I found a null pointer reference in arch_prepare_kprobe():
# echo 'p cmdline_proc_show' > kprobe_events
# echo 'p cmdline_proc_show+16' >> kprobe_events
Kernel attempted to read user page (0) - exploit attempt? (uid: 0)
BUG: Kernel NULL pointer dereference on read at 0x00000000
Faulting instruction address: 0xc000000000050bfc
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV
Modules linked in:
CPU: 0 PID: 122 Comm: sh Not tainted 6.0.0-rc3-00007-gdcf8e5633e2e #10
NIP: c000000000050bfc LR: c000000000050bec CTR: 0000000000005bdc
REGS: c0000000348475b0 TRAP: 0300 Not tainted (6.0.0-rc3-00007-gdcf8e5633e2e)
MSR: 9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 88002444 XER: 20040006
CFAR: c00000000022d100 DAR: 0000000000000000 DSISR: 40000000 IRQMASK: 0
...
NIP arch_prepare_kprobe+0x10c/0x2d0
LR arch_prepare_kprobe+0xfc/0x2d0
Call Trace:
0xc0000000012f77a0 (unreliable)
register_kprobe+0x3c0/0x7a0
__register_trace_kprobe+0x140/0x1a0
__trace_kprobe_create+0x794/0x1040
trace_probe_create+0xc4/0xe0
create_or_delete_trace_kprobe+0x2c/0x80
trace_parse_run_command+0xf0/0x210
probes_write+0x20/0x40
vfs_write+0xfc/0x450
ksys_write+0x84/0x140
system_call_exception+0x17c/0x3a0
system_call_vectored_common+0xe8/0x278
--- interrupt: 3000 at 0x7fffa5682de0
NIP: 00007fffa5682de0 LR: 0000000000000000 CTR: 0000000000000000
REGS: c000000034847e80 TRAP: 3000 Not tainted (6.0.0-rc3-00007-gdcf8e5633e2e)
MSR: 900000000280f033 <SF,HV,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 44002408 XER: 00000000
The address being probed has some special:
cmdline_proc_show: Probe based on ftrace
cmdline_proc_show+16: Probe for the next instruction at the ftrace location
The ftrace-based kprobe does not generate kprobe::ainsn::insn, it gets
set to NULL. In arch_prepare_kprobe() it will check for:
...
prev = get_kprobe(p->addr - 1);
preempt_enable_no_resched();
if (prev && ppc_inst_prefixed(ppc_inst_read(prev->ainsn.insn))) {
...
If prev is based on ftrace, 'ppc_inst_read(prev->ainsn.insn)' will occur
with a null pointer reference. At this point prev->addr will not be a
prefixed instruction, so the check can be skipped.
Check if prev is ftrace-based kprobe before reading 'prev->ainsn.insn'
to fix this problem.
Fixes: b4657f7650 ("powerpc/kprobes: Don't allow breakpoints on suffixes")
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
[mpe: Trim oops]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220923093253.177298-1-lihuafei1@huawei.com
The ppc_inst_as_str() macro tries to make printing variable length,
aka "prefixed", instructions convenient. It mostly succeeds, but it does
hide an on-stack buffer, which triggers stack protector.
More problematically it doesn't compile at all with GCC 12,
with -Wdangling-pointer, due to the fact that it returns the char buffer
declared inside the macro:
arch/powerpc/kernel/trace/ftrace.c: In function '__ftrace_modify_call':
./include/linux/printk.h:475:44: error: using a dangling pointer to '__str' [-Werror=dangling-pointer=]
475 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
...
arch/powerpc/kernel/trace/ftrace.c:567:17: note: in expansion of macro 'pr_err'
567 | pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
| ^~~~~~
./arch/powerpc/include/asm/inst.h:156:14: note: '__str' declared here
156 | char __str[PPC_INST_STR_LEN]; \
| ^~~~~
This could be fixed by having the caller declare the buffer, but in some
places there'd need to be two buffers. In all cases where
ppc_inst_as_str() is used the output is not really meant for user
consumption, it's almost always indicative of a kernel bug.
A simpler solution is to just print the value as an unsigned long. For
normal instructions the output is identical. For prefixed instructions
the value is printed as a single 64-bit quantity, whereas previously the
low half was printed first. But that is good enough for debug output,
especially as prefixed instructions will be rare in kernel code in
practice.
Old:
c000000000111170 60420000 ori r2,r2,0
c000000000111174 04100001 e580fb00 .long 0xe580fb0004100001
New:
c00000000010f90c 60420000 ori r2,r2,0
c00000000010f910 e580fb0004100001 .long 0xe580fb0004100001
Reported-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reported-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/20220531065936.3674348-1-mpe@ellerman.id.au
Per the ISA, a Trace interrupt is not generated for:
- [h|u]rfi[d]
- rfscv
- sc, scv, and Trap instructions that trap
- Power-Saving Mode instructions
- other instructions that cause interrupts (other than Trace interrupts)
- the first instructions of any interrupt handler (applies to Branch and Single Step tracing;
CIABR matches may still occur)
- instructions that are emulated by software
Add a helper to check for instructions belonging to the first four
categories above and to reject kprobes, uprobes and xmon breakpoints on
such instructions. We reject probing on instructions belonging to these
categories across all ISA versions and across both BookS and BookE.
For trap instructions, we can't know in advance if they can cause a
trap, and there is no good reason to allow probing on those. Also,
uprobes already refuses to probe trap instructions and kprobes does not
allow probes on trap instructions used for kernel warnings and bugs. As
such, stop allowing any type of probes/breakpoints on trap instruction
across uprobes, kprobes and xmon.
For some of the fp/altivec instructions that can generate an interrupt
and which we emulate in the kernel (altivec assist, for example), we
check and turn off single stepping in emulate_single_step().
Instructions generating a DSI are restarted and single stepping normally
completes once the instruction is completed.
In uprobes, if a single stepped instruction results in a non-fatal
signal to be delivered to the task, such signals are "delayed" until
after the instruction completes. For fatal signals, single stepping is
cancelled and the instruction restarted in-place so that core dump
captures proper addresses.
In kprobes, we do not allow probes on instructions having an extable
entry and we also do not allow probing interrupt vectors.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f56ee979d50b8711fae350fc97870f3ca34acd75.1648648712.git.naveen.n.rao@linux.vnet.ibm.com
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
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>
~15 years ago kprobes grew the 'arch_deref_entry_point()' __weak function:
3d7e33825d: ("jprobes: make jprobes a little safer for users")
But this is just open-coded dereference_symbol_descriptor() in essence, and
its obscure nature was causing bugs.
Just use the real thing and remove arch_deref_entry_point().
Link: https://lkml.kernel.org/r/163163043630.489837.7924988885652708696.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>
- A big series refactoring parts of our KVM code, and converting some to C.
- Support for ARCH_HAS_SET_MEMORY, and ARCH_HAS_STRICT_MODULE_RWX on some CPUs.
- Support for the Microwatt soft-core.
- Optimisations to our interrupt return path on 64-bit.
- Support for userspace access to the NX GZIP accelerator on PowerVM on Power10.
- Enable KUAP and KUEP by default on 32-bit Book3S CPUs.
- Other smaller features, fixes & cleanups.
Thanks to: Andy Shevchenko, Aneesh Kumar K.V, Arnd Bergmann, Athira Rajeev, Baokun Li,
Benjamin Herrenschmidt, Bharata B Rao, Christophe Leroy, Daniel Axtens, Daniel Henrique
Barboza, Finn Thain, Geoff Levand, Haren Myneni, Jason Wang, Jiapeng Chong, Joel Stanley,
Jordan Niethe, Kajol Jain, Nathan Chancellor, Nathan Lynch, Naveen N. Rao, Nicholas
Piggin, Nick Desaulniers, Paul Mackerras, Russell Currey, Sathvika Vasireddy, Shaokun
Zhang, Stephen Rothwell, Sudeep Holla, Suraj Jitindar Singh, Tom Rix, Vaibhav Jain,
YueHaibing, Zhang Jianhua, Zhen Lei.
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Merge tag 'powerpc-5.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
- A big series refactoring parts of our KVM code, and converting some
to C.
- Support for ARCH_HAS_SET_MEMORY, and ARCH_HAS_STRICT_MODULE_RWX on
some CPUs.
- Support for the Microwatt soft-core.
- Optimisations to our interrupt return path on 64-bit.
- Support for userspace access to the NX GZIP accelerator on PowerVM on
Power10.
- Enable KUAP and KUEP by default on 32-bit Book3S CPUs.
- Other smaller features, fixes & cleanups.
Thanks to: Andy Shevchenko, Aneesh Kumar K.V, Arnd Bergmann, Athira
Rajeev, Baokun Li, Benjamin Herrenschmidt, Bharata B Rao, Christophe
Leroy, Daniel Axtens, Daniel Henrique Barboza, Finn Thain, Geoff Levand,
Haren Myneni, Jason Wang, Jiapeng Chong, Joel Stanley, Jordan Niethe,
Kajol Jain, Nathan Chancellor, Nathan Lynch, Naveen N. Rao, Nicholas
Piggin, Nick Desaulniers, Paul Mackerras, Russell Currey, Sathvika
Vasireddy, Shaokun Zhang, Stephen Rothwell, Sudeep Holla, Suraj Jitindar
Singh, Tom Rix, Vaibhav Jain, YueHaibing, Zhang Jianhua, and Zhen Lei.
* tag 'powerpc-5.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (218 commits)
powerpc: Only build restart_table.c for 64s
powerpc/64s: move ret_from_fork etc above __end_soft_masked
powerpc/64s/interrupt: clean up interrupt return labels
powerpc/64/interrupt: add missing kprobe annotations on interrupt exit symbols
powerpc/64: enable MSR[EE] in irq replay pt_regs
powerpc/64s/interrupt: preserve regs->softe for NMI interrupts
powerpc/64s: add a table of implicit soft-masked addresses
powerpc/64e: remove implicit soft-masking and interrupt exit restart logic
powerpc/64e: fix CONFIG_RELOCATABLE build warnings
powerpc/64s: fix hash page fault interrupt handler
powerpc/4xx: Fix setup_kuep() on SMP
powerpc/32s: Fix setup_{kuap/kuep}() on SMP
powerpc/interrupt: Use names in check_return_regs_valid()
powerpc/interrupt: Also use exit_must_hard_disable() on PPC32
powerpc/sysfs: Replace sizeof(arr)/sizeof(arr[0]) with ARRAY_SIZE
powerpc/ptrace: Refactor regs_set_return_{msr/ip}
powerpc/ptrace: Move set_return_regs_changed() before regs_set_return_{msr/ip}
powerpc/stacktrace: Fix spurious "stale" traces in raise_backtrace_ipi()
powerpc/pseries/vas: Include irqdomain.h
powerpc: mark local variables around longjmp as volatile
...
- Platform PMU driver updates:
- x86 Intel uncore driver updates for Skylake (SNR) and Icelake (ICX) servers
- Fix RDPMC support
- Fix [extended-]PEBS-via-PT support
- Fix Sapphire Rapids event constraints
- Fix :ppp support on Sapphire Rapids
- Fix fixed counter sanity check on Alder Lake & X86_FEATURE_HYBRID_CPU
- Other heterogenous-PMU fixes
- Kprobes:
- Remove the unused and misguided kprobe::fault_handler callbacks.
- Warn about kprobes taking a page fault.
- Fix the 'nmissed' stat counter.
- Misc cleanups and fixes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf events updates from Ingo Molnar:
- Platform PMU driver updates:
- x86 Intel uncore driver updates for Skylake (SNR) and Icelake (ICX) servers
- Fix RDPMC support
- Fix [extended-]PEBS-via-PT support
- Fix Sapphire Rapids event constraints
- Fix :ppp support on Sapphire Rapids
- Fix fixed counter sanity check on Alder Lake & X86_FEATURE_HYBRID_CPU
- Other heterogenous-PMU fixes
- Kprobes:
- Remove the unused and misguided kprobe::fault_handler callbacks.
- Warn about kprobes taking a page fault.
- Fix the 'nmissed' stat counter.
- Misc cleanups and fixes.
* tag 'perf-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: Fix task context PMU for Hetero
perf/x86/intel: Fix instructions:ppp support in Sapphire Rapids
perf/x86/intel: Add more events requires FRONTEND MSR on Sapphire Rapids
perf/x86/intel: Fix fixed counter check warning for some Alder Lake
perf/x86/intel: Fix PEBS-via-PT reload base value for Extended PEBS
perf/x86: Reset the dirty counter to prevent the leak for an RDPMC task
kprobes: Do not increment probe miss count in the fault handler
x86,kprobes: WARN if kprobes tries to handle a fault
kprobes: Remove kprobe::fault_handler
uprobes: Update uprobe_write_opcode() kernel-doc comment
perf/hw_breakpoint: Fix DocBook warnings in perf hw_breakpoint
perf/core: Fix DocBook warnings
perf/core: Make local function perf_pmu_snapshot_aux() static
perf/x86/intel/uncore: Enable I/O stacks to IIO PMON mapping on ICX
perf/x86/intel/uncore: Enable I/O stacks to IIO PMON mapping on SNR
perf/x86/intel/uncore: Generalize I/O stacks to PMON mapping procedure
perf/x86/intel/uncore: Drop unnecessary NULL checks after container_of()
When an interrupt is taken, the SRR registers are set to return to where
it left off. Unless they are modified in the meantime, or the return
address or MSR are modified, there is no need to reload these registers
when returning from interrupt.
Introduce per-CPU flags that track the validity of SRR and HSRR
registers. These are cleared when returning from interrupt, when
using the registers for something else (e.g., OPAL calls), when
adjusting the return address or MSR of a context, and when context
switching (which changes the return address and MSR).
This improves the performance of interrupt returns.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fold in fixup patch from Nick]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210617155116.2167984-5-npiggin@gmail.com
Add the arch specific insn page allocator for powerpc. This allocates
ROX pages if STRICT_KERNEL_RWX is enabled. These pages are only written
to with patch_instruction() which is able to write RO pages.
Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[jpn: Reword commit message, switch to __vmalloc_node_range()]
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210609013431.9805-5-jniethe5@gmail.com
'struct ppc_inst' is an internal representation of an instruction, but
in-memory instructions are and will remain a table of 'u32' forever.
Replace all 'struct ppc_inst *' used for locating an instruction in
memory by 'u32 *'. This removes a lot of undue casts to 'struct
ppc_inst *'.
It also helps locating ab-use of 'struct ppc_inst' dereference.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Fix ppc_inst_next(), use u32 instead of unsigned int]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7062722b087228e42cbd896e39bfdf526d6a340a.1621516826.git.christophe.leroy@csgroup.eu
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
When checking if the probed instruction is the suffix of a prefixed
instruction, we access the instruction at the previous word. If the
probed instruction is the very first word of a module, we can end up
trying to access an invalid page.
Fix this by skipping the check for all instructions at the beginning of
a page. Prefixed instructions cannot cross a 64-byte boundary and as
such, we don't expect to encounter a suffix as the very first word in a
page for kernel text. Even if there are prefixed instructions crossing
a page boundary (from a module, for instance), the instruction will be
illegal, so preventing probing on the suffix of such prefix instructions
isn't worthwhile.
Fixes: b4657f7650 ("powerpc/kprobes: Don't allow breakpoints on suffixes")
Cc: stable@vger.kernel.org # v5.8+
Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/0df9a032a05576a2fa8e97d1b769af2ff0eafbd6.1621416666.git.naveen.n.rao@linux.vnet.ibm.com
There are quite a few places where instructions are printed, this is
done using a '%x' format specifier. With the introduction of prefixed
instructions, this does not work well. Currently in these places,
ppc_inst_val() is used for the value for %x so only the first word of
prefixed instructions are printed.
When the instructions are word instructions, only a single word should
be printed. For prefixed instructions both the prefix and suffix should
be printed. To accommodate both of these situations, instead of a '%x'
specifier use '%s' and introduce a helper, __ppc_inst_as_str() which
returns a char *. The char * __ppc_inst_as_str() returns is buffer that
is passed to it by the caller.
It is cumbersome to require every caller of __ppc_inst_as_str() to now
declare a buffer. To make it more convenient to use __ppc_inst_as_str(),
wrap it in a macro that uses a compound statement to allocate a buffer
on the caller's stack before calling it.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Acked-by: Segher Boessenkool <segher@kernel.crashing.org>
[mpe: Drop 0x prefix to match most existings uses, especially xmon]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200602052728.18227-1-jniethe5@gmail.com
Better describe what this helper does, and match the naming of
copy_from_kernel_nofault.
Also switch the argument order around, so that it acts and looks
like get_user().
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently all instructions have the same length, but in preparation for
prefixed instructions introduce a function for returning instruction
length.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-18-jniethe5@gmail.com
Instead of using memcpy() and flush_icache_range() use
patch_instruction() which not only accomplishes both of these steps but
will also make it easier to add support for prefixed instructions.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-16-jniethe5@gmail.com
Prefixed instructions will mean there are instructions of different
length. As a result dereferencing a pointer to an instruction will not
necessarily give the desired result. Introduce a function for reading
instructions from memory into the instruction data type.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-13-jniethe5@gmail.com
Currently unsigned ints are used to represent instructions on powerpc.
This has worked well as instructions have always been 4 byte words.
However, ISA v3.1 introduces some changes to instructions that mean
this scheme will no longer work as well. This change is Prefixed
Instructions. A prefixed instruction is made up of a word prefix
followed by a word suffix to make an 8 byte double word instruction.
No matter the endianness of the system the prefix always comes first.
Prefixed instructions are only planned for powerpc64.
Introduce a ppc_inst type to represent both prefixed and word
instructions on powerpc64 while keeping it possible to exclusively
have word instructions on powerpc32.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
[mpe: Fix compile error in emulate_spe()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-12-jniethe5@gmail.com
In preparation for introducing a more complicated instruction type to
accommodate prefixed instructions use an accessor for getting an
instruction as a u32.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-8-jniethe5@gmail.com
In preparation for instructions having a more complex data type start
using a macro, ppc_inst(), for making an instruction out of a u32. A
macro is used so that instructions can be used as initializer elements.
Currently this does nothing, but it will allow for creating a data type
that can represent prefixed instructions.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
[mpe: Change include guard to _ASM_POWERPC_INST_H]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-7-jniethe5@gmail.com
When a program check exception happens while MMU translation is
disabled, following Oops happens in kprobe_handler() in the following
code:
} else if (*addr != BREAKPOINT_INSTRUCTION) {
BUG: Unable to handle kernel data access on read at 0x0000e268
Faulting instruction address: 0xc000ec34
Oops: Kernel access of bad area, sig: 11 [#1]
BE PAGE_SIZE=16K PREEMPT CMPC885
Modules linked in:
CPU: 0 PID: 429 Comm: cat Not tainted 5.6.0-rc1-s3k-dev-00824-g84195dc6c58a #3267
NIP: c000ec34 LR: c000ecd8 CTR: c019cab8
REGS: ca4d3b58 TRAP: 0300 Not tainted (5.6.0-rc1-s3k-dev-00824-g84195dc6c58a)
MSR: 00001032 <ME,IR,DR,RI> CR: 2a4d3c52 XER: 00000000
DAR: 0000e268 DSISR: c0000000
GPR00: c000b09c ca4d3c10 c66d0620 00000000 ca4d3c60 00000000 00009032 00000000
GPR08: 00020000 00000000 c087de44 c000afe0 c66d0ad0 100d3dd6 fffffff3 00000000
GPR16: 00000000 00000041 00000000 ca4d3d70 00000000 00000000 0000416d 00000000
GPR24: 00000004 c53b6128 00000000 0000e268 00000000 c07c0000 c07bb6fc ca4d3c60
NIP [c000ec34] kprobe_handler+0x128/0x290
LR [c000ecd8] kprobe_handler+0x1cc/0x290
Call Trace:
[ca4d3c30] [c000b09c] program_check_exception+0xbc/0x6fc
[ca4d3c50] [c000e43c] ret_from_except_full+0x0/0x4
--- interrupt: 700 at 0xe268
Instruction dump:
913e0008 81220000 38600001 3929ffff 91220000 80010024 bb410008 7c0803a6
38210020 4e800020 38600000 4e800020 <813b0000> 6d2a7fe0 2f8a0008 419e0154
---[ end trace 5b9152d4cdadd06d ]---
kprobe is not prepared to handle events in real mode and functions
running in real mode should have been blacklisted, so kprobe_handler()
can safely bail out telling 'this trap is not mine' for any trap that
happened while in real-mode.
If the trap happened with MSR_IR or MSR_DR cleared, return 0
immediately.
Reported-by: Larry Finger <Larry.Finger@lwfinger.net>
Fixes: 6cc89bad60 ("powerpc/kprobes: Invoke handlers directly")
Cc: stable@vger.kernel.org # v4.10+
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/424331e2006e7291a1bfe40e7f3fa58825f565e1.1582054578.git.christophe.leroy@c-s.fr
At the time being we have something like
if (something) {
p = get();
if (p) {
if (something_wrong)
goto out;
...
return;
} else if (a != b) {
if (some_error)
goto out;
...
}
goto out;
}
p = get();
if (!p) {
if (a != b) {
if (some_error)
goto out;
...
}
goto out;
}
This is similar to
p = get();
if (!p) {
if (a != b) {
if (some_error)
goto out;
...
}
goto out;
}
if (something) {
if (something_wrong)
goto out;
...
return;
}
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Reflow the comment that was moved]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/07a17425743600460ce35fa9432d42487a825583.1582099499.git.christophe.leroy@c-s.fr
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not write to the free software foundation inc
59 temple place suite 330 boston ma 02111 1307 usa
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 1334 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Clear current_kprobe and enable preemption in kprobe
even if pre_handler returns !0.
This simplifies function override using kprobes.
Jprobe used to require to keep the preemption disabled and
keep current_kprobe until it returned to original function
entry. For this reason kprobe_int3_handler() and similar
arch dependent kprobe handers checks pre_handler result
and exit without enabling preemption if the result is !0.
After removing the jprobe, Kprobes does not need to
keep preempt disabled even if user handler returns !0
anymore.
But since the function override handler in error-inject
and bpf is also returns !0 if it overrides a function,
to balancing the preempt count, it enables preemption
and reset current kprobe by itself.
That is a bad design that is very buggy. This fixes
such unbalanced preempt-count and current_kprobes setting
in kprobes, bpf and error-inject.
Note: for powerpc and x86, this removes all preempt_disable
from kprobe_ftrace_handler because ftrace callbacks are
called under preempt disabled.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: sparclinux@vger.kernel.org
Link: https://lore.kernel.org/lkml/152942494574.15209.12323837825873032258.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Don't call the ->break_handler() from the powerpc kprobes code,
because it was only used by jprobes which got removed.
This also removes skip_singlestep() and embeds it in the
caller, kprobe_ftrace_handler(), which simplifies regs->nip
operation around there.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-arch@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/lkml/152942477127.15209.8982613703787878618.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Remove arch dependent setjump/longjump functions
and unused fields in kprobe_ctlblk for jprobes
from arch/powerpc. This also reverts commits
related __is_active_jprobe() function.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-arch@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/lkml/152942445234.15209.12868722778364739753.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Michael Ellerman reported the following call trace when running
ftracetest:
BUG: using __this_cpu_write() in preemptible [00000000] code: ftracetest/6178
caller is opt_pre_handler+0xc4/0x110
CPU: 1 PID: 6178 Comm: ftracetest Not tainted 4.15.0-rc7-gcc6x-gb2cd1df #1
Call Trace:
[c0000000f9ec39c0] [c000000000ac4304] dump_stack+0xb4/0x100 (unreliable)
[c0000000f9ec3a00] [c00000000061159c] check_preemption_disabled+0x15c/0x170
[c0000000f9ec3a90] [c000000000217e84] opt_pre_handler+0xc4/0x110
[c0000000f9ec3af0] [c00000000004cf68] optimized_callback+0x148/0x170
[c0000000f9ec3b40] [c00000000004d954] optinsn_slot+0xec/0x10000
[c0000000f9ec3e30] [c00000000004bae0] kretprobe_trampoline+0x0/0x10
This is showing up since OPTPROBES is now enabled with CONFIG_PREEMPT.
trampoline_probe_handler() considers itself to be a special kprobe
handler for kretprobes. In doing so, it expects to be called from
kprobe_handler() on a trap, and re-enables preemption before returning a
non-zero return value so as to suppress any subsequent processing of the
trap by the kprobe_handler().
However, with optprobes, we don't deal with special handlers (we ignore
the return code) and just try to re-enable preemption causing the above
trace.
To address this, modify trampoline_probe_handler() to not be special.
The only additional processing done in kprobe_handler() is to emulate
the instruction (in this case, a 'nop'). We adjust the value of
regs->nip for the purpose and delegate the job of re-enabling
preemption and resetting current kprobe to the probe handlers
(kprobe_handler() or optimized_callback()).
Fixes: 8a2d71a3f2 ("powerpc/kprobes: Disable preemption before invoking probe handler for optprobes")
Cc: stable@vger.kernel.org # v4.15+
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Use safer string manipulation functions when dealing with a
user-provided string in kprobe_lookup_name().
Reported-by: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We have some dependencies & conflicts between patches in fixes and
things to go in next, both in the radix TLB flush code and the IMC PMU
driver. So merge fixes into next.
This makes the changes introduced in commit 83e840c770
("powerpc64/elfv1: Only dereference function descriptor for non-text
symbols") to be specific to the kprobe subsystem.
We previously changed ppc_function_entry() to always check the provided
address to confirm if it needed to be dereferenced. This is actually
only an issue for kprobe blacklisted asm labels (through use of
_ASM_NOKPROBE_SYMBOL) and can cause other issues with ftrace. Also, the
additional checks are not really necessary for our other uses.
As such, move this check to the kprobes subsystem.
Fixes: 83e840c770 ("powerpc64/elfv1: Only dereference function descriptor for non-text symbols")
Cc: stable@vger.kernel.org # v4.13+
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Fix a circa 2005 FIXME by implementing a check to ensure that we
actually got into the jprobe break handler() due to the trap in
jprobe_return().
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
In commit c05b8c4474 ("powerpc/kprobes: Skip livepatch_handler() for
jprobes"), we added a helper is_current_kprobe_addr() to help detect if
the modified regs->nip was due to a jprobe or livepatch. Masami felt
that the function name was not quite clear. To that end, this patch
renames is_current_kprobe_addr() to __is_active_jprobe() and adds a
comment to (hopefully) better clarify the purpose of this helper. The
helper has also now been moved to kprobes-ftrace.c so that it is only
available for KPROBES_ON_FTRACE.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Currently, we disable instruction emulation if emulate_step() fails for
any reason. However, such failures could be transient and specific to a
particular run. Instead, only disable instruction emulation if we have
never been able to emulate this. If we had emulated this instruction
successfully at least once, then we single step only this probe hit and
continue to try emulating the instruction in subsequent probe hits.
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
1. This is only used in kprobes.c, so make it static.
2. Remove the un-necessary (ret == 0) comparison in the else clause.
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Pull perf fixes from Thomas Gleixner:
"A couple of fixes for perf and kprobes:
- Add he missing exclude_kernel attribute for the precise_ip level so
!CAP_SYS_ADMIN users get the proper results.
- Warn instead of failing completely when perf has no unwind support
for a particular architectiure built in.
- Ensure that jprobes are at function entry and not at some random
place"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
kprobes: Ensure that jprobe probepoints are at function entry
kprobes: Simplify register_jprobes()
kprobes: Rename [arch_]function_offset_within_entry() to [arch_]kprobe_on_func_entry()
perf unwind: Do not fail due to missing unwind support
perf evsel: Set attr.exclude_kernel when probing max attr.precise_ip
Rename function_offset_within_entry() to scope it to kprobe namespace by
using kprobe_ prefix, and to also simplify it.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/3aa6c7e2e4fb6e00f3c24fa306496a66edb558ea.1499443367.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch_arm/disarm_probe() use direct assignment for copying
instructions, replace them with patch_instruction(). We don't need to
call flush_icache_range() because patch_instruction() does it for us.
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
ftrace_caller() depends on a modified regs->nip to detect if a certain
function has been livepatched. However, with KPROBES_ON_FTRACE, it is
possible for regs->nip to have been modified by the kprobes pre_handler
(jprobes, for instance). In this case, we do not want to invoke the
livepatch_handler so as not to consume the livepatch stack.
To distinguish between the two (kprobes and livepatch), we check if
there is an active kprobe on the current function. If there is, then we
know for sure that it must have modified the NIP as we don't support
livepatching a kprobe'd function. In this case, we simply skip the
livepatch_handler and branch to the new NIP. Otherwise, the
livepatch_handler is invoked.
Fixes: ead514d5fb ("powerpc/kprobes: Add support for KPROBES_ON_FTRACE")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This fixes a crash when function_graph and jprobes are used together.
This is essentially commit 237d28db03 ("ftrace/jprobes/x86: Fix
conflict between jprobes and function graph tracing"), but for powerpc.
Jprobes breaks function_graph tracing since the jprobe hook needs to use
jprobe_return(), which never returns back to the hook, but instead to
the original jprobe'd function. The solution is to momentarily pause
function_graph tracing before invoking the jprobe hook and re-enable it
when returning back to the original jprobe'd function.
Fixes: 6794c78243 ("powerpc64: port of the function graph tracer")
Cc: stable@vger.kernel.org # v2.6.30+
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
