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Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/l…
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…inux/kernel/git/tip/linux-2.6-tip

* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  perf, hw_breakpoint, kgdb: Do not take mutex for kernel debugger
  x86, hw_breakpoints, kgdb: Fix kgdb to use hw_breakpoint API
  hw_breakpoints: Release the bp slot if arch_validate_hwbkpt_settings() fails.
  perf: Ignore perf.data.old
  perf report: Fix segmentation fault when running with '-g none'
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Linus Torvalds committed Feb 1, 2010
2 parents 8ea85c2 + 5352ae6 commit 834db33
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Showing 6 changed files with 218 additions and 68 deletions.
222 changes: 165 additions & 57 deletions arch/x86/kernel/kgdb.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/nmi.h>
#include <linux/hw_breakpoint.h>

#include <asm/debugreg.h>
#include <asm/apicdef.h>
Expand Down Expand Up @@ -204,40 +205,81 @@ void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)

static struct hw_breakpoint {
unsigned enabled;
unsigned type;
unsigned len;
unsigned long addr;
int len;
int type;
struct perf_event **pev;
} breakinfo[4];

static void kgdb_correct_hw_break(void)
{
unsigned long dr7;
int correctit = 0;
int breakbit;
int breakno;

get_debugreg(dr7, 7);
for (breakno = 0; breakno < 4; breakno++) {
breakbit = 2 << (breakno << 1);
if (!(dr7 & breakbit) && breakinfo[breakno].enabled) {
correctit = 1;
dr7 |= breakbit;
dr7 &= ~(0xf0000 << (breakno << 2));
dr7 |= ((breakinfo[breakno].len << 2) |
breakinfo[breakno].type) <<
((breakno << 2) + 16);
set_debugreg(breakinfo[breakno].addr, breakno);

} else {
if ((dr7 & breakbit) && !breakinfo[breakno].enabled) {
correctit = 1;
dr7 &= ~breakbit;
dr7 &= ~(0xf0000 << (breakno << 2));
}
}
struct perf_event *bp;
struct arch_hw_breakpoint *info;
int val;
int cpu = raw_smp_processor_id();
if (!breakinfo[breakno].enabled)
continue;
bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu);
info = counter_arch_bp(bp);
if (bp->attr.disabled != 1)
continue;
bp->attr.bp_addr = breakinfo[breakno].addr;
bp->attr.bp_len = breakinfo[breakno].len;
bp->attr.bp_type = breakinfo[breakno].type;
info->address = breakinfo[breakno].addr;
info->len = breakinfo[breakno].len;
info->type = breakinfo[breakno].type;
val = arch_install_hw_breakpoint(bp);
if (!val)
bp->attr.disabled = 0;
}
hw_breakpoint_restore();
}

static int hw_break_reserve_slot(int breakno)
{
int cpu;
int cnt = 0;
struct perf_event **pevent;

for_each_online_cpu(cpu) {
cnt++;
pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
if (dbg_reserve_bp_slot(*pevent))
goto fail;
}

return 0;

fail:
for_each_online_cpu(cpu) {
cnt--;
if (!cnt)
break;
pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
dbg_release_bp_slot(*pevent);
}
if (correctit)
set_debugreg(dr7, 7);
return -1;
}

static int hw_break_release_slot(int breakno)
{
struct perf_event **pevent;
int cpu;

for_each_online_cpu(cpu) {
pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
if (dbg_release_bp_slot(*pevent))
/*
* The debugger is responisble for handing the retry on
* remove failure.
*/
return -1;
}
return 0;
}

static int
Expand All @@ -251,6 +293,10 @@ kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
if (i == 4)
return -1;

if (hw_break_release_slot(i)) {
printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr);
return -1;
}
breakinfo[i].enabled = 0;

return 0;
Expand All @@ -259,15 +305,23 @@ kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
static void kgdb_remove_all_hw_break(void)
{
int i;
int cpu = raw_smp_processor_id();
struct perf_event *bp;

for (i = 0; i < 4; i++)
memset(&breakinfo[i], 0, sizeof(struct hw_breakpoint));
for (i = 0; i < 4; i++) {
if (!breakinfo[i].enabled)
continue;
bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
if (bp->attr.disabled == 1)
continue;
arch_uninstall_hw_breakpoint(bp);
bp->attr.disabled = 1;
}
}

static int
kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
{
unsigned type;
int i;

for (i = 0; i < 4; i++)
Expand All @@ -278,27 +332,42 @@ kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)

switch (bptype) {
case BP_HARDWARE_BREAKPOINT:
type = 0;
len = 1;
len = 1;
breakinfo[i].type = X86_BREAKPOINT_EXECUTE;
break;
case BP_WRITE_WATCHPOINT:
type = 1;
breakinfo[i].type = X86_BREAKPOINT_WRITE;
break;
case BP_ACCESS_WATCHPOINT:
type = 3;
breakinfo[i].type = X86_BREAKPOINT_RW;
break;
default:
return -1;
}

if (len == 1 || len == 2 || len == 4)
breakinfo[i].len = len - 1;
else
switch (len) {
case 1:
breakinfo[i].len = X86_BREAKPOINT_LEN_1;
break;
case 2:
breakinfo[i].len = X86_BREAKPOINT_LEN_2;
break;
case 4:
breakinfo[i].len = X86_BREAKPOINT_LEN_4;
break;
#ifdef CONFIG_X86_64
case 8:
breakinfo[i].len = X86_BREAKPOINT_LEN_8;
break;
#endif
default:
return -1;

breakinfo[i].enabled = 1;
}
breakinfo[i].addr = addr;
breakinfo[i].type = type;
if (hw_break_reserve_slot(i)) {
breakinfo[i].addr = 0;
return -1;
}
breakinfo[i].enabled = 1;

return 0;
}
Expand All @@ -313,8 +382,21 @@ kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
*/
void kgdb_disable_hw_debug(struct pt_regs *regs)
{
int i;
int cpu = raw_smp_processor_id();
struct perf_event *bp;

/* Disable hardware debugging while we are in kgdb: */
set_debugreg(0UL, 7);
for (i = 0; i < 4; i++) {
if (!breakinfo[i].enabled)
continue;
bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
if (bp->attr.disabled == 1)
continue;
arch_uninstall_hw_breakpoint(bp);
bp->attr.disabled = 1;
}
}

/**
Expand Down Expand Up @@ -378,7 +460,6 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
struct pt_regs *linux_regs)
{
unsigned long addr;
unsigned long dr6;
char *ptr;
int newPC;

Expand All @@ -404,20 +485,6 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
raw_smp_processor_id());
}

get_debugreg(dr6, 6);
if (!(dr6 & 0x4000)) {
int breakno;

for (breakno = 0; breakno < 4; breakno++) {
if (dr6 & (1 << breakno) &&
breakinfo[breakno].type == 0) {
/* Set restore flag: */
linux_regs->flags |= X86_EFLAGS_RF;
break;
}
}
}
set_debugreg(0UL, 6);
kgdb_correct_hw_break();

return 0;
Expand Down Expand Up @@ -485,8 +552,7 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd)
break;

case DIE_DEBUG:
if (atomic_read(&kgdb_cpu_doing_single_step) ==
raw_smp_processor_id()) {
if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
if (user_mode(regs))
return single_step_cont(regs, args);
break;
Expand Down Expand Up @@ -539,7 +605,42 @@ static struct notifier_block kgdb_notifier = {
*/
int kgdb_arch_init(void)
{
return register_die_notifier(&kgdb_notifier);
int i, cpu;
int ret;
struct perf_event_attr attr;
struct perf_event **pevent;

ret = register_die_notifier(&kgdb_notifier);
if (ret != 0)
return ret;
/*
* Pre-allocate the hw breakpoint structions in the non-atomic
* portion of kgdb because this operation requires mutexs to
* complete.
*/
attr.bp_addr = (unsigned long)kgdb_arch_init;
attr.type = PERF_TYPE_BREAKPOINT;
attr.bp_len = HW_BREAKPOINT_LEN_1;
attr.bp_type = HW_BREAKPOINT_W;
attr.disabled = 1;
for (i = 0; i < 4; i++) {
breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL);
if (IS_ERR(breakinfo[i].pev)) {
printk(KERN_ERR "kgdb: Could not allocate hw breakpoints\n");
breakinfo[i].pev = NULL;
kgdb_arch_exit();
return -1;
}
for_each_online_cpu(cpu) {
pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
pevent[0]->hw.sample_period = 1;
if (pevent[0]->destroy != NULL) {
pevent[0]->destroy = NULL;
release_bp_slot(*pevent);
}
}
}
return ret;
}

/**
Expand All @@ -550,6 +651,13 @@ int kgdb_arch_init(void)
*/
void kgdb_arch_exit(void)
{
int i;
for (i = 0; i < 4; i++) {
if (breakinfo[i].pev) {
unregister_wide_hw_breakpoint(breakinfo[i].pev);
breakinfo[i].pev = NULL;
}
}
unregister_die_notifier(&kgdb_notifier);
}

Expand Down
2 changes: 2 additions & 0 deletions include/linux/hw_breakpoint.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,8 @@ extern int __register_perf_hw_breakpoint(struct perf_event *bp);
extern void unregister_hw_breakpoint(struct perf_event *bp);
extern void unregister_wide_hw_breakpoint(struct perf_event **cpu_events);

extern int dbg_reserve_bp_slot(struct perf_event *bp);
extern int dbg_release_bp_slot(struct perf_event *bp);
extern int reserve_bp_slot(struct perf_event *bp);
extern void release_bp_slot(struct perf_event *bp);

Expand Down
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