Add ability to setup hw breakpoints to ptrace. Call defines a new structure of __riscv_hwdebug_state which will be passed to ptrace.
Signed-off-by: Jesse Taube jesse@rivosinc.com --- RFC -> V1: - Add struct __riscv_hwdebug_state for ptrace_hbp_set/get - Break out ptrace_hbp_set/get so regset can use them - Check for NULL instead of IS_ERR_OR_NULL - Move ptrace_get/sethbpregs above user_regset V1 -> V2: - No change --- arch/riscv/include/asm/processor.h | 4 + arch/riscv/include/uapi/asm/ptrace.h | 9 +++ arch/riscv/kernel/hw_breakpoint.c | 14 +++- arch/riscv/kernel/process.c | 4 + arch/riscv/kernel/ptrace.c | 110 +++++++++++++++++++++++++++ 5 files changed, 140 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h index 5f56eb9d114a..488d956a951f 100644 --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -12,6 +12,7 @@
#include <vdso/processor.h>
+#include <asm/hw_breakpoint.h> #include <asm/ptrace.h>
#define arch_get_mmap_end(addr, len, flags) \ @@ -108,6 +109,9 @@ struct thread_struct { struct __riscv_v_ext_state vstate; unsigned long align_ctl; struct __riscv_v_ext_state kernel_vstate; +#ifdef CONFIG_HAVE_HW_BREAKPOINT + struct perf_event *ptrace_bps[RV_MAX_TRIGGERS]; +#endif #ifdef CONFIG_SMP /* Flush the icache on migration */ bool force_icache_flush; diff --git a/arch/riscv/include/uapi/asm/ptrace.h b/arch/riscv/include/uapi/asm/ptrace.h index a38268b19c3d..20d1aa595cbd 100644 --- a/arch/riscv/include/uapi/asm/ptrace.h +++ b/arch/riscv/include/uapi/asm/ptrace.h @@ -14,6 +14,8 @@
#define PTRACE_GETFDPIC_EXEC 0 #define PTRACE_GETFDPIC_INTERP 1 +#define PTRACE_GETHBPREGS 2 +#define PTRACE_SETHBPREGS 3
/* * User-mode register state for core dumps, ptrace, sigcontext @@ -120,6 +122,13 @@ struct __riscv_v_regset_state { char vreg[]; };
+struct __riscv_hwdebug_state { + unsigned long addr; + unsigned long type; + unsigned long len; + unsigned long ctrl; +} __packed; + /* * According to spec: The number of bits in a single vector register, * VLEN >= ELEN, which must be a power of 2, and must be no greater than diff --git a/arch/riscv/kernel/hw_breakpoint.c b/arch/riscv/kernel/hw_breakpoint.c index f12306247436..f8841941f2ab 100644 --- a/arch/riscv/kernel/hw_breakpoint.c +++ b/arch/riscv/kernel/hw_breakpoint.c @@ -715,7 +715,19 @@ void arch_uninstall_hw_breakpoint(struct perf_event *event) pr_warn("%s: Failed to uninstall trigger %d. error: %ld\n", __func__, i, ret.error); }
-void flush_ptrace_hw_breakpoint(struct task_struct *tsk) { } +/* + * Release the user breakpoints used by ptrace + */ +void flush_ptrace_hw_breakpoint(struct task_struct *tsk) +{ + int i; + struct thread_struct *t = &tsk->thread; + + for (i = 0; i < dbtr_total_num; i++) { + unregister_hw_breakpoint(t->ptrace_bps[i]); + t->ptrace_bps[i] = NULL; + } +}
void hw_breakpoint_pmu_read(struct perf_event *bp) { }
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 15d8f75902f8..9cf07ecfb523 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -9,6 +9,7 @@
#include <linux/bitfield.h> #include <linux/cpu.h> +#include <linux/hw_breakpoint.h> #include <linux/kernel.h> #include <linux/sched.h> #include <linux/sched/debug.h> @@ -164,6 +165,7 @@ void start_thread(struct pt_regs *regs, unsigned long pc,
void flush_thread(void) { + flush_ptrace_hw_breakpoint(current); #ifdef CONFIG_FPU /* * Reset FPU state and context @@ -218,6 +220,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) set_bit(MM_CONTEXT_LOCK_PMLEN, &p->mm->context.flags);
memset(&p->thread.s, 0, sizeof(p->thread.s)); + if (IS_ENABLED(CONFIG_HAVE_HW_BREAKPOINT)) + memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
/* p->thread holds context to be restored by __switch_to() */ if (unlikely(args->fn)) { diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c index ea67e9fb7a58..e097e6a61910 100644 --- a/arch/riscv/kernel/ptrace.c +++ b/arch/riscv/kernel/ptrace.c @@ -9,11 +9,13 @@
#include <asm/vector.h> #include <asm/ptrace.h> +#include <asm/hw_breakpoint.h> #include <asm/syscall.h> #include <asm/thread_info.h> #include <asm/switch_to.h> #include <linux/audit.h> #include <linux/compat.h> +#include <linux/hw_breakpoint.h> #include <linux/ptrace.h> #include <linux/elf.h> #include <linux/regset.h> @@ -184,6 +186,104 @@ static int tagged_addr_ctrl_set(struct task_struct *target, } #endif
+#ifdef CONFIG_HAVE_HW_BREAKPOINT +static void ptrace_hbptriggered(struct perf_event *bp, + struct perf_sample_data *data, + struct pt_regs *regs) +{ + struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp); + int num = 0; + + force_sig_ptrace_errno_trap(num, (void __user *)bkpt->address); +} + +static int ptrace_hbp_get(struct task_struct *child, unsigned long idx, + struct __riscv_hwdebug_state *state) +{ + struct perf_event *bp; + + if (idx >= RV_MAX_TRIGGERS) + return -EINVAL; + + bp = child->thread.ptrace_bps[idx]; + + if (!bp) + return -ENOENT; + + state->addr = bp->attr.bp_addr; + state->len = bp->attr.bp_len; + state->type = bp->attr.bp_type; + state->ctrl = bp->attr.disabled == 1; + + return 0; +} + +static int ptrace_hbp_set(struct task_struct *child, unsigned long idx, + struct __riscv_hwdebug_state *state) +{ + struct perf_event *bp; + struct perf_event_attr attr; + + if (idx >= RV_MAX_TRIGGERS) + return -EINVAL; + + bp = child->thread.ptrace_bps[idx]; + if (bp) + attr = bp->attr; + else + ptrace_breakpoint_init(&attr); + + attr.bp_addr = state->addr; + attr.bp_len = state->len; + attr.bp_type = state->type; + attr.disabled = state->ctrl == 1; + + if (!bp) { + bp = register_user_hw_breakpoint(&attr, ptrace_hbptriggered, NULL, + child); + if (IS_ERR(bp)) + return PTR_ERR(bp); + + child->thread.ptrace_bps[idx] = bp; + return 0; + } + + return modify_user_hw_breakpoint(bp, &attr); +} + +/* + * idx selects the breakpoint index. + * Both PTRACE_GETHBPREGS and PTRACE_SETHBPREGS transfer __riscv_hwdebug_state + */ + +static long ptrace_gethbpregs(struct task_struct *child, unsigned long idx, + unsigned long __user *datap) +{ + struct __riscv_hwdebug_state state; + long ret; + + ret = ptrace_hbp_get(child, idx, &state); + if (ret) + return ret; + if (copy_to_user(datap, &state, sizeof(state))) + return -EFAULT; + + return 0; +} + +static long ptrace_sethbpregs(struct task_struct *child, unsigned long idx, + unsigned long __user *datap) +{ + struct __riscv_hwdebug_state state; + + if (copy_from_user(&state, datap, sizeof(state))) + return -EFAULT; + + return ptrace_hbp_set(child, idx, &state); + +} +#endif + static const struct user_regset riscv_user_regset[] = { [REGSET_X] = { .core_note_type = NT_PRSTATUS, @@ -340,8 +440,18 @@ long arch_ptrace(struct task_struct *child, long request, unsigned long addr, unsigned long data) { long ret = -EIO; + unsigned long __user *datap = (unsigned long __user *) data;
switch (request) { +#ifdef CONFIG_HAVE_HW_BREAKPOINT + case PTRACE_GETHBPREGS: + ret = ptrace_gethbpregs(child, addr, datap); + break; + + case PTRACE_SETHBPREGS: + ret = ptrace_sethbpregs(child, addr, datap); + break; +#endif default: ret = ptrace_request(child, request, addr, data); break;