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Diffstat (limited to 'arch/x86/kernel/hw_breakpoint.c')
-rw-r--r--arch/x86/kernel/hw_breakpoint.c183
1 files changed, 77 insertions, 106 deletions
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index 05d5fec64a9..5f9cf20cdb6 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -32,13 +32,11 @@
#include <linux/irqflags.h>
#include <linux/notifier.h>
#include <linux/kallsyms.h>
-#include <linux/kprobes.h>
#include <linux/percpu.h>
#include <linux/kdebug.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
-#include <linux/init.h>
#include <linux/smp.h>
#include <asm/hw_breakpoint.h>
@@ -122,7 +120,7 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
return -EBUSY;
set_debugreg(info->address, i);
- __get_cpu_var(cpu_debugreg[i]) = info->address;
+ __this_cpu_write(cpu_debugreg[i], info->address);
dr7 = &__get_cpu_var(cpu_dr7);
*dr7 |= encode_dr7(i, info->len, info->type);
@@ -189,51 +187,42 @@ static int get_hbp_len(u8 hbp_len)
}
/*
- * Check for virtual address in user space.
- */
-int arch_check_va_in_userspace(unsigned long va, u8 hbp_len)
-{
- unsigned int len;
-
- len = get_hbp_len(hbp_len);
-
- return (va <= TASK_SIZE - len);
-}
-
-/*
* Check for virtual address in kernel space.
*/
-static int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len)
+int arch_check_bp_in_kernelspace(struct perf_event *bp)
{
unsigned int len;
+ unsigned long va;
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
- len = get_hbp_len(hbp_len);
+ va = info->address;
+ len = get_hbp_len(info->len);
return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
}
-/*
- * Store a breakpoint's encoded address, length, and type.
- */
-static int arch_store_info(struct perf_event *bp)
-{
- struct arch_hw_breakpoint *info = counter_arch_bp(bp);
- /*
- * For kernel-addresses, either the address or symbol name can be
- * specified.
- */
- if (info->name)
- info->address = (unsigned long)
- kallsyms_lookup_name(info->name);
- if (info->address)
- return 0;
-
- return -EINVAL;
-}
-
int arch_bp_generic_fields(int x86_len, int x86_type,
int *gen_len, int *gen_type)
{
+ /* Type */
+ switch (x86_type) {
+ case X86_BREAKPOINT_EXECUTE:
+ if (x86_len != X86_BREAKPOINT_LEN_X)
+ return -EINVAL;
+
+ *gen_type = HW_BREAKPOINT_X;
+ *gen_len = sizeof(long);
+ return 0;
+ case X86_BREAKPOINT_WRITE:
+ *gen_type = HW_BREAKPOINT_W;
+ break;
+ case X86_BREAKPOINT_RW:
+ *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
+ break;
+ default:
+ return -EINVAL;
+ }
+
/* Len */
switch (x86_len) {
case X86_BREAKPOINT_LEN_1:
@@ -254,21 +243,6 @@ int arch_bp_generic_fields(int x86_len, int x86_type,
return -EINVAL;
}
- /* Type */
- switch (x86_type) {
- case X86_BREAKPOINT_EXECUTE:
- *gen_type = HW_BREAKPOINT_X;
- break;
- case X86_BREAKPOINT_WRITE:
- *gen_type = HW_BREAKPOINT_W;
- break;
- case X86_BREAKPOINT_RW:
- *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
- break;
- default:
- return -EINVAL;
- }
-
return 0;
}
@@ -279,6 +253,29 @@ static int arch_build_bp_info(struct perf_event *bp)
info->address = bp->attr.bp_addr;
+ /* Type */
+ switch (bp->attr.bp_type) {
+ case HW_BREAKPOINT_W:
+ info->type = X86_BREAKPOINT_WRITE;
+ break;
+ case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
+ info->type = X86_BREAKPOINT_RW;
+ break;
+ case HW_BREAKPOINT_X:
+ info->type = X86_BREAKPOINT_EXECUTE;
+ /*
+ * x86 inst breakpoints need to have a specific undefined len.
+ * But we still need to check userspace is not trying to setup
+ * an unsupported length, to get a range breakpoint for example.
+ */
+ if (bp->attr.bp_len == sizeof(long)) {
+ info->len = X86_BREAKPOINT_LEN_X;
+ return 0;
+ }
+ default:
+ return -EINVAL;
+ }
+
/* Len */
switch (bp->attr.bp_len) {
case HW_BREAKPOINT_LEN_1:
@@ -299,28 +296,12 @@ static int arch_build_bp_info(struct perf_event *bp)
return -EINVAL;
}
- /* Type */
- switch (bp->attr.bp_type) {
- case HW_BREAKPOINT_W:
- info->type = X86_BREAKPOINT_WRITE;
- break;
- case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
- info->type = X86_BREAKPOINT_RW;
- break;
- case HW_BREAKPOINT_X:
- info->type = X86_BREAKPOINT_EXECUTE;
- break;
- default:
- return -EINVAL;
- }
-
return 0;
}
/*
* Validate the arch-specific HW Breakpoint register settings
*/
-int arch_validate_hwbkpt_settings(struct perf_event *bp,
- struct task_struct *tsk)
+int arch_validate_hwbkpt_settings(struct perf_event *bp)
{
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
unsigned int align;
@@ -333,16 +314,6 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp,
ret = -EINVAL;
- if (info->type == X86_BREAKPOINT_EXECUTE)
- /*
- * Ptrace-refactoring code
- * For now, we'll allow instruction breakpoint only for user-space
- * addresses
- */
- if ((!arch_check_va_in_userspace(info->address, info->len)) &&
- info->len != X86_BREAKPOINT_EXECUTE)
- return ret;
-
switch (info->len) {
case X86_BREAKPOINT_LEN_1:
align = 0;
@@ -362,10 +333,6 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp,
return ret;
}
- ret = arch_store_info(bp);
-
- if (ret < 0)
- return ret;
/*
* Check that the low-order bits of the address are appropriate
* for the alignment implied by len.
@@ -373,15 +340,6 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp,
if (info->address & align)
return -EINVAL;
- /* Check that the virtual address is in the proper range */
- if (tsk) {
- if (!arch_check_va_in_userspace(info->address, info->len))
- return -EFAULT;
- } else {
- if (!arch_check_va_in_kernelspace(info->address, info->len))
- return -EFAULT;
- }
-
return 0;
}
@@ -433,16 +391,19 @@ void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
unregister_hw_breakpoint(t->ptrace_bps[i]);
t->ptrace_bps[i] = NULL;
}
+
+ t->debugreg6 = 0;
+ t->ptrace_dr7 = 0;
}
void hw_breakpoint_restore(void)
{
- set_debugreg(__get_cpu_var(cpu_debugreg[0]), 0);
- set_debugreg(__get_cpu_var(cpu_debugreg[1]), 1);
- set_debugreg(__get_cpu_var(cpu_debugreg[2]), 2);
- set_debugreg(__get_cpu_var(cpu_debugreg[3]), 3);
+ set_debugreg(__this_cpu_read(cpu_debugreg[0]), 0);
+ set_debugreg(__this_cpu_read(cpu_debugreg[1]), 1);
+ set_debugreg(__this_cpu_read(cpu_debugreg[2]), 2);
+ set_debugreg(__this_cpu_read(cpu_debugreg[3]), 3);
set_debugreg(current->thread.debugreg6, 6);
- set_debugreg(__get_cpu_var(cpu_dr7), 7);
+ set_debugreg(__this_cpu_read(cpu_dr7), 7);
}
EXPORT_SYMBOL_GPL(hw_breakpoint_restore);
@@ -462,7 +423,7 @@ EXPORT_SYMBOL_GPL(hw_breakpoint_restore);
* NOTIFY_STOP returned for all other cases
*
*/
-static int __kprobes hw_breakpoint_handler(struct die_args *args)
+static int hw_breakpoint_handler(struct die_args *args)
{
int i, cpu, rc = NOTIFY_STOP;
struct perf_event *bp;
@@ -473,6 +434,10 @@ static int __kprobes hw_breakpoint_handler(struct die_args *args)
dr6_p = (unsigned long *)ERR_PTR(args->err);
dr6 = *dr6_p;
+ /* If it's a single step, TRAP bits are random */
+ if (dr6 & DR_STEP)
+ return NOTIFY_DONE;
+
/* Do an early return if no trap bits are set in DR6 */
if ((dr6 & DR_TRAP_BITS) == 0)
return NOTIFY_DONE;
@@ -502,8 +467,6 @@ static int __kprobes hw_breakpoint_handler(struct die_args *args)
rcu_read_lock();
bp = per_cpu(bp_per_reg[i], cpu);
- if (bp)
- rc = NOTIFY_DONE;
/*
* Reset the 'i'th TRAP bit in dr6 to denote completion of
* exception handling
@@ -520,9 +483,22 @@ static int __kprobes hw_breakpoint_handler(struct die_args *args)
perf_bp_event(bp, args->regs);
+ /*
+ * Set up resume flag to avoid breakpoint recursion when
+ * returning back to origin.
+ */
+ if (bp->hw.info.type == X86_BREAKPOINT_EXECUTE)
+ args->regs->flags |= X86_EFLAGS_RF;
+
rcu_read_unlock();
}
- if (dr6 & (~DR_TRAP_BITS))
+ /*
+ * Further processing in do_debug() is needed for a) user-space
+ * breakpoints (to generate signals) and b) when the system has
+ * taken exception due to multiple causes
+ */
+ if ((current->thread.debugreg6 & DR_TRAP_BITS) ||
+ (dr6 & (~DR_TRAP_BITS)))
rc = NOTIFY_DONE;
set_debugreg(dr7, 7);
@@ -534,7 +510,7 @@ static int __kprobes hw_breakpoint_handler(struct die_args *args)
/*
* Handle debug exception notifications.
*/
-int __kprobes hw_breakpoint_exceptions_notify(
+int hw_breakpoint_exceptions_notify(
struct notifier_block *unused, unsigned long val, void *data)
{
if (val != DIE_DEBUG)
@@ -547,8 +523,3 @@ void hw_breakpoint_pmu_read(struct perf_event *bp)
{
/* TODO */
}
-
-void hw_breakpoint_pmu_unthrottle(struct perf_event *bp)
-{
- /* TODO */
-}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-11-09 18:23:09 +0000