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Date: Tue, 17 Mar 2020 11:37:46 +0100
From: Christophe Leroy <christophe.leroy@....fr>
To: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>, mpe@...erman.id.au,
mikey@...ling.org
Cc: apopple@...ux.ibm.com, paulus@...ba.org, npiggin@...il.com,
naveen.n.rao@...ux.vnet.ibm.com, peterz@...radead.org,
jolsa@...nel.org, oleg@...hat.com, fweisbec@...il.com,
mingo@...nel.org, linuxppc-dev@...ts.ozlabs.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 09/15] powerpc/watchpoint: Convert thread_struct->hw_brk
to an array
Le 09/03/2020 à 09:58, Ravi Bangoria a écrit :
> So far powerpc hw supported only one watchpoint. But Future Power
> architecture is introducing 2nd DAWR. Convert thread_struct->hw_brk
> into an array.
Looks like you are doing a lot more than that in this patch.
Should this patch be splitted in two parts ?
Christophe
>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
> ---
> arch/powerpc/include/asm/processor.h | 2 +-
> arch/powerpc/kernel/process.c | 43 ++++++++++++++++++++--------
> arch/powerpc/kernel/ptrace.c | 42 ++++++++++++++++++++-------
> arch/powerpc/kernel/ptrace32.c | 4 +--
> arch/powerpc/kernel/signal.c | 9 ++++--
> 5 files changed, 72 insertions(+), 28 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
> index 666b2825278c..57a8fac2e72b 100644
> --- a/arch/powerpc/include/asm/processor.h
> +++ b/arch/powerpc/include/asm/processor.h
> @@ -183,7 +183,7 @@ struct thread_struct {
> */
> struct perf_event *last_hit_ubp;
> #endif /* CONFIG_HAVE_HW_BREAKPOINT */
> - struct arch_hw_breakpoint hw_brk; /* info on the hardware breakpoint */
> + struct arch_hw_breakpoint hw_brk[HBP_NUM_MAX]; /* hardware breakpoint info */
> unsigned long trap_nr; /* last trap # on this thread */
> u8 load_slb; /* Ages out SLB preload cache entries */
> u8 load_fp;
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index f6bb2586fa5d..42ff62ef749c 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -704,21 +704,25 @@ void switch_booke_debug_regs(struct debug_reg *new_debug)
> EXPORT_SYMBOL_GPL(switch_booke_debug_regs);
> #else /* !CONFIG_PPC_ADV_DEBUG_REGS */
> #ifndef CONFIG_HAVE_HW_BREAKPOINT
> -static void set_breakpoint(struct arch_hw_breakpoint *brk)
> +static void set_breakpoint(struct arch_hw_breakpoint *brk, int i)
> {
> preempt_disable();
> - __set_breakpoint(brk, 0);
> + __set_breakpoint(brk, i);
> preempt_enable();
> }
>
> static void set_debug_reg_defaults(struct thread_struct *thread)
> {
> - thread->hw_brk.address = 0;
> - thread->hw_brk.type = 0;
> - thread->hw_brk.len = 0;
> - thread->hw_brk.hw_len = 0;
> - if (ppc_breakpoint_available())
> - set_breakpoint(&thread->hw_brk);
> + int i;
> +
> + for (i = 0; i < nr_wp_slots(); i++) {
> + thread->hw_brk[i].address = 0;
> + thread->hw_brk[i].type = 0;
> + thread->hw_brk[i].len = 0;
> + thread->hw_brk[i].hw_len = 0;
> + if (ppc_breakpoint_available())
> + set_breakpoint(&thread->hw_brk[i], i);
> + }
> }
> #endif /* !CONFIG_HAVE_HW_BREAKPOINT */
> #endif /* CONFIG_PPC_ADV_DEBUG_REGS */
> @@ -1141,6 +1145,24 @@ static inline void restore_sprs(struct thread_struct *old_thread,
> thread_pkey_regs_restore(new_thread, old_thread);
> }
>
> +#ifndef CONFIG_HAVE_HW_BREAKPOINT
> +static void switch_hw_breakpoint(struct task_struct *new)
> +{
> + int i;
> +
> + for (i = 0; i < nr_wp_slots(); i++) {
> + if (unlikely(!hw_brk_match(this_cpu_ptr(¤t_brk[i]),
> + &new->thread.hw_brk[i]))) {
> + __set_breakpoint(&new->thread.hw_brk[i], i);
> + }
> + }
> +}
> +#else
> +static void switch_hw_breakpoint(struct task_struct *new)
> +{
> +}
> +#endif
> +
> struct task_struct *__switch_to(struct task_struct *prev,
> struct task_struct *new)
> {
> @@ -1172,10 +1194,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
> * For PPC_BOOK3S_64, we use the hw-breakpoint interfaces that would
> * schedule DABR
> */
> -#ifndef CONFIG_HAVE_HW_BREAKPOINT
> - if (unlikely(!hw_brk_match(this_cpu_ptr(¤t_brk[0]), &new->thread.hw_brk)))
> - __set_breakpoint(&new->thread.hw_brk, 0);
> -#endif /* CONFIG_HAVE_HW_BREAKPOINT */
> + switch_hw_breakpoint(new);
> #endif
>
> /*
> diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
> index dd46e174dbe7..f6d7955fc61e 100644
> --- a/arch/powerpc/kernel/ptrace.c
> +++ b/arch/powerpc/kernel/ptrace.c
> @@ -2382,6 +2382,11 @@ void ptrace_triggered(struct perf_event *bp,
> }
> #endif /* CONFIG_HAVE_HW_BREAKPOINT */
>
> +/*
> + * ptrace_set_debugreg() fakes DABR and DABR is only one. So even if
> + * internal hw supports more than one watchpoint, we support only one
> + * watchpoint with this interface.
> + */
> static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
> unsigned long data)
> {
> @@ -2451,7 +2456,7 @@ static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
> return ret;
> }
> thread->ptrace_bps[0] = bp;
> - thread->hw_brk = hw_brk;
> + thread->hw_brk[0] = hw_brk;
> return 0;
> }
>
> @@ -2473,7 +2478,7 @@ static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
> if (set_bp && (!ppc_breakpoint_available()))
> return -ENODEV;
> #endif /* CONFIG_HAVE_HW_BREAKPOINT */
> - task->thread.hw_brk = hw_brk;
> + task->thread.hw_brk[0] = hw_brk;
> #else /* CONFIG_PPC_ADV_DEBUG_REGS */
> /* As described above, it was assumed 3 bits were passed with the data
> * address, but we will assume only the mode bits will be passed
> @@ -2824,9 +2829,23 @@ static int set_dac_range(struct task_struct *child,
> }
> #endif /* CONFIG_PPC_ADV_DEBUG_DAC_RANGE */
>
> +#ifndef CONFIG_PPC_ADV_DEBUG_REGS
> +static int empty_hw_brk(struct thread_struct *thread)
> +{
> + int i;
> +
> + for (i = 0; i < nr_wp_slots(); i++) {
> + if (!thread->hw_brk[i].address)
> + return i;
> + }
> + return -1;
> +}
> +#endif
> +
> static long ppc_set_hwdebug(struct task_struct *child,
> struct ppc_hw_breakpoint *bp_info)
> {
> + int i;
> #ifdef CONFIG_HAVE_HW_BREAKPOINT
> int len = 0;
> struct thread_struct *thread = &(child->thread);
> @@ -2919,15 +2938,16 @@ static long ppc_set_hwdebug(struct task_struct *child,
> if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT)
> return -EINVAL;
>
> - if (child->thread.hw_brk.address)
> + i = empty_hw_brk(&child->thread);
> + if (i < 0)
> return -ENOSPC;
>
> if (!ppc_breakpoint_available())
> return -ENODEV;
>
> - child->thread.hw_brk = brk;
> + child->thread.hw_brk[i] = brk;
>
> - return 1;
> + return i + 1;
> #endif /* !CONFIG_PPC_ADV_DEBUG_DVCS */
> }
>
> @@ -2955,7 +2975,7 @@ static long ppc_del_hwdebug(struct task_struct *child, long data)
> }
> return rc;
> #else
> - if (data != 1)
> + if (data < 1 || data > nr_wp_slots())
> return -EINVAL;
>
> #ifdef CONFIG_HAVE_HW_BREAKPOINT
> @@ -2967,11 +2987,11 @@ static long ppc_del_hwdebug(struct task_struct *child, long data)
> ret = -ENOENT;
> return ret;
> #else /* CONFIG_HAVE_HW_BREAKPOINT */
> - if (child->thread.hw_brk.address == 0)
> + if (child->thread.hw_brk[data - 1].address == 0)
> return -ENOENT;
>
> - child->thread.hw_brk.address = 0;
> - child->thread.hw_brk.type = 0;
> + child->thread.hw_brk[data - 1].address = 0;
> + child->thread.hw_brk[data - 1].type = 0;
> #endif /* CONFIG_HAVE_HW_BREAKPOINT */
>
> return 0;
> @@ -3124,8 +3144,8 @@ long arch_ptrace(struct task_struct *child, long request,
> #ifdef CONFIG_PPC_ADV_DEBUG_REGS
> ret = put_user(child->thread.debug.dac1, datalp);
> #else
> - dabr_fake = ((child->thread.hw_brk.address & (~HW_BRK_TYPE_DABR)) |
> - (child->thread.hw_brk.type & HW_BRK_TYPE_DABR));
> + dabr_fake = ((child->thread.hw_brk[0].address & (~HW_BRK_TYPE_DABR)) |
> + (child->thread.hw_brk[0].type & HW_BRK_TYPE_DABR));
> ret = put_user(dabr_fake, datalp);
> #endif
> break;
> diff --git a/arch/powerpc/kernel/ptrace32.c b/arch/powerpc/kernel/ptrace32.c
> index f37eb53de1a1..e227cd320b46 100644
> --- a/arch/powerpc/kernel/ptrace32.c
> +++ b/arch/powerpc/kernel/ptrace32.c
> @@ -270,8 +270,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
> ret = put_user(child->thread.debug.dac1, (u32 __user *)data);
> #else
> dabr_fake = (
> - (child->thread.hw_brk.address & (~HW_BRK_TYPE_DABR)) |
> - (child->thread.hw_brk.type & HW_BRK_TYPE_DABR));
> + (child->thread.hw_brk[0].address & (~HW_BRK_TYPE_DABR)) |
> + (child->thread.hw_brk[0].type & HW_BRK_TYPE_DABR));
> ret = put_user(dabr_fake, (u32 __user *)data);
> #endif
> break;
> diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
> index 8bc6cc55420a..3116896e89a6 100644
> --- a/arch/powerpc/kernel/signal.c
> +++ b/arch/powerpc/kernel/signal.c
> @@ -107,6 +107,9 @@ static void do_signal(struct task_struct *tsk)
> struct ksignal ksig = { .sig = 0 };
> int ret;
> int is32 = is_32bit_task();
> +#ifndef CONFIG_PPC_ADV_DEBUG_REGS
> + int i;
> +#endif
>
> BUG_ON(tsk != current);
>
> @@ -128,8 +131,10 @@ static void do_signal(struct task_struct *tsk)
> * user space. The DABR will have been cleared if it
> * triggered inside the kernel.
> */
> - if (tsk->thread.hw_brk.address && tsk->thread.hw_brk.type)
> - __set_breakpoint(&tsk->thread.hw_brk, 0);
> + for (i = 0; i < nr_wp_slots(); i++) {
> + if (tsk->thread.hw_brk[i].address && tsk->thread.hw_brk[i].type)
> + __set_breakpoint(&tsk->thread.hw_brk[i], i);
> + }
> #endif
> /* Re-enable the breakpoints for the signal stack */
> thread_change_pc(tsk, tsk->thread.regs);
>
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