On 04/18, Oleg Nesterov wrote:
>
> 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.
This patch is hardly readable. To simplify the review, I attached the
new/modified code below.
Oleg.
static int ptrace_fill_bp_fields(struct perf_event_attr *attr,
int len, int type, bool disabled)
{
int err, bp_len, bp_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;
return modify_user_hw_breakpoint(bp, &attr);
}
static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
unsigned long addr)
{
struct thread_struct *t = &tsk->thread;
struct perf_event *bp = t->ptrace_bps[nr];
int err = 0;
if (!bp) {
/*
* 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.
* -EINVAL may be what we want for in-kernel breakpoints users,
* but -EIO looks better for ptrace, since we refuse a register
* writing for the user. And anyway this is the previous
* behaviour.
*/
bp = ptrace_register_breakpoint(tsk,
X86_BREAKPOINT_LEN_1, X86_BREAKPOINT_WRITE,
addr, true);
if (IS_ERR(bp))
err = PTR_ERR(bp);
else
t->ptrace_bps[nr] = bp;
} else {
struct perf_event_attr attr = bp->attr;
attr.bp_addr = addr;
err = modify_user_hw_breakpoint(bp, &attr);
}
return err;
}
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