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powerpc/watchpoint: Use loop for thread_struct->ptrace_bps 

ptrace_bps is already an array of size HBP_NUM_MAX. But we use
hardcoded index 0 while fetching/updating it. Convert such code
to loop over array.

ptrace interface to use multiple watchpoint remains same. eg:
two PPC_PTRACE_SETHWDEBUG calls will create two watchpoint if
underneath hw supports it.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-11-ravi.bangoria@linux.ibm.com
This commit is contained in:
Ravi Bangoria 2020-05-14 16:47:35 +05:30 committed by Michael Ellerman
parent 303e6a9ddc
commit 6b424efa11
3 changed files with 31 additions and 10 deletions
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7
arch/powerpc/kernel/hw_breakpoint.c
View File

@ -420,10 +420,13 @@ NOKPROBE_SYMBOL(hw_breakpoint_exceptions_notify);
*/
void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
{
int i;
struct thread_struct *t = &tsk->thread;
unregister_hw_breakpoint(t->ptrace_bps[0]);
t->ptrace_bps[0] = NULL;
for (i = 0; i < nr_wp_slots(); i++) {
unregister_hw_breakpoint(t->ptrace_bps[i]);
t->ptrace_bps[i] = NULL;
}
}
void hw_breakpoint_pmu_read(struct perf_event *bp)

6
arch/powerpc/kernel/process.c
View File

@ -1604,6 +1604,9 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long usp,
void (*f)(void);
unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
struct thread_info *ti = task_thread_info(p);
#ifdef CONFIG_HAVE_HW_BREAKPOINT
int i;
#endif
klp_init_thread_info(p);
@ -1663,7 +1666,8 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long usp,
p->thread.ksp_limit = (unsigned long)end_of_stack(p);
#endif
#ifdef CONFIG_HAVE_HW_BREAKPOINT
p->thread.ptrace_bps[0] = NULL;
for (i = 0; i < nr_wp_slots(); i++)
p->thread.ptrace_bps[i] = NULL;
#endif
p->thread.fp_save_area = NULL;

28
arch/powerpc/kernel/ptrace/ptrace-noadv.c
View File

@ -168,6 +168,19 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, unsigned l
return 0;
}
#ifdef CONFIG_HAVE_HW_BREAKPOINT
static int find_empty_ptrace_bp(struct thread_struct *thread)
{
int i;
for (i = 0; i < nr_wp_slots(); i++) {
if (!thread->ptrace_bps[i])
return i;
}
return -1;
}
#endif
static int find_empty_hw_brk(struct thread_struct *thread)
{
int i;
@ -217,8 +230,9 @@ long ppc_set_hwdebug(struct task_struct *child, struct ppc_hw_breakpoint *bp_inf
len = 1;
else
return -EINVAL;
bp = thread->ptrace_bps[0];
if (bp)
i = find_empty_ptrace_bp(thread);
if (i < 0)
return -ENOSPC;
/* Create a new breakpoint request if one doesn't exist already */
@ -228,13 +242,13 @@ long ppc_set_hwdebug(struct task_struct *child, struct ppc_hw_breakpoint *bp_inf
arch_bp_generic_fields(brk.type, &attr.bp_type);
bp = register_user_hw_breakpoint(&attr, ptrace_triggered, NULL, child);
thread->ptrace_bps[0] = bp;
thread->ptrace_bps[i] = bp;
if (IS_ERR(bp)) {
thread->ptrace_bps[0] = NULL;
thread->ptrace_bps[i] = NULL;
return PTR_ERR(bp);
}
return 1;
return i + 1;
#endif /* CONFIG_HAVE_HW_BREAKPOINT */
if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT)
@ -263,10 +277,10 @@ long ppc_del_hwdebug(struct task_struct *child, long data)
return -EINVAL;
#ifdef CONFIG_HAVE_HW_BREAKPOINT
bp = thread->ptrace_bps[0];
bp = thread->ptrace_bps[data - 1];
if (bp) {
unregister_hw_breakpoint(bp);
thread->ptrace_bps[0] = NULL;
thread->ptrace_bps[data - 1] = NULL;
} else {
ret = -ENOENT;
}