Software stepping checks for the correct handler by iterating over a list
of dynamically registered handlers and calling all of them until one
handles the exception.
This is the only generic way to handle software stepping handlers in arm64
as the exception does not provide an immediate that could be checked,
contrary to software breakpoints.
However, the registration mechanism is not exported and has only
two current users : the KGDB stepping handler, and the uprobe single step
handler.
Given that one comes from user mode and the other from kernel mode, call
the appropriate one by checking the source EL of the exception.
Add a stand-in that returns DBG_HOOK_ERROR when the configuration
options are not enabled.
Remove `arch_init_uprobes()` as it is not useful anymore and is
specific to arm64.
Unify the naming of the handler to XXX_single_step_handler(), making it
clear they are related.
Signed-off-by: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Tested-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Reviewed-by: Will Deacon <will@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20250707114109.35672-5-ada.coupriediaz@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Software breakpoints pass an immediate value in ESR ("comment") that can
be used to call a specialized handler (KGDB, KASAN...).
We do so in two different ways :
- During early boot, `early_brk64` statically checks against known
immediates and calls the corresponding handler,
- During init, handlers are dynamically registered into a list. When
called, the generic software breakpoint handler will iterate over
the list to find the appropriate handler.
The dynamic registration does not provide any benefit here as it is not
exported and all its uses are within the arm64 tree. It also depends on an
RCU list, whose safe access currently relies on the non-preemptible state
of `do_debug_exception`.
Replace the list iteration logic in `call_break_hooks` to call
the breakpoint handlers statically if they are enabled, like in
`early_brk64`.
Expose the handlers in their respective headers to be reachable from
`arch/arm64/kernel/debug-monitors.c` at link time.
Unify the naming of the software breakpoint handlers to XXX_brk_handler(),
making it clear they are related and to differentiate from the
hardware breakpoints.
Signed-off-by: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Tested-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Reviewed-by: Will Deacon <will@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20250707114109.35672-4-ada.coupriediaz@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
* arm64/for-next/perf:
perf: Switch back to struct platform_driver::remove()
perf: arm_pmuv3: Add support for Samsung Mongoose PMU
dt-bindings: arm: pmu: Add Samsung Mongoose core compatible
perf/dwc_pcie: Fix typos in event names
perf/dwc_pcie: Add support for Ampere SoCs
ARM: pmuv3: Add missing write_pmuacr()
perf/marvell: Marvell PEM performance monitor support
perf/arm_pmuv3: Add PMUv3.9 per counter EL0 access control
perf/dwc_pcie: Convert the events with mixed case to lowercase
perf/cxlpmu: Support missing events in 3.1 spec
perf: imx_perf: add support for i.MX91 platform
dt-bindings: perf: fsl-imx-ddr: Add i.MX91 compatible
drivers perf: remove unused field pmu_node
* for-next/gcs: (42 commits)
: arm64 Guarded Control Stack user-space support
kselftest/arm64: Fix missing printf() argument in gcs/gcs-stress.c
arm64/gcs: Fix outdated ptrace documentation
kselftest/arm64: Ensure stable names for GCS stress test results
kselftest/arm64: Validate that GCS push and write permissions work
kselftest/arm64: Enable GCS for the FP stress tests
kselftest/arm64: Add a GCS stress test
kselftest/arm64: Add GCS signal tests
kselftest/arm64: Add test coverage for GCS mode locking
kselftest/arm64: Add a GCS test program built with the system libc
kselftest/arm64: Add very basic GCS test program
kselftest/arm64: Always run signals tests with GCS enabled
kselftest/arm64: Allow signals tests to specify an expected si_code
kselftest/arm64: Add framework support for GCS to signal handling tests
kselftest/arm64: Add GCS as a detected feature in the signal tests
kselftest/arm64: Verify the GCS hwcap
arm64: Add Kconfig for Guarded Control Stack (GCS)
arm64/ptrace: Expose GCS via ptrace and core files
arm64/signal: Expose GCS state in signal frames
arm64/signal: Set up and restore the GCS context for signal handlers
arm64/mm: Implement map_shadow_stack()
...
* for-next/probes:
: Various arm64 uprobes/kprobes cleanups
arm64: insn: Simulate nop instruction for better uprobe performance
arm64: probes: Remove probe_opcode_t
arm64: probes: Cleanup kprobes endianness conversions
arm64: probes: Move kprobes-specific fields
arm64: probes: Fix uprobes for big-endian kernels
arm64: probes: Fix simulate_ldr*_literal()
arm64: probes: Remove broken LDR (literal) uprobe support
* for-next/asm-offsets:
: arm64 asm-offsets.c cleanup (remove unused offsets)
arm64: asm-offsets: remove PREEMPT_DISABLE_OFFSET
arm64: asm-offsets: remove DMA_{TO,FROM}_DEVICE
arm64: asm-offsets: remove VM_EXEC and PAGE_SZ
arm64: asm-offsets: remove MM_CONTEXT_ID
arm64: asm-offsets: remove COMPAT_{RT_,SIGFRAME_REGS_OFFSET
arm64: asm-offsets: remove VMA_VM_*
arm64: asm-offsets: remove TSK_ACTIVE_MM
* for-next/tlb:
: TLB flushing optimisations
arm64: optimize flush tlb kernel range
arm64: tlbflush: add __flush_tlb_range_limit_excess()
* for-next/misc:
: Miscellaneous patches
arm64: tls: Fix context-switching of tpidrro_el0 when kpti is enabled
arm64/ptrace: Clarify documentation of VL configuration via ptrace
acpi/arm64: remove unnecessary cast
arm64/mm: Change protval as 'pteval_t' in map_range()
arm64: uprobes: Optimize cache flushes for xol slot
acpi/arm64: Adjust error handling procedure in gtdt_parse_timer_block()
arm64: fix .data.rel.ro size assertion when CONFIG_LTO_CLANG
arm64/ptdump: Test both PTE_TABLE_BIT and PTE_VALID for block mappings
arm64/mm: Sanity check PTE address before runtime P4D/PUD folding
arm64/mm: Drop setting PTE_TYPE_PAGE in pte_mkcont()
ACPI: GTDT: Tighten the check for the array of platform timer structures
arm64/fpsimd: Fix a typo
arm64: Expose ID_AA64ISAR1_EL1.XS to sanitised feature consumers
arm64: Return early when break handler is found on linked-list
arm64/mm: Re-organize arch_make_huge_pte()
arm64/mm: Drop _PROT_SECT_DEFAULT
arm64: Add command-line override for ID_AA64MMFR0_EL1.ECV
arm64: head: Drop SWAPPER_TABLE_SHIFT
arm64: cpufeature: add POE to cpucap_is_possible()
arm64/mm: Change pgattr_change_is_safe() arguments as pteval_t
* for-next/mte:
: Various MTE improvements
selftests: arm64: add hugetlb mte tests
hugetlb: arm64: add mte support
* for-next/sysreg:
: arm64 sysreg updates
arm64/sysreg: Update ID_AA64MMFR1_EL1 to DDI0601 2024-09
* for-next/stacktrace:
: arm64 stacktrace improvements
arm64: preserve pt_regs::stackframe during exec*()
arm64: stacktrace: unwind exception boundaries
arm64: stacktrace: split unwind_consume_stack()
arm64: stacktrace: report recovered PCs
arm64: stacktrace: report source of unwind data
arm64: stacktrace: move dump_backtrace() to kunwind_stack_walk()
arm64: use a common struct frame_record
arm64: pt_regs: swap 'unused' and 'pmr' fields
arm64: pt_regs: rename "pmr_save" -> "pmr"
arm64: pt_regs: remove stale big-endian layout
arm64: pt_regs: assert pt_regs is a multiple of 16 bytes
* for-next/hwcap3:
: Add AT_HWCAP3 support for arm64 (also wire up AT_HWCAP4)
arm64: Support AT_HWCAP3
binfmt_elf: Wire up AT_HWCAP3 at AT_HWCAP4
* for-next/kselftest: (30 commits)
: arm64 kselftest fixes/cleanups
kselftest/arm64: Try harder to generate different keys during PAC tests
kselftest/arm64: Don't leak pipe fds in pac.exec_sign_all()
kselftest/arm64: Corrupt P0 in the irritator when testing SSVE
kselftest/arm64: Add FPMR coverage to fp-ptrace
kselftest/arm64: Expand the set of ZA writes fp-ptrace does
kselftets/arm64: Use flag bits for features in fp-ptrace assembler code
kselftest/arm64: Enable build of PAC tests with LLVM=1
kselftest/arm64: Check that SVCR is 0 in signal handlers
kselftest/arm64: Fix printf() compiler warnings in the arm64 syscall-abi.c tests
kselftest/arm64: Fix printf() warning in the arm64 MTE prctl() test
kselftest/arm64: Fix printf() compiler warnings in the arm64 fp tests
kselftest/arm64: Fix build with stricter assemblers
kselftest/arm64: Test signal handler state modification in fp-stress
kselftest/arm64: Provide a SIGUSR1 handler in the kernel mode FP stress test
kselftest/arm64: Implement irritators for ZA and ZT
kselftest/arm64: Remove unused ADRs from irritator handlers
kselftest/arm64: Correct misleading comments on fp-stress irritators
kselftest/arm64: Poll less often while waiting for fp-stress children
kselftest/arm64: Increase frequency of signal delivery in fp-stress
kselftest/arm64: Fix encoding for SVE B16B16 test
...
* for-next/crc32:
: Optimise CRC32 using PMULL instructions
arm64/crc32: Implement 4-way interleave using PMULL
arm64/crc32: Reorganize bit/byte ordering macros
arm64/lib: Handle CRC-32 alternative in C code
* for-next/guest-cca:
: Support for running Linux as a guest in Arm CCA
arm64: Document Arm Confidential Compute
virt: arm-cca-guest: TSM_REPORT support for realms
arm64: Enable memory encrypt for Realms
arm64: mm: Avoid TLBI when marking pages as valid
arm64: Enforce bounce buffers for realm DMA
efi: arm64: Map Device with Prot Shared
arm64: rsi: Map unprotected MMIO as decrypted
arm64: rsi: Add support for checking whether an MMIO is protected
arm64: realm: Query IPA size from the RMM
arm64: Detect if in a realm and set RIPAS RAM
arm64: rsi: Add RSI definitions
* for-next/haft:
: Support for arm64 FEAT_HAFT
arm64: pgtable: Warn unexpected pmdp_test_and_clear_young()
arm64: Enable ARCH_HAS_NONLEAF_PMD_YOUNG
arm64: Add support for FEAT_HAFT
arm64: setup: name 'tcr2' register
arm64/sysreg: Update ID_AA64MMFR1_EL1 register
* for-next/scs:
: Dynamic shadow call stack fixes
arm64/scs: Drop unused prototype __pi_scs_patch_vmlinux()
arm64/scs: Deal with 64-bit relative offsets in FDE frames
arm64/scs: Fix handling of DWARF augmentation data in CIE/FDE frames
The profiling of single-thread selftests bench reveals a bottlenect in
caches_clean_inval_pou() on ARM64. On my local testing machine, this
function takes approximately 34% of CPU cycles for trig-uprobe-nop and
trig-uprobe-push.
This patch add a check to avoid unnecessary cache flush when writing
instruction to the xol slot. If the instruction is same with the
existing instruction in slot, there is no need to synchronize D/I cache.
Since xol slot allocation and updates occur on the hot path of uprobe
handling, The upstream kernel running on Kunpeng916 (Hi1616), 4 NUMA
nodes, 64 cores@ 2.4GHz reveals this optimization has obvious gain for
nop and push testcases.
Before (next-20240918)
----------------------
uprobe-nop ( 1 cpus): 0.418 ± 0.001M/s ( 0.418M/s/cpu)
uprobe-push ( 1 cpus): 0.411 ± 0.005M/s ( 0.411M/s/cpu)
uprobe-ret ( 1 cpus): 2.052 ± 0.002M/s ( 2.052M/s/cpu)
uretprobe-nop ( 1 cpus): 0.350 ± 0.000M/s ( 0.350M/s/cpu)
uretprobe-push ( 1 cpus): 0.353 ± 0.000M/s ( 0.353M/s/cpu)
uretprobe-ret ( 1 cpus): 1.074 ± 0.001M/s ( 1.074M/s/cpu)
After
-----
uprobe-nop ( 1 cpus): 0.926 ± 0.000M/s ( 0.926M/s/cpu)
uprobe-push ( 1 cpus): 0.910 ± 0.001M/s ( 0.910M/s/cpu)
uprobe-ret ( 1 cpus): 2.056 ± 0.001M/s ( 2.056M/s/cpu)
uretprobe-nop ( 1 cpus): 0.653 ± 0.001M/s ( 0.653M/s/cpu)
uretprobe-push ( 1 cpus): 0.645 ± 0.000M/s ( 0.645M/s/cpu)
uretprobe-ret ( 1 cpus): 1.093 ± 0.001M/s ( 1.093M/s/cpu)
Signed-off-by: Liao Chang <liaochang1@huawei.com>
Link: https://lore.kernel.org/r/20240919121719.2148361-1-liaochang1@huawei.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The probe_opcode_t typedef for u32 isn't necessary, and is a source of
confusion as it is easily confused with kprobe_opcode_t, which is a
typedef for __le32.
The typedef is only used within arch/arm64, and all of arm64's commn
insn code uses u32 for the endian-agnostic value of an instruction, so
it'd be clearer to use u32 consistently.
Remove probe_opcode_t and use u32 directly.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marnias@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20241008155851.801546-7-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The arm64 uprobes code is broken for big-endian kernels as it doesn't
convert the in-memory instruction encoding (which is always
little-endian) into the kernel's native endianness before analyzing and
simulating instructions. This may result in a few distinct problems:
* The kernel may may erroneously reject probing an instruction which can
safely be probed.
* The kernel may erroneously erroneously permit stepping an
instruction out-of-line when that instruction cannot be stepped
out-of-line safely.
* The kernel may erroneously simulate instruction incorrectly dur to
interpretting the byte-swapped encoding.
The endianness mismatch isn't caught by the compiler or sparse because:
* The arch_uprobe::{insn,ixol} fields are encoded as arrays of u8, so
the compiler and sparse have no idea these contain a little-endian
32-bit value. The core uprobes code populates these with a memcpy()
which similarly does not handle endianness.
* While the uprobe_opcode_t type is an alias for __le32, both
arch_uprobe_analyze_insn() and arch_uprobe_skip_sstep() cast from u8[]
to the similarly-named probe_opcode_t, which is an alias for u32.
Hence there is no endianness conversion warning.
Fix this by changing the arch_uprobe::{insn,ixol} fields to __le32 and
adding the appropriate __le32_to_cpu() conversions prior to consuming
the instruction encoding. The core uprobes copies these fields as opaque
ranges of bytes, and so is unaffected by this change.
At the same time, remove MAX_UINSN_BYTES and consistently use
AARCH64_INSN_SIZE for clarity.
Tested with the following:
| #include <stdio.h>
| #include <stdbool.h>
|
| #define noinline __attribute__((noinline))
|
| static noinline void *adrp_self(void)
| {
| void *addr;
|
| asm volatile(
| " adrp %x0, adrp_self\n"
| " add %x0, %x0, :lo12:adrp_self\n"
| : "=r" (addr));
| }
|
|
| int main(int argc, char *argv)
| {
| void *ptr = adrp_self();
| bool equal = (ptr == adrp_self);
|
| printf("adrp_self => %p\n"
| "adrp_self() => %p\n"
| "%s\n",
| adrp_self, ptr, equal ? "EQUAL" : "NOT EQUAL");
|
| return 0;
| }
.... where the adrp_self() function was compiled to:
| 00000000004007e0 <adrp_self>:
| 4007e0: 90000000 adrp x0, 400000 <__ehdr_start>
| 4007e4: 911f8000 add x0, x0, #0x7e0
| 4007e8: d65f03c0 ret
Before this patch, the ADRP is not recognized, and is assumed to be
steppable, resulting in corruption of the result:
| # ./adrp-self
| adrp_self => 0x4007e0
| adrp_self() => 0x4007e0
| EQUAL
| # echo 'p /root/adrp-self:0x007e0' > /sys/kernel/tracing/uprobe_events
| # echo 1 > /sys/kernel/tracing/events/uprobes/enable
| # ./adrp-self
| adrp_self => 0x4007e0
| adrp_self() => 0xffffffffff7e0
| NOT EQUAL
After this patch, the ADRP is correctly recognized and simulated:
| # ./adrp-self
| adrp_self => 0x4007e0
| adrp_self() => 0x4007e0
| EQUAL
| #
| # echo 'p /root/adrp-self:0x007e0' > /sys/kernel/tracing/uprobe_events
| # echo 1 > /sys/kernel/tracing/events/uprobes/enable
| # ./adrp-self
| adrp_self => 0x4007e0
| adrp_self() => 0x4007e0
| EQUAL
Fixes: 9842ceae9f ("arm64: Add uprobe support")
Cc: stable@vger.kernel.org
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20241008155851.801546-4-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
In the initial release of the ARM Architecture Reference Manual for
ARMv8-A, the ESR_ELx registers were defined as 32-bit registers. This
changed in 2018 with version D.a (ARM DDI 0487D.a) of the architecture,
when they became 64-bit registers, with bits [63:32] defined as RES0. In
version G.a, a new field was added to ESR_ELx, ISS2, which covers bits
[36:32]. This field is used when the Armv8.7 extension FEAT_LS64 is
implemented.
As a result of the evolution of the register width, Linux stores it as
both a 64-bit value and a 32-bit value, which hasn't affected correctness
so far as Linux only uses the lower 32 bits of the register.
Make the register type consistent and always treat it as 64-bit wide. The
register is redefined as an "unsigned long", which is an unsigned
double-word (64-bit quantity) for the LP64 machine (aapcs64 [1], Table 1,
page 14). The type was chosen because "unsigned int" is the most frequent
type for ESR_ELx and because FAR_ELx, which is used together with ESR_ELx
in exception handling, is also declared as "unsigned long". The 64-bit type
also makes adding support for architectural features that use fields above
bit 31 easier in the future.
The KVM hypervisor will receive a similar update in a subsequent patch.
[1] https://github.com/ARM-software/abi-aa/releases/download/2021Q3/aapcs64.pdf
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220425114444.368693-4-alexandru.elisei@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
To be consistent with other functions with similar names and
functionality in cacheflush.h, cache.S, and cachetlb.rst, change
to specify the range in terms of start and end, as opposed to
start and size.
No functional change intended.
Reported-by: Will Deacon <will@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20210524083001.2586635-17-tabba@google.com
Signed-off-by: Will Deacon <will@kernel.org>
As stated in linux/errno.h, ENOTSUPP should never be seen by user programs.
When we set up uprobe with 32-bit perf and arm64 kernel, we would see the
following vague error without useful hint.
The sys_perf_event_open() syscall returned with 524 (INTERNAL ERROR:
strerror_r(524, [buf], 128)=22)
Use EOPNOTSUPP instead to indicate such cases.
Signed-off-by: He Zhe <zhe.he@windriver.com>
Link: https://lore.kernel.org/r/20210223082535.48730-1-zhe.he@windriver.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Based on 2 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 version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kprobes and uprobes reserve some BRK immediates for installing their
probes. Define these along with the other reservations in brk-imm.h
and rename the ESR definitions to be consistent with the others that we
already have.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Now that the debug hook dispatching code takes the triggering exception
level into account, there's no need for the hooks themselves to poke
around with user_mode(regs).
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Mixing kernel and user debug hooks together is highly error-prone as it
relies on all of the hooks to figure out whether the exception came from
kernel or user, and then to act accordingly.
Make our debug hook code a little more robust by maintaining separate
hook lists for user and kernel, with separate registration functions
to force callers to be explicit about the exception levels that they
care about.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Currently mm->context.flags field uses thread_info flags which is not
the best idea for many reasons. For example, mm_context_t doesn't need
most of thread_info flags. And it would be difficult to add new mm-related
flag if needed because it may easily interfere with TIF ones.
To deal with it, the new MMCF_AARCH32 flag is introduced for
mm_context_t->flags, where MMCF prefix stands for mm_context_t flags.
Also, mm_context_t flag doesn't require atomicity and ordering of the
access, so using set/clear_bit() is replaced with simple masks.
Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This patch adds support for uprobe on ARM64 architecture.
Unit tests for following have been done so far and they have been found
working
1. Step-able instructions, like sub, ldr, add etc.
2. Simulation-able like ret, cbnz, cbz etc.
3. uretprobe
4. Reject-able instructions like sev, wfe etc.
5. trapped and abort xol path
6. probe at unaligned user address.
7. longjump test cases
Currently it does not support aarch32 instruction probing.
Signed-off-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
