Messages in this thread | | | Subject | Re: [PATCH 10/15] powerpc/watchpoint: Use loop for thread_struct->ptrace_bps | From | Christophe Leroy <> | Date | Tue, 17 Mar 2020 11:48:12 +0100 |
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Le 09/03/2020 à 09:58, Ravi Bangoria a écrit : > 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. > > Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> > --- > arch/powerpc/kernel/hw_breakpoint.c | 7 +++++-- > arch/powerpc/kernel/process.c | 6 +++++- > arch/powerpc/kernel/ptrace.c | 28 +++++++++++++++++++++------- > 3 files changed, 31 insertions(+), 10 deletions(-) > > diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c > index f4d48f87dcb8..b27aca623267 100644 > --- a/arch/powerpc/kernel/hw_breakpoint.c > +++ b/arch/powerpc/kernel/hw_breakpoint.c > @@ -419,10 +419,13 @@ 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) > diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c > index 42ff62ef749c..b9ab740fcacf 100644 > --- a/arch/powerpc/kernel/process.c > +++ b/arch/powerpc/kernel/process.c > @@ -1628,6 +1628,9 @@ 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
Could we avoid all those #ifdefs ?
I think if we make p->thread.ptrace_bps[] exist all the time, with a size of 0 when CONFIG_HAVE_HW_BREAKPOINT is not set, then we can drop a lot of #ifdefs.
> > klp_init_thread_info(p); > > @@ -1687,7 +1690,8 @@ 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; > diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c > index f6d7955fc61e..e2651f86d56f 100644 > --- a/arch/powerpc/kernel/ptrace.c > +++ b/arch/powerpc/kernel/ptrace.c
You'll have to rebase all this on the series https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=161356 which is about to go into powerpc-next
> @@ -2829,6 +2829,19 @@ static int set_dac_range(struct task_struct *child, > } > #endif /* CONFIG_PPC_ADV_DEBUG_DAC_RANGE */ > > +#ifdef CONFIG_HAVE_HW_BREAKPOINT > +static int 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
What does this function do exactly ? I seems to do more than what its name suggests.
> + > #ifndef CONFIG_PPC_ADV_DEBUG_REGS > static int empty_hw_brk(struct thread_struct *thread) > { > @@ -2915,8 +2928,9 @@ static long ppc_set_hwdebug(struct task_struct *child, > len = 1; > else > return -EINVAL; > - bp = thread->ptrace_bps[0]; > - if (bp) > + > + i = empty_ptrace_bp(thread); > + if (i < 0) > return -ENOSPC; > > /* Create a new breakpoint request if one doesn't exist already */ > @@ -2925,14 +2939,14 @@ static long ppc_set_hwdebug(struct task_struct *child, > attr.bp_len = len; > arch_bp_generic_fields(brk.type, &attr.bp_type); > > - thread->ptrace_bps[0] = bp = register_user_hw_breakpoint(&attr, > + thread->ptrace_bps[i] = bp = register_user_hw_breakpoint(&attr, > ptrace_triggered, NULL, child); > 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) > @@ -2979,10 +2993,10 @@ static 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];
Is data checked somewhere to ensure it is not out of boundaries ? Or are we sure it is always within ?
> if (bp) { > unregister_hw_breakpoint(bp); > - thread->ptrace_bps[0] = NULL; > + thread->ptrace_bps[data - 1] = NULL; > } else > ret = -ENOENT; > return ret; >
Christophe
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