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 <je...@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;
--
2.43.0
