ptrace/x86: introduce ptrace_register_breakpoint()
No functional changes, preparation.
Extract the "register breakpoint" code from ptrace_get_debugreg() into
the new/generic helper, ptrace_register_breakpoint(). It will have more
users.
The patch also adds another simple helper, ptrace_fill_bp_fields(), to
factor out the arch_bp_generic_fields() logic in register/modify.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 98b0a2c..0526368 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -601,23 +601,49 @@
return dr7;
}
-static int
-ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
- struct task_struct *tsk, int disabled)
+static int ptrace_fill_bp_fields(struct perf_event_attr *attr,
+ int len, int type, bool disabled)
{
- int err;
- int gen_len, gen_type;
- struct perf_event_attr attr;
+ int err, bp_len, bp_type;
- err = arch_bp_generic_fields(len, type, &gen_len, &gen_type);
+ err = arch_bp_generic_fields(len, type, &bp_len, &bp_type);
+ if (!err) {
+ attr->bp_len = bp_len;
+ attr->bp_type = bp_type;
+ attr->disabled = disabled;
+ }
+
+ return err;
+}
+
+static struct perf_event *
+ptrace_register_breakpoint(struct task_struct *tsk, int len, int type,
+ unsigned long addr, bool disabled)
+{
+ struct perf_event_attr attr;
+ int err;
+
+ ptrace_breakpoint_init(&attr);
+ attr.bp_addr = addr;
+
+ err = ptrace_fill_bp_fields(&attr, len, type, disabled);
+ if (err)
+ return ERR_PTR(err);
+
+ return register_user_hw_breakpoint(&attr, ptrace_triggered,
+ NULL, tsk);
+}
+
+static int ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
+ int disabled)
+{
+ struct perf_event_attr attr = bp->attr;
+ int err;
+
+ err = ptrace_fill_bp_fields(&attr, len, type, disabled);
if (err)
return err;
- attr = bp->attr;
- attr.bp_len = gen_len;
- attr.bp_type = gen_type;
- attr.disabled = disabled;
-
return modify_user_hw_breakpoint(bp, &attr);
}
@@ -653,7 +679,7 @@
break;
}
- rc = ptrace_modify_breakpoint(bp, len, type, tsk, disabled);
+ rc = ptrace_modify_breakpoint(bp, len, type, disabled);
if (rc)
break;
}
@@ -693,26 +719,14 @@
static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
unsigned long addr)
{
- struct perf_event *bp;
struct thread_struct *t = &tsk->thread;
- struct perf_event_attr attr;
+ struct perf_event *bp = t->ptrace_bps[nr];
int err = 0;
- if (!t->ptrace_bps[nr]) {
- ptrace_breakpoint_init(&attr);
+ if (!bp) {
/*
- * Put stub len and type to register (reserve) an inactive but
- * correct bp
- */
- attr.bp_addr = addr;
- attr.bp_len = HW_BREAKPOINT_LEN_1;
- attr.bp_type = HW_BREAKPOINT_W;
- attr.disabled = 1;
-
- bp = register_user_hw_breakpoint(&attr, ptrace_triggered,
- NULL, tsk);
-
- /*
+ * Put stub len and type to create an inactive but correct bp.
+ *
* CHECKME: the previous code returned -EIO if the addr wasn't
* a valid task virtual addr. The new one will return -EINVAL in
* this case.
@@ -721,20 +735,20 @@
* writing for the user. And anyway this is the previous
* behaviour.
*/
- if (IS_ERR(bp)) {
+ bp = ptrace_register_breakpoint(tsk,
+ X86_BREAKPOINT_LEN_1, X86_BREAKPOINT_WRITE,
+ addr, true);
+ if (IS_ERR(bp))
err = PTR_ERR(bp);
- goto out;
- }
-
- t->ptrace_bps[nr] = bp;
+ else
+ t->ptrace_bps[nr] = bp;
} else {
- bp = t->ptrace_bps[nr];
+ struct perf_event_attr attr = bp->attr;
- attr = bp->attr;
attr.bp_addr = addr;
err = modify_user_hw_breakpoint(bp, &attr);
}
-out:
+
return err;
}