Modify the ptrace code to use the hardware breakpoint interfaces for
user-space
Signed-off-by: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxxxxxxx>
---
arch/s390/include/asm/ptrace.h | 3 -
arch/s390/kernel/process.c | 3 +
arch/s390/kernel/ptrace.c | 221 ++++++++++++++++++++++++++++------------
3 files changed, 158 insertions(+), 69 deletions(-)
diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h
index 95dcf18..28de32f 100644
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -406,7 +406,8 @@ typedef struct
*/
unsigned single_step : 1;
unsigned instruction_fetch : 1;
- unsigned : 30;
+ unsigned storage_alteration: 1;
+ unsigned : 29;
/*
* These addresses are copied into cr10 & cr11 if single
* stepping is switched off
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 00b6d1d..67142d2 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -32,6 +32,7 @@
#include <linux/kernel_stat.h>
#include <linux/syscalls.h>
#include <linux/compat.h>
+#include <linux/hw_breakpoint.h>
#include <asm/compat.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
@@ -153,6 +154,7 @@ void exit_thread(void)
void flush_thread(void)
{
+ flush_ptrace_hw_breakpoint(current);
}
void release_thread(struct task_struct *dead_task)
@@ -215,6 +217,7 @@ int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
p->thread.mm_segment = get_fs();
/* Don't copy debug registers */
memset(&p->thread.per_info, 0, sizeof(p->thread.per_info));
+ memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
/* Initialize per thread user and system timer values */
ti = task_thread_info(p);
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 7cf4642..5bc10da 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -36,6 +36,8 @@
#include <linux/regset.h>
#include <linux/tracehook.h>
#include <linux/seccomp.h>
+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>
#include <trace/syscall.h>
#include <asm/compat.h>
#include <asm/segment.h>
@@ -45,6 +47,7 @@
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
+#include <asm/hw_breakpoint.h>
#include "entry.h"
#ifdef CONFIG_COMPAT
@@ -54,70 +57,100 @@
#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>
+#define PER_INST_FETCH 0x40000000
+#define PER_STG_ALT 0x20000000
+
enum s390_regset {
REGSET_GENERAL,
REGSET_FP,
REGSET_GENERAL_EXTENDED,
};
-static void
-FixPerRegisters(struct task_struct *task)
+static inline unsigned long get_per_addr(per_struct *per_info)
{
- struct pt_regs *regs;
- per_struct *per_info;
- per_cr_words cr_words;
+ if (per_info->single_step)
+ return 0;
- regs = task_pt_regs(task);
- per_info = (per_struct *) &task->thread.per_info;
- per_info->control_regs.bits.em_instruction_fetch =
- per_info->single_step | per_info->instruction_fetch;
-
+ return per_info->starting_addr;
+}
+
+static unsigned long get_per_len(per_struct *per_info)
+{
if (per_info->single_step) {
- per_info->control_regs.bits.starting_addr = 0;
#ifdef CONFIG_COMPAT
if (is_compat_task())
- per_info->control_regs.bits.ending_addr = 0x7fffffffUL;
+ return 0x7fffffffUL;
else
#endif
- per_info->control_regs.bits.ending_addr = PSW_ADDR_INSN;
- } else {
- per_info->control_regs.bits.starting_addr =
- per_info->starting_addr;
- per_info->control_regs.bits.ending_addr =
- per_info->ending_addr;
+ return PSW_ADDR_INSN;
+ } else
+ return per_info->ending_addr - per_info->starting_addr + 1;
+}
+
+static void ptrace_remove_breakpoint(struct task_struct *task)
+{
+ struct perf_event *bp;
+ struct thread_struct *t = &task->thread;
+
+ bp = t->ptrace_bps[0];
+ if (bp) {
+ unregister_hw_breakpoint(bp);
+ t->ptrace_bps[0] = NULL;
}
- /*
- * if any of the control reg tracing bits are on
- * we switch on per in the psw
- */
- if (per_info->control_regs.words.cr[0] & PER_EM_MASK)
- regs->psw.mask |= PSW_MASK_PER;
- else
- regs->psw.mask &= ~PSW_MASK_PER;
-
- if (per_info->control_regs.bits.em_storage_alteration)
- per_info->control_regs.bits.storage_alt_space_ctl = 1;
- else
- per_info->control_regs.bits.storage_alt_space_ctl = 0;
-
- if (task == current) {
- __ctl_store(cr_words, 9, 11);
- if (memcmp(&cr_words, &per_info->control_regs.words,
- sizeof(cr_words)) != 0)
- __ctl_load(per_info->control_regs.words, 9, 11);
+}
+
+static void ptrace_triggered(struct perf_event *bp, int nmi,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ struct thread_struct *thread = &(current->thread);
+
+ thread->ptrace_bps[0] = bp;
+}
+
+static void ptrace_set_breakpoint(struct task_struct *task, int disabled)
+{
+ per_struct *per_info;
+ struct perf_event *bp;
+ struct thread_struct *t = &task->thread;
+ struct perf_event_attr attr;
+
+ hw_breakpoint_init(&attr);
+ per_info = (per_struct *) &task->thread.per_info;
+
+ if (per_info->single_step | per_info->instruction_fetch)
+ attr.bp_type = HW_BREAKPOINT_X;
+ else if (per_info->storage_alteration)
+ attr.bp_type = HW_BREAKPOINT_W;
+ else {
+ ptrace_remove_breakpoint(task);
+ return;
+ }
+
+ attr.disabled = disabled;
+ attr.bp_addr = get_per_addr(per_info);
+ attr.bp_len = get_per_len(per_info);
+
+ if (!t->ptrace_bps[0]) {
+ bp = register_user_hw_breakpoint(&attr, ptrace_triggered, task);
+ if (!IS_ERR(bp))
+ t->ptrace_bps[0] = bp;
+ } else {
+ bp = t->ptrace_bps[0];
+ modify_user_hw_breakpoint(bp, &attr);
}
}
void user_enable_single_step(struct task_struct *task)
{
task->thread.per_info.single_step = 1;
- FixPerRegisters(task);
+ ptrace_set_breakpoint(task, 0);
}
void user_disable_single_step(struct task_struct *task)
{
task->thread.per_info.single_step = 0;
- FixPerRegisters(task);
+ ptrace_set_breakpoint(task, 0);
}
/*
@@ -132,6 +165,40 @@ ptrace_disable(struct task_struct *child)
user_disable_single_step(child);
}
+static inline addr_t get_psw_mask(struct perf_event *bp)
+{
+ return bp->hw.info.type == HW_BREAKPOINT_X ? PER_INST_FETCH :
+ (bp->hw.info.type == HW_BREAKPOINT_W ? PER_STG_ALT : 0);
+}
+
+static addr_t ptrace_get_per_info(struct task_struct *child, addr_t offset)
+{
+ per_struct *dummy = NULL;
+ addr_t tmp;
+ struct thread_struct *thread = &(child->thread);
+
+ if (offset < (addr_t) (&dummy->control_regs + 1)) {
+ struct perf_event *bp = thread->ptrace_bps[0];
+
+ if (!bp)
+ return 0;
+ else if (offset == 0)
+ tmp = get_psw_mask(bp);
+ else if (offset ==
+ (addr_t) (&dummy->control_regs.bits.starting_addr))
+ tmp = bp->hw.info.address;
+ else
+ tmp = bp->hw.info.address + bp->hw.info.len - 1;
+ } else if (offset < (addr_t) &dummy->starting_addr) {
+ tmp = *(addr_t *)((addr_t) &child->thread.per_info + offset);
+ /* reset the storage alteration bit */
+ tmp &= ~PER_STG_ALT;
+ } else
+ tmp = *(addr_t *)((addr_t) &child->thread.per_info + offset);
+
+ return tmp;
+}
+
#ifndef CONFIG_64BIT
# define __ADDR_MASK 3
#else
@@ -202,11 +269,8 @@ static unsigned long __peek_user(struct task_struct *child, addr_t addr)
<< (BITS_PER_LONG - 32);
} else if (addr < (addr_t) (&dummy->regs.per_info + 1)) {
- /*
- * per_info is found in the thread structure
- */
offset = addr - (addr_t) &dummy->regs.per_info;
- tmp = *(addr_t *)((addr_t) &child->thread.per_info + offset);
+ tmp = ptrace_get_per_info(child, offset);
} else
tmp = 0;
@@ -237,6 +301,47 @@ peek_user(struct task_struct *child, addr_t addr, addr_t data)
}
/*
+ * Use hardware breakpoint interface for PER info.
+ */
+static void ptrace_set_per_info(struct task_struct *child, addr_t offset,
+ addr_t data)
+{
+ per_struct *dummy = NULL;
+ int disabled = 0;
+
+ /*
+ * gdb tries to set the PER storage alteration bit in
+ * perf_info->control_regs. With hardware breakpoint interface
+ * in place, we do not want anything to be set in
+ * perf_info->control_regs. Instead we will store this info
+ * in per_info->storage_alteration. Hence make sure that any
+ * further writes from gdb does not wipe out
+ * per_info->storage_alteration info.
+ */
+
+ if (offset == (addr_t) &dummy->control_regs) {
+ if (data & PER_STG_ALT)
+ child->thread.per_info.storage_alteration = 1;
+ else
+ child->thread.per_info.storage_alteration = 0;
+ } else if (offset == (addr_t) (&dummy->control_regs + 1)) {
+ if (child->thread.per_info.storage_alteration) {
+ *(addr_t *)((addr_t) &child->thread.per_info + offset)
+ = data;
+ child->thread.per_info.storage_alteration = 1;
+ } else
+ *(addr_t *)((addr_t) &child->thread.per_info + offset)
+ = data;
+ } else if (offset > (addr_t) (&dummy->control_regs + 1))
+ *(addr_t *)((addr_t) &child->thread.per_info + offset) = data;
+
+ if (offset == (addr_t) &dummy->starting_addr)
+ disabled = 1;
+
+ ptrace_set_breakpoint(child, disabled);
+}
+
+/*
* Write a word to the user area of a process at location addr. This
* operation does have an additional problem compared to peek_user.
* Stores to the program status word and on the floating point
@@ -313,11 +418,9 @@ static int __poke_user(struct task_struct *child, addr_t addr, addr_t data)
* per_info is found in the thread structure
*/
offset = addr - (addr_t) &dummy->regs.per_info;
- *(addr_t *)((addr_t) &child->thread.per_info + offset) = data;
-
+ ptrace_set_per_info(child, offset, data);
}
- FixPerRegisters(child);
return 0;
}
@@ -409,7 +512,6 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
static u32 __peek_user_compat(struct task_struct *child, addr_t addr)
{
struct user32 *dummy32 = NULL;
- per_struct32 *dummy_per32 = NULL;
addr_t offset;
__u32 tmp;
@@ -463,15 +565,8 @@ static u32 __peek_user_compat(struct task_struct *child, addr_t addr)
*/
offset = addr - (addr_t) &dummy32->regs.per_info;
/* This is magic. See per_struct and per_struct32. */
- if ((offset >= (addr_t) &dummy_per32->control_regs &&
- offset < (addr_t) (&dummy_per32->control_regs + 1)) ||
- (offset >= (addr_t) &dummy_per32->starting_addr &&
- offset <= (addr_t) &dummy_per32->ending_addr) ||
- offset == (addr_t) &dummy_per32->lowcore.words.address)
- offset = offset*2 + 4;
- else
- offset = offset*2;
- tmp = *(__u32 *)((addr_t) &child->thread.per_info + offset);
+ offset = offset*2;
+ tmp = (__u32) ptrace_get_per_info(child, offset);
} else
tmp = 0;
@@ -498,7 +593,6 @@ static int __poke_user_compat(struct task_struct *child,
addr_t addr, addr_t data)
{
struct user32 *dummy32 = NULL;
- per_struct32 *dummy_per32 = NULL;
__u32 tmp = (__u32) data;
addr_t offset;
@@ -566,19 +660,10 @@ static int __poke_user_compat(struct task_struct *child,
* because the second half (bytes 4-7) is needed and
* not the first half.
*/
- if ((offset >= (addr_t) &dummy_per32->control_regs &&
- offset < (addr_t) (&dummy_per32->control_regs + 1)) ||
- (offset >= (addr_t) &dummy_per32->starting_addr &&
- offset <= (addr_t) &dummy_per32->ending_addr) ||
- offset == (addr_t) &dummy_per32->lowcore.words.address)
- offset = offset*2 + 4;
- else
- offset = offset*2;
- *(__u32 *)((addr_t) &child->thread.per_info + offset) = tmp;
-
+ offset = offset*2;
+ ptrace_set_per_info(child, offset, data);
}
- FixPerRegisters(child);
return 0;
}
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