module_alloc() is used everywhere as a mean to allocate memory for code.
Beside being semantically wrong, this unnecessarily ties all subsystems
that need to allocate code, such as ftrace, kprobes and BPF to modules and
puts the burden of code allocation to the modules code.
Several architectures override module_alloc() because of various
constraints where the executable memory can be located and this causes
additional obstacles for improvements of code allocation.
Start splitting code allocation from modules by introducing execmem_alloc()
and execmem_free() APIs.
Initially, execmem_alloc() is a wrapper for module_alloc() and
execmem_free() is a replacement of module_memfree() to allow updating all
call sites to use the new APIs.
Since architectures define different restrictions on placement,
permissions, alignment and other parameters for memory that can be used by
different subsystems that allocate executable memory, execmem_alloc() takes
a type argument, that will be used to identify the calling subsystem and to
allow architectures define parameters for ranges suitable for that
subsystem.
No functional changes.
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Read from an unsafe address with copy_from_kernel_nofault() in
arch_adjust_kprobe_addr() because this function is used before checking
the address is in text or not. Syzcaller bot found a bug and reported
the case if user specifies inaccessible data area,
arch_adjust_kprobe_addr() will cause a kernel panic.
[ mingo: Clarified the comment. ]
Fixes: cc66bb9145 ("x86/ibt,kprobes: Cure sym+0 equals fentry woes")
Reported-by: Qiang Zhang <zzqq0103.hey@gmail.com>
Tested-by: Jinghao Jia <jinghao7@illinois.edu>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/171042945004.154897.2221804961882915806.stgit@devnote2
With the instruction decoder, we are now able to decode and recognize
instructions with opcode extensions. There are more instructions in
these groups that can be boosted:
Group 2: ROL, ROR, RCL, RCR, SHL/SAL, SHR, SAR
Group 3: TEST, NOT, NEG, MUL, IMUL, DIV, IDIV
Group 4: INC, DEC (byte operation)
Group 5: INC, DEC (word/doubleword/quadword operation)
These instructions are not boosted previously because there are reserved
opcodes within the groups, e.g., group 2 with ModR/M.nnn == 110 is
unmapped. As a result, kprobes attached to them requires two int3 traps
as being non-boostable also prevents jump-optimization.
Some simple tests on QEMU show that after boosting and jump-optimization
a single kprobe on these instructions with an empty pre-handler runs 10x
faster (~1000 cycles vs. ~100 cycles).
Since these instructions are mostly ALU operations and do not touch
special registers like RIP, let's boost them so that we get the
performance benefit.
Link: https://lore.kernel.org/all/20240204031300.830475-4-jinghao7@illinois.edu/
Signed-off-by: Jinghao Jia <jinghao7@illinois.edu>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Both INT (INT n, INT1, INT3, INTO) and UD (UD0, UD1, UD2) serve special
purposes in the kernel, e.g., INT3 is used by KGDB and UD2 is involved
in LLVM-KCFI instrumentation. At the same time, attaching kprobes on
these instructions (particularly UD) will pollute the stack trace dumped
in the kernel ring buffer, since the exception is triggered in the copy
buffer rather than the original location.
Check for INT and UD in can_probe and reject any kprobes trying to
attach to these instructions.
Link: https://lore.kernel.org/all/20240204031300.830475-3-jinghao7@illinois.edu/
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinghao Jia <jinghao7@illinois.edu>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Both can_probe and can_boost have int return type but are using int as
boolean in their context.
Refactor both functions to make them actually return boolean.
Link: https://lore.kernel.org/all/20240204031300.830475-2-jinghao7@illinois.edu/
Signed-off-by: Jinghao Jia <jinghao7@illinois.edu>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Prohibit probing on the compiler generated CFI typeid checking code
because it is used for decoding typeid when CFI error happens.
The compiler generates the following instruction sequence for indirect
call checks on x86;
movl -<id>, %r10d ; 6 bytes
addl -4(%reg), %r10d ; 4 bytes
je .Ltmp1 ; 2 bytes
ud2 ; <- regs->ip
And handle_cfi_failure() decodes these instructions (movl and addl)
for the typeid and the target address. Thus if we put a kprobe on
those instructions, the decode will fail and report a wrong typeid
and target address.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/168904025785.116016.12766408611437534723.stgit@devnote2
tall calls properly which can be static calls too
- Add proper struct alt_instr.flags which controls different aspects of
insn patching behavior
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Merge tag 'x86_alternatives_for_v6.3_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm alternatives updates from Borislav Petkov:
- Teach the static_call patching infrastructure to handle conditional
tall calls properly which can be static calls too
- Add proper struct alt_instr.flags which controls different aspects of
insn patching behavior
* tag 'x86_alternatives_for_v6.3_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/static_call: Add support for Jcc tail-calls
x86/alternatives: Teach text_poke_bp() to patch Jcc.d32 instructions
x86/alternatives: Introduce int3_emulate_jcc()
x86/alternatives: Add alt_instr.flags
- Optimize perf_sample_data layout
- Prepare sample data handling for BPF integration
- Update the x86 PMU driver for Intel Meteor Lake
- Restructure the x86 uncore code to fix a SPR (Sapphire Rapids)
discovery breakage
- Fix the x86 Zhaoxin PMU driver
- Cleanups
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf updates from Ingo Molnar:
- Optimize perf_sample_data layout
- Prepare sample data handling for BPF integration
- Update the x86 PMU driver for Intel Meteor Lake
- Restructure the x86 uncore code to fix a SPR (Sapphire Rapids)
discovery breakage
- Fix the x86 Zhaoxin PMU driver
- Cleanups
* tag 'perf-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
perf/x86/intel/uncore: Add Meteor Lake support
x86/perf/zhaoxin: Add stepping check for ZXC
perf/x86/intel/ds: Fix the conversion from TSC to perf time
perf/x86/uncore: Don't WARN_ON_ONCE() for a broken discovery table
perf/x86/uncore: Add a quirk for UPI on SPR
perf/x86/uncore: Ignore broken units in discovery table
perf/x86/uncore: Fix potential NULL pointer in uncore_get_alias_name
perf/x86/uncore: Factor out uncore_device_to_die()
perf/core: Call perf_prepare_sample() before running BPF
perf/core: Introduce perf_prepare_header()
perf/core: Do not pass header for sample ID init
perf/core: Set data->sample_flags in perf_prepare_sample()
perf/core: Add perf_sample_save_brstack() helper
perf/core: Add perf_sample_save_raw_data() helper
perf/core: Add perf_sample_save_callchain() helper
perf/core: Save the dynamic parts of sample data size
x86/kprobes: Use switch-case for 0xFF opcodes in prepare_emulation
perf/core: Change the layout of perf_sample_data
perf/x86/msr: Add Meteor Lake support
perf/x86/cstate: Add Meteor Lake support
...
Commit 3bc753c06d ("kbuild: treat char as always unsigned") broke
kprobes. Setting a probe-point on 1 byte conditional jump can cause the
kernel to crash when the (signed) relative jump offset gets treated as
unsigned.
Fix by replacing the unsigned 'immediate.bytes' (plus a cast) with the
signed 'immediate.value' when assigning to the relative jump offset.
[ dhansen: clarified changelog ]
Fixes: 3bc753c06d ("kbuild: treat char as always unsigned")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230208071708.4048-1-namit%40vmware.com
Move the kprobe Jcc emulation into int3_emulate_jcc() so it can be
used by more code -- specifically static_call() will need this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20230123210607.057678245@infradead.org
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Merge tag 'v6.2-rc4' into perf/core, to pick up fixes
Move from the -rc1 base to the fresher -rc4 kernel that
has various fixes included, before applying a larger
patchset.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
For the `FF /digit` opcodes in prepare_emulation, use switch-case
instead of hand-written code to make the logic easier to understand.
Signed-off-by: Chuang Wang <nashuiliang@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20221129084022.718355-1-nashuiliang@gmail.com
Drop removed INT3 handling code from kprobe_int3_handler() because this
case (get_kprobe() doesn't return corresponding kprobe AND the INT3 is
removed) must not happen with the kprobe managed INT3, but can happen
with the non-kprobe INT3, which should be handled by other callbacks.
For the kprobe managed INT3, it is already safe. The commit 5c02ece818
("x86/kprobes: Fix ordering while text-patching") introduced
text_poke_sync() to the arch_disarm_kprobe() right after removing INT3.
Since this text_poke_sync() uses IPI to call sync_core() on all online
cpus, that ensures that all running INT3 exception handlers have done.
And, the unregister_kprobe() will remove the kprobe from the hash table
after arch_disarm_kprobe().
Thus, when the kprobe managed INT3 hits, kprobe_int3_handler() should
be able to find corresponding kprobe always by get_kprobe(). If it can
not find any kprobe, this means that is NOT a kprobe managed INT3.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/166981518895.1131462.4693062055762912734.stgit@devnote3
Since the CONFIG_RETHUNK and CONFIG_SLS will use INT3 for stopping
speculative execution after RET instruction, kprobes always failes to
check the probed instruction boundary by decoding the function body if
the probed address is after such sequence. (Note that some conditional
code blocks will be placed after function return, if compiler decides
it is not on the hot path.)
This is because kprobes expects kgdb puts the INT3 as a software
breakpoint and it will replace the original instruction.
But these INT3 are not such purpose, it doesn't need to recover the
original instruction.
To avoid this issue, kprobes checks whether the INT3 is owned by
kgdb or not, and if so, stop decoding and make it fail. The other
INT3 will come from CONFIG_RETHUNK/CONFIG_SLS and those can be
treated as a one-byte instruction.
Fixes: e463a09af2 ("x86: Add straight-line-speculation mitigation")
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/167146051026.1374301.392728975473572291.stgit@devnote3
* Randomize the per-cpu entry areas
Cleanups:
* Have CR3_ADDR_MASK use PHYSICAL_PAGE_MASK instead of open
coding it
* Move to "native" set_memory_rox() helper
* Clean up pmd_get_atomic() and i386-PAE
* Remove some unused page table size macros
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Merge tag 'x86_mm_for_6.2_v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mm updates from Dave Hansen:
"New Feature:
- Randomize the per-cpu entry areas
Cleanups:
- Have CR3_ADDR_MASK use PHYSICAL_PAGE_MASK instead of open coding it
- Move to "native" set_memory_rox() helper
- Clean up pmd_get_atomic() and i386-PAE
- Remove some unused page table size macros"
* tag 'x86_mm_for_6.2_v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (35 commits)
x86/mm: Ensure forced page table splitting
x86/kasan: Populate shadow for shared chunk of the CPU entry area
x86/kasan: Add helpers to align shadow addresses up and down
x86/kasan: Rename local CPU_ENTRY_AREA variables to shorten names
x86/mm: Populate KASAN shadow for entire per-CPU range of CPU entry area
x86/mm: Recompute physical address for every page of per-CPU CEA mapping
x86/mm: Rename __change_page_attr_set_clr(.checkalias)
x86/mm: Inhibit _PAGE_NX changes from cpa_process_alias()
x86/mm: Untangle __change_page_attr_set_clr(.checkalias)
x86/mm: Add a few comments
x86/mm: Fix CR3_ADDR_MASK
x86/mm: Remove P*D_PAGE_MASK and P*D_PAGE_SIZE macros
mm: Convert __HAVE_ARCH_P..P_GET to the new style
mm: Remove pointless barrier() after pmdp_get_lockless()
x86/mm/pae: Get rid of set_64bit()
x86_64: Remove pointless set_64bit() usage
x86/mm/pae: Be consistent with pXXp_get_and_clear()
x86/mm/pae: Use WRITE_ONCE()
x86/mm/pae: Don't (ab)use atomic64
mm/gup: Fix the lockless PMD access
...
Instead of resetting permissions all over the place when freeing module
memory tell the vmalloc code to do so. Avoids the exercise for the next
upcoming user.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111143.406703869@infradead.org
An unused macro reported by [-Wunused-macros].
This macro is used to access the sp in pt_regs because at that time
x86_32 can only get sp by kernel_stack_pointer(regs).
'3c88c692c287 ("x86/stackframe/32: Provide consistent pt_regs")'
This commit have unified the pt_regs and from them we can get sp from
pt_regs with regs->sp easily. Nowhere is using this macro anymore.
Refrencing pt_regs directly is more clear. Remove this macro for
code cleaning.
Link: https://lkml.kernel.org/r/20220924072629.104759-1-chenzhongjin@huawei.com
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
When kprobes emulates JNG/JNLE instructions on x86 it uses the wrong
condition. For JNG (opcode: 0F 8E), according to Intel SDM, the jump is
performed if (ZF == 1 or SF != OF). However the kernel emulation
currently uses 'and' instead of 'or'.
As a result, setting a kprobe on JNG/JNLE might cause the kernel to
behave incorrectly whenever the kprobe is hit.
Fix by changing the 'and' to 'or'.
Fixes: 6256e668b7 ("x86/kprobes: Use int3 instead of debug trap for single-step")
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220813225943.143767-1-namit@vmware.com
Replaces the kretprobe code with rethook on x86. With this patch,
kretprobe on x86 uses the rethook instead of kretprobe specific
trampoline code.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/164826163692.2455864.13745421016848209527.stgit@devnote2
Annotate away some of the generic code references. This is things
where we take the address of a symbol for exception handling or return
addresses (eg. context switch).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.877758523@infradead.org
In order to allow kprobes to skip the ENDBR instructions at sym+0 for
X86_KERNEL_IBT builds, change _kprobe_addr() to take an architecture
callback to inspect the function at hand and modify the offset if
needed.
This streamlines the existing interface to cover more cases and
require less hooks. Once PowerPC gets fully converted there will only
be the one arch hook.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.405947704@infradead.org
Currently a lot of ftrace code assumes __fentry__ is at sym+0. However
with Intel IBT enabled the first instruction of a function will most
likely be ENDBR.
Change ftrace_location() to not only return the __fentry__ location
when called for the __fentry__ location, but also when called for the
sym+0 location.
Then audit/update all callsites of this function to consistently use
these new semantics.
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.227581603@infradead.org
Replace all ret/retq instructions with ASM_RET in preparation of
making it more than a single instruction.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211204134907.964635458@infradead.org
In x86, the fake return address on the stack saved by
__kretprobe_trampoline() will be replaced with the real return
address after returning from trampoline_handler(). Before fixing
the return address, the real return address can be found in the
'current->kretprobe_instances'.
However, since there is a window between updating the
'current->kretprobe_instances' and fixing the address on the stack,
if an interrupt happens at that timing and the interrupt handler
does stacktrace, it may fail to unwind because it can not get
the correct return address from 'current->kretprobe_instances'.
This will eliminate that window by fixing the return address
right before updating 'current->kretprobe_instances'.
Link: https://lkml.kernel.org/r/163163057094.489837.9044470370440745866.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Change __kretprobe_trampoline() to push the address of the
__kretprobe_trampoline() as a fake return address at the bottom
of the stack frame. This fake return address will be replaced
with the correct return address in the trampoline_handler().
With this change, the ORC unwinder can check whether the return
address is modified by kretprobes or not.
Link: https://lkml.kernel.org/r/163163054185.489837.14338744048957727386.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Add UNWIND_HINT_FUNC on __kretprobe_trampoline() code so that ORC
information is generated on the __kretprobe_trampoline() correctly.
Also, this uses STACK_FRAME_NON_STANDARD_FP(), CONFIG_FRAME_POINTER-
-specific version of STACK_FRAME_NON_STANDARD().
Link: https://lkml.kernel.org/r/163163049242.489837.11970969750993364293.stgit@devnote2
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Since now there is kretprobe_trampoline_addr() for referring the
address of kretprobe trampoline code, we don't need to access
kretprobe_trampoline directly.
Make it harder to refer by renaming it to __kretprobe_trampoline().
Link: https://lkml.kernel.org/r/163163045446.489837.14510577516938803097.stgit@devnote2
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The __kretprobe_trampoline_handler() callback, called from low level
arch kprobes methods, has the 'trampoline_address' parameter, which is
entirely superfluous as it basically just replicates:
dereference_kernel_function_descriptor(kretprobe_trampoline)
In fact we had bugs in arch code where it wasn't replicated correctly.
So remove this superfluous parameter and use kretprobe_trampoline_addr()
instead.
Link: https://lkml.kernel.org/r/163163044546.489837.13505751885476015002.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Merge more updates from Andrew Morton:
"190 patches.
Subsystems affected by this patch series: mm (hugetlb, userfaultfd,
vmscan, kconfig, proc, z3fold, zbud, ras, mempolicy, memblock,
migration, thp, nommu, kconfig, madvise, memory-hotplug, zswap,
zsmalloc, zram, cleanups, kfence, and hmm), procfs, sysctl, misc,
core-kernel, lib, lz4, checkpatch, init, kprobes, nilfs2, hfs,
signals, exec, kcov, selftests, compress/decompress, and ipc"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (190 commits)
ipc/util.c: use binary search for max_idx
ipc/sem.c: use READ_ONCE()/WRITE_ONCE() for use_global_lock
ipc: use kmalloc for msg_queue and shmid_kernel
ipc sem: use kvmalloc for sem_undo allocation
lib/decompressors: remove set but not used variabled 'level'
selftests/vm/pkeys: exercise x86 XSAVE init state
selftests/vm/pkeys: refill shadow register after implicit kernel write
selftests/vm/pkeys: handle negative sys_pkey_alloc() return code
selftests/vm/pkeys: fix alloc_random_pkey() to make it really, really random
kcov: add __no_sanitize_coverage to fix noinstr for all architectures
exec: remove checks in __register_bimfmt()
x86: signal: don't do sas_ss_reset() until we are certain that sigframe won't be abandoned
hfsplus: report create_date to kstat.btime
hfsplus: remove unnecessary oom message
nilfs2: remove redundant continue statement in a while-loop
kprobes: remove duplicated strong free_insn_page in x86 and s390
init: print out unknown kernel parameters
checkpatch: do not complain about positive return values starting with EPOLL
checkpatch: improve the indented label test
checkpatch: scripts/spdxcheck.py now requires python3
...
free_insn_page() in x86 and s390 is same with the common weak function in
kernel/kprobes.c. Plus, the comment "Recover page to RW mode before
releasing it" in x86 seems insensible to be there since resetting mapping
is done by common code in vfree() of module_memfree(). So drop these two
duplicated strong functions and related comment, then mark the common one
in kernel/kprobes.c strong.
Link: https://lkml.kernel.org/r/20210608065736.32656-1-song.bao.hua@hisilicon.com
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Qi Liu <liuqi115@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Kprobes has a counter 'nmissed', that is used to count the number of
times a probe handler was not called. This generally happens when we hit
a kprobe while handling another kprobe.
However, if one of the probe handlers causes a fault, we are currently
incrementing 'nmissed'. The comment in fault handler indicates that this
can be used to account faults taken by the probe handlers. But, this has
never been the intention as is evident from the comment above 'nmissed'
in 'struct kprobe':
/*count the number of times this probe was temporarily disarmed */
unsigned long nmissed;
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lkml.kernel.org/r/20210601120150.672652-1-naveen.n.rao@linux.vnet.ibm.com
The reason for kprobe::fault_handler(), as given by their comment:
* We come here because instructions in the pre/post
* handler caused the page_fault, this could happen
* if handler tries to access user space by
* copy_from_user(), get_user() etc. Let the
* user-specified handler try to fix it first.
Is just plain bad. Those other handlers are ran from non-preemptible
context and had better use _nofault() functions. Also, there is no
upstream usage of this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20210525073213.561116662@infradead.org
Add a helper to decode kernel instructions; there's no point in
endlessly repeating those last two arguments.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210326151259.379242587@infradead.org
Address this GCC warning:
arch/x86/kernel/kprobes/core.c:940:1:
warning: 'inline' is not at beginning of declaration [-Wold-style-declaration]
940 | static int nokprobe_inline kprobe_is_ss(struct kprobe_ctlblk *kcb)
| ^~~~~~
[ mingo: Tidied up the changelog. ]
Fixes: 6256e668b7: ("x86/kprobes: Use int3 instead of debug trap for single-step")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20210324144502.1154883-1-weiyongjun1@huawei.com
Fix can_boost() to identify indirect jmp and others using range case
correctly.
Since the condition in switch statement is opcode & 0xf0, it can not
evaluate to 0xff case. This should be under the 0xf0 case. However,
there is no reason to use the conbinations of the bit-masked condition
and lower bit checking.
Use range case to clean up the switch statement too.
Fixes: 6256e668b7 ("x86/kprobes: Use int3 instead of debug trap for single-step")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/161666692308.1120877.4675552834049546493.stgit@devnote2
There are 2 bugs in the can_boost() function because of using
x86 insn decoder. Since the insn->opcode never has a prefix byte,
it can not find CS override prefix in it. And the insn->attr is
the attribute of the opcode, thus inat_is_address_size_prefix(
insn->attr) always returns false.
Fix those by checking each prefix bytes with for_each_insn_prefix
loop and getting the correct attribute for each prefix byte.
Also, this removes unlikely, because this is a slow path.
Fixes: a8d11cd071 ("kprobes/x86: Consolidate insn decoder users for copying code")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/161666691162.1120877.2808435205294352583.stgit@devnote2
Use int3 instead of debug trap exception for single-stepping the
probed instructions. Some instructions which change the ip
registers or modify IF flags are emulated because those are not
able to be single-stepped by int3 or may allow the interrupt
while single-stepping.
This actually changes the kprobes behavior.
- kprobes can not probe following instructions; int3, iret,
far jmp/call which get absolute address as immediate,
indirect far jmp/call, indirect near jmp/call with addressing
by memory (register-based indirect jmp/call are OK), and
vmcall/vmlaunch/vmresume/vmxoff.
- If the kprobe post_handler doesn't set before registering,
it may not be called in some case even if you set it afterwards.
(IOW, kprobe booster is enabled at registration, user can not
change it)
But both are rare issue, unsupported instructions will not be
used in the kernel (or rarely used), and post_handlers are
rarely used (I don't see it except for the test code).
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/161469874601.49483.11985325887166921076.stgit@devnote2
Since Grp5 far indirect JMP is FF "mod 101 r/m", it should be
(modrm & 0x38) == 0x28, and near indirect JMP is also 0x38 == 0x20.
So we can mask modrm with 0x30 and check 0x20.
This is actually what the original code does, it also doesn't care
the last bit. So the result code is same.
Thus, I think this is just a cosmetic cleanup.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/161469873475.49483.13257083019966335137.stgit@devnote2
Since the opcodes start from 0xff are group5 instruction group which is
not 2 bytes opcode but the extended opcode determined by the MOD/RM byte.
The commit abd82e533d ("x86/kprobes: Do not decode opcode in resume_execution()")
used insn->opcode.bytes[1], but that is not correct. We have to refer
the insn->modrm.bytes[1] instead.
Fixes: abd82e533d ("x86/kprobes: Do not decode opcode in resume_execution()")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/161469872400.49483.18214724458034233166.stgit@devnote2
This ensures that a NOP is a NOP and not a random other instruction that
is also a NOP. It allows simplification of dynamic code patching that
wants to verify existing code before writing new instructions (ftrace,
jump_label, static_call, etc..).
Differentiating on NOPs is not a feature.
This pessimises 32bit (DONTCARE) and 32bit on 64bit CPUs (CARELESS).
32bit is not a performance target.
Everything x86_64 since AMD K10 (2007) and Intel IvyBridge (2012) is
fine with using NOPL (as opposed to prefix NOP). And per FEATURE_NOPL
being required for x86_64, all x86_64 CPUs can use NOPL. So stop
caring about NOPs, simplify things and get on with life.
[ The problem seems to be that some uarchs can only decode NOPL on a
single front-end port while others have severe decode penalties for
excessive prefixes. All modern uarchs can handle both, except Atom,
which has prefix penalties. ]
[ Also, much doubt you can actually measure any of this on normal
workloads. ]
After this, FEATURE_NOPL is unused except for required-features for
x86_64. FEATURE_K8 is only used for PTI.
[ bp: Kernel build measurements showed ~0.3s slowdown on Sandybridge
which is hardly a slowdown. Get rid of X86_FEATURE_K7, while at it. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> # bpf
Acked-by: Linus Torvalds <torvalds@linuxfoundation.org>
Link: https://lkml.kernel.org/r/20210312115749.065275711@infradead.org
Currently, kprobes decodes the opcode right after single-stepping in
resume_execution(). But the opcode was already decoded while preparing
arch_specific_insn in arch_copy_kprobe().
Decode the opcode in arch_copy_kprobe() instead of in resume_execution()
and set some flags which classify the opcode for the resuming process.
[ bp: Massage commit message. ]
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lkml.kernel.org/r/160830072561.349576.3014979564448023213.stgit@devnote2
In preparation to enable -Wimplicit-fallthrough for Clang, fix a warning
by explicitly adding a break statement instead of just letting the code
fall through to the next case.
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://github.com/KSPP/linux/issues/115
Fix to restore BTF if single-stepping causes a page fault and
it is cancelled.
Usually the BTF flag was restored when the single stepping is done
(in resume_execution()). However, if a page fault happens on the
single stepping instruction, the fault handler is invoked and
the single stepping is cancelled. Thus, the BTF flag is not
restored.
Fixes: 1ecc798c67 ("x86: debugctlmsr kprobes")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/160389546985.106936.12727996109376240993.stgit@devnote2
