histogram: Fix semicolon.cocci warnings
tracing/histogram: Fix documentation inline emphasis warning
tracing: Increase PERF_MAX_TRACE_SIZE to handle Sentinel1 and docker together
tracing: Show size of requested perf buffer
bootconfig: Initialize ret in xbc_parse_tree()
ftrace: do CPU checking after preemption disabled
ftrace: disable preemption when recursion locked
tracing/histogram: Document expression arithmetic and constants
tracing/histogram: Optimize division by a power of 2
tracing/histogram: Covert expr to const if both operands are constants
tracing/histogram: Simplify handling of .sym-offset in expressions
tracing: Fix operator precedence for hist triggers expression
tracing: Add division and multiplication support for hist triggers
tracing: Add support for creating hist trigger variables from literal
selftests/ftrace: Stop tracing while reading the trace file by default
MAINTAINERS: Update KPROBES and TRACING entries
test_kprobes: Move it from kernel/ to lib/
docs, kprobes: Remove invalid URL and add new reference
samples/kretprobes: Fix return value if register_kretprobe() failed
lib/bootconfig: Fix the xbc_get_info kerneldoc
...
Instead of writing complete alternatives, simply provide a list of all
the retpoline thunk calls. Then the kernel is free to do with them as
it pleases. Simpler code all-round.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120309.850007165@infradead.org
Any one instruction can only ever call a single function, therefore
insn->mcount_loc_node is superfluous and can use insn->call_node.
This shrinks struct instruction, which is by far the most numerous
structure objtool creates.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120309.785456706@infradead.org
Assume ALTERNATIVE()s know what they're doing and do not change, or
cause to change, instructions in .altinstr_replacement sections.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120309.722511775@infradead.org
In order to avoid calling str*cmp() on symbol names, over and over, do
them all once upfront and store the result.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120309.658539311@infradead.org
The section structure already contains sh_size, so just remove the extra
'len' member that requires extra mirroring and potential confusion.
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20210822225037.54620-3-joe.lawrence@redhat.com
Cc: Andy Lavr <andy.lavr@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
If a function is ignored, also ignore its hints. This is useful for the
case where the function ignore is conditional on frame pointers, e.g.
STACK_FRAME_NON_STANDARD_FP().
Link: https://lkml.kernel.org/r/163163048317.489837.10988954983369863209.stgit@devnote2
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Normally objtool will now follow indirect calls; there is no need.
However, this becomes a problem with noinstr validation; if there's an
indirect call from noinstr code, we very much need to know it is to
another noinstr function. Luckily there aren't many indirect calls in
entry code with the obvious exception of paravirt. As such, noinstr
validation didn't work with paravirt kernels.
In order to track pv_ops[] call targets, objtool reads the static
pv_ops[] tables as well as direct assignments to the pv_ops[] array,
provided the compiler makes them a single instruction like:
bf87: 48 c7 05 00 00 00 00 00 00 00 00 movq $0x0,0x0(%rip)
bf92 <xen_init_spinlocks+0x5f>
bf8a: R_X86_64_PC32 pv_ops+0x268
There are, as of yet, no warnings for when this goes wrong :/
Using the functions found with the above means, all pv_ops[] calls are
now subject to noinstr validation.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210624095149.118815755@infradead.org
Turns out the compilers also generate tail calls to __sanitize_cov*(),
make sure to also patch those out in noinstr code.
Fixes: 0f1441b44e ("objtool: Fix noinstr vs KCOV")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20210624095147.818783799@infradead.org
Andi reported that objtool on vmlinux.o consumes more memory than his
system has, leading to horrific performance.
This is in part because we keep a struct instruction for every
instruction in the file in-memory. Shrink struct instruction by
removing the CFI state (which includes full register state) from it
and demand allocating it.
Given most instructions don't actually change CFI state, there's lots
of repetition there, so add a hash table to find previous CFI
instances.
Reduces memory consumption (and runtime) for processing an
x86_64-allyesconfig:
pre: 4:40.84 real, 143.99 user, 44.18 sys, 30624988 mem
post: 2:14.61 real, 108.58 user, 25.04 sys, 16396184 mem
Suggested-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210624095147.756759107@infradead.org
The asm_cpu_bringup_and_idle() function is required to push the return
value on the stack in order to make ORC happy, but the only reason
objtool doesn't complain is because of a happy accident.
The thing is that asm_cpu_bringup_and_idle() doesn't return, so
validate_branch() never terminates and falls through to the next
function, which in the normal case is the hypercall_page. And that, as
it happens, is 4095 NOPs and a RET.
Make asm_cpu_bringup_and_idle() terminate on it's own, by making the
function it calls as a dead-end. This way we no longer rely on what
code happens to come after.
Fixes: c3881eb58d ("x86/xen: Make the secondary CPU idle tasks reliable")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/20210624095147.693801717@infradead.org
Miroslav figured the code flow in handle_jump_alt() was sub-optimal
with that goto. Reflow the code to make it clearer.
Reported-by: Miroslav Benes <mbenes@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/YJ00lgslY+IpA/rL@hirez.programming.kicks-ass.net
When a jump_entry::key has bit1 set, rewrite the instruction to be a
NOP. This allows the compiler/assembler to emit JMP (and thus decide
on which encoding to use).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194158.091028792@infradead.org
- Standardize the crypto asm code so that it looks like compiler-generated
code to objtool - so that it can understand it. This enables unwinding
from crypto asm code - and also fixes the last known remaining objtool
warnings for LTO and more.
- x86 decoder fixes: clean up and fix the decoder, and also extend it a bit
- Misc fixes and cleanups
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar:
- Standardize the crypto asm code so that it looks like compiler-
generated code to objtool - so that it can understand it. This
enables unwinding from crypto asm code - and also fixes the last
known remaining objtool warnings for LTO and more.
- x86 decoder fixes: clean up and fix the decoder, and also extend it a
bit
- Misc fixes and cleanups
* tag 'objtool-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
x86/crypto: Enable objtool in crypto code
x86/crypto/sha512-ssse3: Standardize stack alignment prologue
x86/crypto/sha512-avx2: Standardize stack alignment prologue
x86/crypto/sha512-avx: Standardize stack alignment prologue
x86/crypto/sha256-avx2: Standardize stack alignment prologue
x86/crypto/sha1_avx2: Standardize stack alignment prologue
x86/crypto/sha_ni: Standardize stack alignment prologue
x86/crypto/crc32c-pcl-intel: Standardize jump table
x86/crypto/camellia-aesni-avx2: Unconditionally allocate stack buffer
x86/crypto/aesni-intel_avx: Standardize stack alignment prologue
x86/crypto/aesni-intel_avx: Fix register usage comments
x86/crypto/aesni-intel_avx: Remove unused macros
objtool: Support asm jump tables
objtool: Parse options from OBJTOOL_ARGS
objtool: Collate parse_options() users
objtool: Add --backup
objtool,x86: More ModRM sugar
objtool,x86: Rewrite ADD/SUB/AND
objtool,x86: Support %riz encodings
objtool,x86: Simplify register decode
...
Objtool detection of asm jump tables would normally just work, except
for the fact that asm retpolines use alternatives. Objtool thinks the
alternative code path (a jump to the retpoline) is a sibling call.
Don't treat alternative indirect branches as sibling calls when the
original instruction has a jump table.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Link: https://lore.kernel.org/r/460cf4dc675d64e1124146562cabd2c05aa322e8.1614182415.git.jpoimboe@redhat.com
Track the reloc of instructions in the new instruction->reloc field
to avoid having to look them up again later.
( Technically x86 instructions can have two relocations, but not jumps
and calls, for which we're using this. )
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.195441549@infradead.org
Provide infrastructure for architectures to rewrite/augment compiler
generated retpoline calls. Similar to what we do for static_call()s,
keep track of the instructions that are retpoline calls.
Use the same list_head, since a retpoline call cannot also be a
static_call.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.130805730@infradead.org
We have 4 instances of adding a relocation. Create a common helper
to avoid growing even more.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.817438847@infradead.org
Instead of manually calling elf_rebuild_reloc_section() on sections
we've called elf_add_reloc() on, have elf_write() DTRT.
This makes it easier to add random relocations in places without
carefully tracking when we're done and need to flush what section.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.754213408@infradead.org
Currently, objtool generates tail call entries in add_jump_destination()
but waits until validate_branch() to generate the regular call entries.
Move these to add_call_destination() for consistency.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.691529901@infradead.org
The __x86_indirect_ naming is obviously not generic. Shorten to allow
matching some additional magic names later.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.630296706@infradead.org
Just like JMP handling, convert a direct CALL to a retpoline thunk
into a retpoline safe indirect CALL.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.567568238@infradead.org
Due to:
c9c324dc22 ("objtool: Support stack layout changes in alternatives")
it is now possible to simplify the retpolines.
Currently our retpolines consist of 2 symbols:
- __x86_indirect_thunk_\reg: the compiler target
- __x86_retpoline_\reg: the actual retpoline.
Both are consecutive in code and aligned such that for any one register
they both live in the same cacheline:
0000000000000000 <__x86_indirect_thunk_rax>:
0: ff e0 jmpq *%rax
2: 90 nop
3: 90 nop
4: 90 nop
0000000000000005 <__x86_retpoline_rax>:
5: e8 07 00 00 00 callq 11 <__x86_retpoline_rax+0xc>
a: f3 90 pause
c: 0f ae e8 lfence
f: eb f9 jmp a <__x86_retpoline_rax+0x5>
11: 48 89 04 24 mov %rax,(%rsp)
15: c3 retq
16: 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:0x0(%rax,%rax,1)
The thunk is an alternative_2, where one option is a JMP to the
retpoline. This was done so that objtool didn't need to deal with
alternatives with stack ops. But that problem has been solved, so now
it is possible to fold the entire retpoline into the alternative to
simplify and consolidate unused bytes:
0000000000000000 <__x86_indirect_thunk_rax>:
0: ff e0 jmpq *%rax
2: 90 nop
3: 90 nop
4: 90 nop
5: 90 nop
6: 90 nop
7: 90 nop
8: 90 nop
9: 90 nop
a: 90 nop
b: 90 nop
c: 90 nop
d: 90 nop
e: 90 nop
f: 90 nop
10: 90 nop
11: 66 66 2e 0f 1f 84 00 00 00 00 00 data16 nopw %cs:0x0(%rax,%rax,1)
1c: 0f 1f 40 00 nopl 0x0(%rax)
Notice that since the longest alternative sequence is now:
0: e8 07 00 00 00 callq c <.altinstr_replacement+0xc>
5: f3 90 pause
7: 0f ae e8 lfence
a: eb f9 jmp 5 <.altinstr_replacement+0x5>
c: 48 89 04 24 mov %rax,(%rsp)
10: c3 retq
17 bytes, we have 15 bytes NOP at the end of our 32 byte slot. (IOW, if
we can shrink the retpoline by 1 byte we can pack it more densely).
[ bp: Massage commit message. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210326151259.506071949@infradead.org
Commit ab234a260b ("x86/pv: Rework arch_local_irq_restore() to not
use popf") replaced "push %reg; popf" with something like: "test
$0x200, %reg; jz 1f; sti; 1:", which breaks the pushf/popf symmetry
that commit ea24213d80 ("objtool: Add UACCESS validation") relies
on.
The result is:
drivers/gpu/drm/amd/amdgpu/si.o: warning: objtool: si_common_hw_init()+0xf36: PUSHF stack exhausted
Meanwhile, commit c9c324dc22 ("objtool: Support stack layout changes
in alternatives") makes that we can actually use stack-ops in
alternatives, which means we can revert 1ff865e343 ("x86,smap: Fix
smap_{save,restore}() alternatives").
That in turn means we can limit the PUSHF/POPF handling of
ea24213d80 to those instructions that are in alternatives.
Fixes: ab234a260b ("x86/pv: Rework arch_local_irq_restore() to not use popf")
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/YEY4rIbQYa5fnnEp@hirez.programming.kicks-ass.net
Since we can now have multiple stack-ops per instruction, we don't
need to special case LEAVE and can simply emit the composite
operations.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/20210211173627.253273977@infradead.org
rewind_stack_do_exit()
UNWIND_HINT_FUNC
/* Prevent any naive code from trying to unwind to our caller. */
xorl %ebp, %ebp
movq PER_CPU_VAR(cpu_current_top_of_stack), %rax
leaq -PTREGS_SIZE(%rax), %rsp
UNWIND_HINT_REGS
call do_exit
Does unspeakable things to the stack, which objtool currently fails to
detect due to a limitation in instruction decoding. This will be
rectified after which the above will result in:
arch/x86/entry/entry_64.o: warning: objtool: .text+0xab: unsupported stack register modification
Allow the UNWIND_HINT on the next instruction to suppress this, it
will overwrite the state anyway.
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/20210211173626.918498579@infradead.org
The irq stack switching was moved out of the ASM entry code in course of
the entry code consolidation. It ended up being suboptimal in various
ways.
- Make the stack switching inline so the stackpointer manipulation is not
longer at an easy to find place.
- Get rid of the unnecessary indirect call.
- Avoid the double stack switching in interrupt return and reuse the
interrupt stack for softirq handling.
- A objtool fix for CONFIG_FRAME_POINTER=y builds where it got confused
about the stack pointer manipulation.
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Merge tag 'x86-entry-2021-02-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 irq entry updates from Thomas Gleixner:
"The irq stack switching was moved out of the ASM entry code in course
of the entry code consolidation. It ended up being suboptimal in
various ways.
This reworks the X86 irq stack handling:
- Make the stack switching inline so the stackpointer manipulation is
not longer at an easy to find place.
- Get rid of the unnecessary indirect call.
- Avoid the double stack switching in interrupt return and reuse the
interrupt stack for softirq handling.
- A objtool fix for CONFIG_FRAME_POINTER=y builds where it got
confused about the stack pointer manipulation"
* tag 'x86-entry-2021-02-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix stack-swizzle for FRAME_POINTER=y
um: Enforce the usage of asm-generic/softirq_stack.h
x86/softirq/64: Inline do_softirq_own_stack()
softirq: Move do_softirq_own_stack() to generic asm header
softirq: Move __ARCH_HAS_DO_SOFTIRQ to Kconfig
x86: Select CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
x86/softirq: Remove indirection in do_softirq_own_stack()
x86/entry: Use run_sysvec_on_irqstack_cond() for XEN upcall
x86/entry: Convert device interrupts to inline stack switching
x86/entry: Convert system vectors to irq stack macro
x86/irq: Provide macro for inlining irq stack switching
x86/apic: Split out spurious handling code
x86/irq/64: Adjust the per CPU irq stack pointer by 8
x86/irq: Sanitize irq stack tracking
x86/entry: Fix instrumentation annotation
Patch series "kasan: HW_TAGS tests support and fixes", v4.
This patchset adds support for running KASAN-KUnit tests with the
hardware tag-based mode and also contains a few fixes.
This patch (of 15):
There's a number of internal KASAN functions that are used across multiple
source code files and therefore aren't marked as static inline. To avoid
littering the kernel function names list with generic function names,
prefix all such KASAN functions with kasan_.
As a part of this change:
- Rename internal (un)poison_range() to kasan_(un)poison() (no _range)
to avoid name collision with a public kasan_unpoison_range().
- Rename check_memory_region() to kasan_check_range(), as it's a more
fitting name.
Link: https://lkml.kernel.org/r/cover.1610733117.git.andreyknvl@google.com
Link: https://linux-review.googlesource.com/id/I719cc93483d4ba288a634dba80ee6b7f2809cd26
Link: https://lkml.kernel.org/r/13777aedf8d3ebbf35891136e1f2287e2f34aaba.1610733117.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Suggested-by: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Generate __mcount_loc in objtool (Peter Zijlstra)
- Support running objtool against vmlinux.o (Sami Tolvanen)
- Clang LTO enablement for x86 (Sami Tolvanen)
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Merge tag 'clang-lto-v5.12-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull more clang LTO updates from Kees Cook:
"Clang LTO x86 enablement.
Full disclosure: while this has _not_ been in linux-next (since it
initially looked like the objtool dependencies weren't going to make
v5.12), it has been under daily build and runtime testing by Sami for
quite some time. These x86 portions have been discussed on lkml, with
Peter, Josh, and others helping nail things down.
The bulk of the changes are to get objtool working happily. The rest
of the x86 enablement is very small.
Summary:
- Generate __mcount_loc in objtool (Peter Zijlstra)
- Support running objtool against vmlinux.o (Sami Tolvanen)
- Clang LTO enablement for x86 (Sami Tolvanen)"
Link: https://lore.kernel.org/lkml/20201013003203.4168817-26-samitolvanen@google.com/
Link: https://lore.kernel.org/lkml/cover.1611263461.git.jpoimboe@redhat.com/
* tag 'clang-lto-v5.12-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
kbuild: lto: force rebuilds when switching CONFIG_LTO
x86, build: allow LTO to be selected
x86, cpu: disable LTO for cpu.c
x86, vdso: disable LTO only for vDSO
kbuild: lto: postpone objtool
objtool: Split noinstr validation from --vmlinux
x86, build: use objtool mcount
tracing: add support for objtool mcount
objtool: Don't autodetect vmlinux.o
objtool: Fix __mcount_loc generation with Clang's assembler
objtool: Add a pass for generating __mcount_loc
This change adds a --noinstr flag to objtool to allow us to specify
that we're processing vmlinux.o without also enabling noinstr
validation. This is needed to avoid false positives with LTO when we
run objtool on vmlinux.o without CONFIG_DEBUG_ENTRY.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
When objtool generates relocations for the __mcount_loc section, it
tries to reference __fentry__ calls by their section symbol offset.
However, this fails with Clang's integrated assembler as it may not
generate section symbols for every section. This patch looks up a
function symbol instead if the section symbol is missing, similarly
to commit e81e072443 ("objtool: Support Clang non-section symbols
in ORC generation").
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Add the --mcount option for generating __mcount_loc sections
needed for dynamic ftrace. Using this pass requires the kernel to
be compiled with -mfentry and CC_USING_NOP_MCOUNT to be defined
in Makefile.
Link: https://lore.kernel.org/lkml/20200625200235.GQ4781@hirez.programming.kicks-ass.net/
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
[Sami: rebased, dropped config changes, fixed to actually use --mcount,
and wrote a commit message.]
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
- Make objtool work for big-endian cross compiles
- Make stack tracking via stack pointer memory operations match push/pop
semantics to prepare for architectures w/o PUSH/POP instructions.
- Add support for analyzing alternatives
- Improve retpoline detection and handling
- Improve assembly code coverage on x86
- Provide support for inlined stack switching
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Merge tag 'objtool-core-2021-02-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Thomas Gleixner:
- Make objtool work for big-endian cross compiles
- Make stack tracking via stack pointer memory operations match
push/pop semantics to prepare for architectures w/o PUSH/POP
instructions.
- Add support for analyzing alternatives
- Improve retpoline detection and handling
- Improve assembly code coverage on x86
- Provide support for inlined stack switching
* tag 'objtool-core-2021-02-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
objtool: Support stack-swizzle
objtool,x86: Additionally decode: mov %rsp, (%reg)
x86/unwind/orc: Change REG_SP_INDIRECT
x86/power: Support objtool validation in hibernate_asm_64.S
x86/power: Move restore_registers() to top of the file
x86/power: Annotate indirect branches as safe
x86/acpi: Support objtool validation in wakeup_64.S
x86/acpi: Annotate indirect branch as safe
x86/ftrace: Support objtool vmlinux.o validation in ftrace_64.S
x86/xen/pvh: Annotate indirect branch as safe
x86/xen: Support objtool vmlinux.o validation in xen-head.S
x86/xen: Support objtool validation in xen-asm.S
objtool: Add xen_start_kernel() to noreturn list
objtool: Combine UNWIND_HINT_RET_OFFSET and UNWIND_HINT_FUNC
objtool: Add asm version of STACK_FRAME_NON_STANDARD
objtool: Assume only ELF functions do sibling calls
x86/ftrace: Add UNWIND_HINT_FUNC annotation for ftrace_stub
objtool: Support retpoline jump detection for vmlinux.o
objtool: Fix ".cold" section suffix check for newer versions of GCC
objtool: Fix retpoline detection in asm code
...
When objtool encounters the stack-swizzle:
mov %rsp, (%[tos])
mov %[tos], %rsp
...
pop %rsp
Inside a FRAME_POINTER=y build, things go a little screwy because
clearly we're not adjusting the cfa->base. This then results in the
pop %rsp not being detected as a restore of cfa->base so it will turn
into a regular POP and offset the stack, resulting in:
kernel/softirq.o: warning: objtool: do_softirq()+0xdb: return with modified stack frame
Therefore, have "mov %[tos], %rsp" act like a PUSH (it sorta is
anyway) to balance the things out. We're not too concerned with the
actual stack_size for frame-pointer builds, since we don't generate
ORC data for them anyway.
Fixes: aafeb14e9d ("objtool: Support stack-swizzle")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/YC6UC+rc9KKmQrkd@hirez.programming.kicks-ass.net
Sergei Trofimovich