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Subject[Patch 6/6] MIPS: Ptrace support for HARDWARE_WATCHPOINTS

This is the final part of the watch register patch. Here we hook up
ptrace so that the user space debugger (gdb), can set and read the
registers.

Signed-off-by: David Daney <ddaney@avtrex.com>
---
arch/mips/kernel/ptrace.c | 97 ++++++++++++++++++++++++++++++++++++++++++-
arch/mips/kernel/ptrace32.c | 15 +++++++
include/asm-mips/ptrace.h | 31 ++++++++++++++
3 files changed, 142 insertions(+), 1 deletions(-)

diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 35234b9..d12f2d4 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -46,7 +46,8 @@
*/
void ptrace_disable(struct task_struct *child)
{
- /* Nothing to do.. */
+ /* Don't load the watchpoint registers for the ex-child. */
+ clear_tsk_thread_flag(child, TIF_LOAD_WATCH);
}

/*
@@ -167,6 +168,90 @@ int ptrace_setfpregs(struct task_struct *child, __u32 __user *data)
return 0;
}

+int ptrace_get_watch_regs(struct task_struct *child,
+ struct pt_watch_regs __user *addr)
+{
+ enum pt_watch_style style;
+ int i;
+
+ if (!cpu_has_watch || current_cpu_data.watch_reg_use_cnt == 0)
+ return -EIO;
+ if (!access_ok(VERIFY_WRITE, addr, sizeof(struct pt_watch_regs)))
+ return -EIO;
+
+#ifdef CONFIG_32BIT
+ style = pt_watch_style_mips32;
+#define WATCH_STYLE mips32
+#else
+ style = pt_watch_style_mips64;
+#define WATCH_STYLE mips64
+#endif
+
+ __put_user(style, &addr->style);
+ __put_user(current_cpu_data.watch_reg_use_cnt,
+ &addr->WATCH_STYLE.num_valid);
+ __put_user(current_cpu_data.watch_reg_mask,
+ &addr->WATCH_STYLE.reg_mask);
+ __put_user(current_cpu_data.watch_reg_irw,
+ &addr->WATCH_STYLE.irw_mask);
+ for (i = 0; i < current_cpu_data.watch_reg_use_cnt; i++) {
+ __put_user(child->thread.watch.mips3264.watchlo[i],
+ &addr->WATCH_STYLE.watchlo[i]);
+ __put_user(child->thread.watch.mips3264.watchhi[i] & 0xfff,
+ &addr->WATCH_STYLE.watchhi[i]);
+ }
+
+ return 0;
+}
+
+int ptrace_set_watch_regs(struct task_struct *child,
+ struct pt_watch_regs __user *addr)
+{
+ int i;
+ int watch_active = 0;
+ unsigned long lt[NUM_WATCH_REGS];
+ unsigned int ht[NUM_WATCH_REGS];
+
+ if (!cpu_has_watch || current_cpu_data.watch_reg_use_cnt == 0)
+ return -EIO;
+ if (!access_ok(VERIFY_READ, addr, sizeof(struct pt_watch_regs)))
+ return -EIO;
+ /* Check the values. */
+ for (i = 0; i < NUM_WATCH_REGS; i++) {
+ __get_user(lt[i], &addr->WATCH_STYLE.watchlo[i]);
+#ifdef CONFIG_32BIT
+ if (lt[i] & __UA_LIMIT)
+ return -EINVAL;
+#else
+ if (test_tsk_thread_flag(child, TIF_32BIT_ADDR)) {
+ if (lt[i] & 0xffffffff80000000UL)
+ return -EINVAL;
+ } else {
+ if (lt[i] & __UA_LIMIT)
+ return -EINVAL;
+ }
+#endif
+ __get_user(ht[i], &addr->WATCH_STYLE.watchhi[i]);
+ if (ht[i] & ~0xff8)
+ return -EINVAL;
+ }
+ /* Install them. */
+ for (i = 0; i < NUM_WATCH_REGS; i++) {
+ if ((lt[i] & 7) && i < current_cpu_data.watch_reg_use_cnt)
+ watch_active = 1;
+ child->thread.watch.mips3264.watchlo[i] = lt[i];
+ /* Set the G bit. */
+ child->thread.watch.mips3264.watchhi[i] = ht[i] | 0x40000000;
+ }
+
+ if (watch_active)
+ set_tsk_thread_flag(child, TIF_LOAD_WATCH);
+ else
+ clear_tsk_thread_flag(child, TIF_LOAD_WATCH);
+
+ return 0;
+}
+
long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
int ret;
@@ -440,6 +525,16 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
(unsigned long __user *) data);
break;

+ case PTRACE_GET_WATCH_REGS:
+ ret = ptrace_get_watch_regs(child,
+ (struct pt_watch_regs __user *) addr);
+ break;
+
+ case PTRACE_SET_WATCH_REGS:
+ ret = ptrace_set_watch_regs(child,
+ (struct pt_watch_regs __user *) addr);
+ break;
+
default:
ret = ptrace_request(child, request, addr, data);
break;
diff --git a/arch/mips/kernel/ptrace32.c b/arch/mips/kernel/ptrace32.c
index 76818be..3e219de 100644
--- a/arch/mips/kernel/ptrace32.c
+++ b/arch/mips/kernel/ptrace32.c
@@ -42,6 +42,11 @@ int ptrace_setregs(struct task_struct *child, __s64 __user *data);
int ptrace_getfpregs(struct task_struct *child, __u32 __user *data);
int ptrace_setfpregs(struct task_struct *child, __u32 __user *data);

+int ptrace_get_watch_regs(struct task_struct *child,
+ struct pt_watch_regs __user *addr);
+int ptrace_set_watch_regs(struct task_struct *child,
+ struct pt_watch_regs __user *addr);
+
/*
* Tracing a 32-bit process with a 64-bit strace and vice versa will not
* work. I don't know how to fix this.
@@ -410,6 +415,16 @@ asmlinkage int sys32_ptrace(int request, int pid, int addr, int data)
(unsigned long __user *) (unsigned long) data);
break;

+ case PTRACE_GET_WATCH_REGS:
+ ret = ptrace_get_watch_regs(child,
+ (struct pt_watch_regs __user *) (unsigned long) addr);
+ break;
+
+ case PTRACE_SET_WATCH_REGS:
+ ret = ptrace_set_watch_regs(child,
+ (struct pt_watch_regs __user *) (unsigned long) addr);
+ break;
+
default:
ret = ptrace_request(child, request, addr, data);
break;
diff --git a/include/asm-mips/ptrace.h b/include/asm-mips/ptrace.h
index 786f7e3..d8d821d 100644
--- a/include/asm-mips/ptrace.h
+++ b/include/asm-mips/ptrace.h
@@ -71,6 +71,37 @@ struct pt_regs {
#define PTRACE_POKEDATA_3264 0xc3
#define PTRACE_GET_THREAD_AREA_3264 0xc4

+/* Read and write watchpoint registers. */
+enum pt_watch_style {
+ pt_watch_style_mips32,
+ pt_watch_style_mips64
+};
+struct mips32_watch_regs {
+ uint32_t watchlo[8];
+ uint32_t watchhi[8];
+ uint32_t num_valid;
+ uint32_t reg_mask;
+ uint32_t irw_mask;
+};
+struct mips64_watch_regs {
+ uint64_t watchlo[8];
+ uint32_t watchhi[8];
+ uint32_t num_valid;
+ uint32_t reg_mask;
+ uint32_t irw_mask;
+};
+
+struct pt_watch_regs {
+ enum pt_watch_style style;
+ union {
+ struct mips32_watch_regs mips32;
+ struct mips32_watch_regs mips64;
+ };
+};
+
+#define PTRACE_GET_WATCH_REGS 0xd0
+#define PTRACE_SET_WATCH_REGS 0xd1
+
#ifdef __KERNEL__

#include <linux/linkage.h>
--
1.5.5.1


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