Hi Guo, On Mon, 13 Jul 2020 23:39:15 +0000 guo...@kernel.org wrote:
> From: Guo Ren <guo...@linux.alibaba.com> > > The patchset includes kprobe/uprobe support and some related fixups. > Patrick provides HAVE_REGS_AND_STACK_ACCESS_API support and some > kprobe's code. The framework of k/uprobe is from csky but also refers > to other arches'. kprobes on ftrace is also supported in the patchset. > > There is no single step exception in riscv ISA, only single-step > facility for jtag. See riscv-Privileged spec: > > Interrupt Exception Code-Description > 1 0 Reserved > 1 1 Supervisor software interrupt > 1 2–4 Reserved > 1 5 Supervisor timer interrupt > 1 6–8 Reserved > 1 9 Supervisor external interrupt > 1 10–15 Reserved > 1 ≥16 Available for platform use > 0 0 Instruction address misaligned > 0 1 Instruction access fault > 0 2 Illegal instruction > 0 3 Breakpoint > 0 4 Load address misaligned > 0 5 Load access fault > 0 6 Store/AMO address misaligned > 0 7 Store/AMO access fault > 0 8 Environment call from U-mode > 0 9 Environment call from S-mode > 0 10–11 Reserved > 0 12 Instruction page fault > 0 13 Load page fault > 0 14 Reserved > 0 15 Store/AMO page fault > 0 16–23 Reserved > 0 24–31 Available for custom use > 0 32–47 Reserved > 0 48–63 Available for custom use > 0 ≥64 Reserved > > No single step! > > Other arches use hardware single-step exception for k/uprobe, eg: > - powerpc: regs->msr |= MSR_SINGLESTEP > - arm/arm64: PSTATE.D for enabling software step exceptions > - s390: Set PER control regs, turns on single step for the given address > - x86: regs->flags |= X86_EFLAGS_TF > - csky: of course use hw single step :) > > All the above arches use a hardware single-step exception > mechanism to execute the instruction that was replaced with a probe > breakpoint. So utilize ebreak to simulate. > > Some pc related instructions couldn't be executed out of line and some > system/fence instructions couldn't be a trace site at all. So we give > out a reject list and simulate list in decode-insn.c. > > You could use uprobe to test simulate code like this: > > echo 'p:enter_current_state_one /hello:0x6e4 a0=%a0 a1=%a1' >> > /sys/kernel/debug/tracing/uprobe_events > echo 1 > /sys/kernel/debug/tracing/events/uprobes/enable > /hello > ^C > cat /sys/kernel/debug/tracing/trace > tracer: nop > > entries-in-buffer/entries-written: 1/1 #P:1 > > _-----=> irqs-off > / _----=> need-resched > | / _---=> hardirq/softirq > || / _--=> preempt-depth > ||| / delay > TASK-PID CPU# |||| TIMESTAMP FUNCTION > | | | |||| | | > hello-94 [000] d... 55.404242: enter_current_state_one: > (0x106e4) a0=0x1 a1=0x3fffa8ada8 > > Be care /hello:0x6e4 is the file offset in elf and it relate to 0x106e4 > in memory and hello is your target elf program. > > Try kprobe like this: > > echo 'p:myprobe _do_fork dfd=%a0 filename=%a1 flags=%a2 mode=+4($stack)' > > /sys/kernel/debug/tracing/kprobe_events > echo 'r:myretprobe _do_fork $retval' >> > /sys/kernel/debug/tracing/kprobe_event > > echo 1 >/sys/kernel/debug/tracing/events/kprobes/enable > cat /sys/kernel/debug/tracing/trace > tracer: nop > > entries-in-buffer/entries-written: 2/2 #P:1 > > _-----=> irqs-off > / _----=> need-resched > | / _---=> hardirq/softirq > || / _--=> preempt-depth > ||| / delay > TASK-PID CPU# |||| TIMESTAMP FUNCTION > | | | |||| | | > sh-92 [000] .n.. 131.804230: myprobe: (_do_fork+0x0/0x2e6) > dfd=0xffffffe03929fdf8 filename=0x0 flags=0x101000 mode=0x1200000ffffffe0 > sh-92 [000] d... 131.806607: myretprobe: > (__do_sys_clone+0x70/0x82 <- _do_fork) arg1=0x5f > cat /sys/kernel/debug/tracing/trace Thank you for your great work! BTW, could you also run the ftracetest and boot-time smoke test on it? You can find it under tools/testing/selftests/ftrace, and CONFIG_KPROBES_SANITY_TEST. It will ensure that your patch is correctly ported. Thank you, > > Changlog v3: > - Add upport for function error injection > - Fixup kprobes handler couldn't change pc > > Changlog v2: > - Add Reviewed-by, Tested-by, Acked-by, thx for all of you > - Add kprobes on ftrace feature > - Use __always_inline as same as fix_to_virt for fixup > BUILD_BUG_ON > - Use const "const unsigned int" for 2th param for fixup > BUILD_BUG_ON > > Guo Ren (6): > riscv: Fixup compile error BUILD_BUG_ON failed > riscv: Fixup kprobes handler couldn't change pc > riscv: Add kprobes supported > riscv: Add uprobes supported > riscv: Add KPROBES_ON_FTRACE supported > riscv: Add support for function error injection > > Patrick Stählin (1): > RISC-V: Implement ptrace regs and stack API > > arch/riscv/Kconfig | 8 + > arch/riscv/include/asm/kprobes.h | 40 +++ > arch/riscv/include/asm/probes.h | 24 ++ > arch/riscv/include/asm/processor.h | 1 + > arch/riscv/include/asm/ptrace.h | 35 ++ > arch/riscv/include/asm/thread_info.h | 4 +- > arch/riscv/include/asm/uprobes.h | 40 +++ > arch/riscv/kernel/Makefile | 1 + > arch/riscv/kernel/mcount-dyn.S | 3 +- > arch/riscv/kernel/patch.c | 8 +- > arch/riscv/kernel/probes/Makefile | 6 + > arch/riscv/kernel/probes/decode-insn.c | 48 +++ > arch/riscv/kernel/probes/decode-insn.h | 18 + > arch/riscv/kernel/probes/ftrace.c | 52 +++ > arch/riscv/kernel/probes/kprobes.c | 471 > ++++++++++++++++++++++++++ > arch/riscv/kernel/probes/kprobes_trampoline.S | 93 +++++ > arch/riscv/kernel/probes/simulate-insn.c | 85 +++++ > arch/riscv/kernel/probes/simulate-insn.h | 47 +++ > arch/riscv/kernel/probes/uprobes.c | 186 ++++++++++ > arch/riscv/kernel/ptrace.c | 99 ++++++ > arch/riscv/kernel/signal.c | 3 + > arch/riscv/kernel/traps.c | 19 ++ > arch/riscv/lib/Makefile | 2 + > arch/riscv/lib/error-inject.c | 10 + > arch/riscv/mm/fault.c | 11 + > 25 files changed, 1310 insertions(+), 4 deletions(-) > create mode 100644 arch/riscv/include/asm/probes.h > create mode 100644 arch/riscv/include/asm/uprobes.h > create mode 100644 arch/riscv/kernel/probes/Makefile > create mode 100644 arch/riscv/kernel/probes/decode-insn.c > create mode 100644 arch/riscv/kernel/probes/decode-insn.h > create mode 100644 arch/riscv/kernel/probes/ftrace.c > create mode 100644 arch/riscv/kernel/probes/kprobes.c > create mode 100644 arch/riscv/kernel/probes/kprobes_trampoline.S > create mode 100644 arch/riscv/kernel/probes/simulate-insn.c > create mode 100644 arch/riscv/kernel/probes/simulate-insn.h > create mode 100644 arch/riscv/kernel/probes/uprobes.c > create mode 100644 arch/riscv/lib/error-inject.c > > -- > 2.7.4 > -- Masami Hiramatsu <mhira...@kernel.org>
