lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <4e5ebad50810301911mb4eed2du398826e79b0f2e28@mail.gmail.com>
Date:	Fri, 31 Oct 2008 10:11:11 +0800
From:	"Sonic Zhang" <sonic.adi@...il.com>
To:	"Jason Wessel" <jason.wessel@...driver.com>
Cc:	"Linux Kernel" <linux-kernel@...r.kernel.org>,
	"kgdb mailing list" <kgdb-bugreport@...ts.sourceforge.net>
Subject: Re: [PATCH] [kgdb] Switch master cpu after gdb thread command for SMP (v3)

Hi Jason,

Does this patch applied on your developing tree well? Any comments?

Thanks

Sonic

On Wed, Oct 22, 2008 at 4:40 PM, sonic zhang <sonic.adi@...il.com> wrote:
>   In blackfin SMP architecture, different core has its own L1 SRAM and MMR
>   memory, which code running on the other core can't access. In current kgdb
>   impelemntation, cpus are represented by thread with minus prefix.
>
> If user run thread command in gdb to switch to the thread of the other cpu,
> kgdb should:
> 1. send IPI signal to master cpu
> 2. release the specific passive cpu waiting in IPI handler
> 3. exit kgdb exception loop on master cpu and trap into kgdb wait in IPI handler
> 4. trap the released passive cpu into kgdb exception in IPI handler
>
> Signed-off-by: Sonic Zhang <sonic.adi@...il.com>
> ---
>  include/linux/kgdb.h |   16 +++++++++++-
>  kernel/kgdb.c        |   66 +++++++++++++++++++++++++++++++++++++++++++-------
>  2 files changed, 72 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
> index 6adcc29..664e396 100644
> --- a/include/linux/kgdb.h
> +++ b/include/linux/kgdb.h
> @@ -106,7 +106,8 @@ struct kgdb_bkpt {
>  # define KGDB_MAX_BREAKPOINTS  1000
>  #endif
>
> -#define KGDB_HW_BREAKPOINT     1
> +#define KGDB_HW_BREAKPOINT     0x1
> +#define KGDB_THR_PROC_SWAP     0x2
>
>  /*
>  * Functions each KGDB-supporting architecture must provide:
> @@ -203,6 +204,19 @@ kgdb_arch_handle_exception(int vector, int signo, int err_code,
>  */
>  extern void kgdb_roundup_cpus(unsigned long flags);
>
> +/**
> + *     kgdb_roundup_cpu - Get spcific CPU into a holding pattern
> + *     @cpu: Specific cpu id
> + *     @flags: Current IRQ state
> + *
> + *     On SMP systems, we need to switch cpu from current active one to
> + *     the other passive one. This get current active CPU into a known state
> + *     in kgdb_wait().
> + *
> + *     On non-SMP systems, this is not called.
> + */
> +extern void kgdb_roundup_cpu(int cpu, unsigned long flags);
> +
>  /* Optional functions. */
>  extern int kgdb_validate_break_address(unsigned long addr);
>  extern int kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr);
> diff --git a/kernel/kgdb.c b/kernel/kgdb.c
> index e4dcfb2..277986d 100644
> --- a/kernel/kgdb.c
> +++ b/kernel/kgdb.c
> @@ -565,6 +565,7 @@ static void kgdb_wait(struct pt_regs *regs)
>  {
>        unsigned long flags;
>        int cpu;
> +       struct task_struct *thread;
>
>        local_irq_save(flags);
>        cpu = raw_smp_processor_id();
> @@ -577,6 +578,8 @@ static void kgdb_wait(struct pt_regs *regs)
>        smp_wmb();
>        atomic_set(&cpu_in_kgdb[cpu], 1);
>
> +       kgdb_disable_hw_debug(regs);
> +
>        /* Wait till primary CPU is done with debugging */
>        while (atomic_read(&passive_cpu_wait[cpu]))
>                cpu_relax();
> @@ -584,6 +587,16 @@ static void kgdb_wait(struct pt_regs *regs)
>        kgdb_info[cpu].debuggerinfo = NULL;
>        kgdb_info[cpu].task = NULL;
>
> +       /* Trap into kgdb as the active CPU if gdb asks to switch. */
> +       thread = getthread(regs, -raw_smp_processor_id() - 2);
> +       if ((arch_kgdb_ops.flags & KGDB_THR_PROC_SWAP) &&
> +               kgdb_contthread && kgdb_contthread == thread) {
> +               kgdb_breakpoint();
> +               clocksource_touch_watchdog();
> +               local_irq_restore(flags);
> +               return;
> +       }
> +
>        /* fix up hardware debug registers on local cpu */
>        if (arch_kgdb_ops.correct_hw_break)
>                arch_kgdb_ops.correct_hw_break();
> @@ -1066,13 +1079,16 @@ static void gdb_cmd_query(struct kgdb_state *ks)
>                        sprintf(tmpstr, "shadowCPU%d",
>                                        (int)(-ks->threadid - 2));
>                        kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
> +
> +                       if (arch_kgdb_ops.flags & KGDB_THR_PROC_SWAP)
> +                               ks->thr_query = 1;
>                }
>                break;
>        }
>  }
>
>  /* Handle the 'H' task query packets */
> -static void gdb_cmd_task(struct kgdb_state *ks)
> +static int gdb_cmd_task(struct kgdb_state *ks)
>  {
>        struct task_struct *thread;
>        char *ptr;
> @@ -1089,6 +1105,15 @@ static void gdb_cmd_task(struct kgdb_state *ks)
>                kgdb_usethread = thread;
>                ks->kgdb_usethreadid = ks->threadid;
>                strcpy(remcom_out_buffer, "OK");
> +#ifdef CONFIG_SMP
> +               if ((arch_kgdb_ops.flags & KGDB_THR_PROC_SWAP) &&
> +                       !ks->thr_query && ks->kgdb_usethreadid < -1 &&
> +                       - ks->kgdb_usethreadid - 2 != raw_smp_processor_id()) {
> +                       kgdb_roundup_cpu(raw_smp_processor_id(), 0);
> +                       kgdb_contthread = kgdb_usethread;
> +                       return 1;
> +               }
> +#endif
>                break;
>        case 'c':
>                ptr = &remcom_in_buffer[2];
> @@ -1106,6 +1131,8 @@ static void gdb_cmd_task(struct kgdb_state *ks)
>                strcpy(remcom_out_buffer, "OK");
>                break;
>        }
> +
> +       return 0;
>  }
>
>  /* Handle the 'T' thread query packets */
> @@ -1114,6 +1141,9 @@ static void gdb_cmd_thread(struct kgdb_state *ks)
>        char *ptr = &remcom_in_buffer[1];
>        struct task_struct *thread;
>
> +       if (arch_kgdb_ops.flags & KGDB_THR_PROC_SWAP)
> +               ks->thr_query = 0;
> +
>        kgdb_hex2long(&ptr, &ks->threadid);
>        thread = getthread(ks->linux_regs, ks->threadid);
>        if (thread)
> @@ -1223,7 +1253,12 @@ static int gdb_serial_stub(struct kgdb_state *ks)
>        /* Clear the out buffer. */
>        memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
>
> -       if (kgdb_connected) {
> +       if ((arch_kgdb_ops.flags & KGDB_THR_PROC_SWAP) && kgdb_contthread) {
> +               remcom_out_buffer[0] = 'O';
> +               remcom_out_buffer[1] = 'K';
> +               remcom_out_buffer[2] = 0;
> +               put_packet(remcom_out_buffer);
> +       } else if (kgdb_connected) {
>                unsigned char thref[8];
>                char *ptr;
>
> @@ -1238,6 +1273,7 @@ static int gdb_serial_stub(struct kgdb_state *ks)
>                put_packet(remcom_out_buffer);
>        }
>
> +       kgdb_contthread = current;
>        kgdb_usethread = kgdb_info[ks->cpu].task;
>        ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
>        ks->pass_exception = 0;
> @@ -1284,7 +1320,8 @@ static int gdb_serial_stub(struct kgdb_state *ks)
>                        gdb_cmd_query(ks);
>                        break;
>                case 'H': /* task related */
> -                       gdb_cmd_task(ks);
> +                       if (gdb_cmd_task(ks))
> +                               goto kgdb_exit;
>                        break;
>                case 'T': /* Query thread status */
>                        gdb_cmd_thread(ks);
> @@ -1324,6 +1361,7 @@ default_handle:
>                        if (error >= 0 || remcom_in_buffer[0] == 'D' ||
>                            remcom_in_buffer[0] == 'k') {
>                                error = 0;
> +                               kgdb_contthread = NULL;
>                                goto kgdb_exit;
>                        }
>
> @@ -1464,11 +1502,15 @@ acquirelock:
>         * Get the passive CPU lock which will hold all the non-primary
>         * CPU in a spin state while the debugger is active
>         */
> -       if (!kgdb_single_step) {
> +       if (!kgdb_single_step && !kgdb_contthread) {
>                for (i = 0; i < NR_CPUS; i++)
>                        atomic_set(&passive_cpu_wait[i], 1);
>        }
>
> +       if (kgdb_contthread)
> +               atomic_set(&passive_cpu_wait[raw_smp_processor_id()], 1);
> +
> +
>        /*
>         * spin_lock code is good enough as a barrier so we don't
>         * need one here:
> @@ -1477,7 +1519,7 @@ acquirelock:
>
>  #ifdef CONFIG_SMP
>        /* Signal the other CPUs to enter kgdb_wait() */
> -       if ((!kgdb_single_step) && kgdb_do_roundup)
> +       if ((!kgdb_single_step && !kgdb_contthread) && kgdb_do_roundup)
>                kgdb_roundup_cpus(flags);
>  #endif
>
> @@ -1496,7 +1538,6 @@ acquirelock:
>        kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
>        kgdb_deactivate_sw_breakpoints();
>        kgdb_single_step = 0;
> -       kgdb_contthread = current;
>        exception_level = 0;
>
>        /* Talk to debugger with gdbserial protocol */
> @@ -1510,7 +1551,14 @@ acquirelock:
>        kgdb_info[ks->cpu].task = NULL;
>        atomic_set(&cpu_in_kgdb[ks->cpu], 0);
>
> -       if (!kgdb_single_step) {
> +#ifdef CONFIG_SMP
> +       i = -(ks->kgdb_usethreadid + 2);
> +       if ((arch_kgdb_ops.flags & KGDB_THR_PROC_SWAP) &&
> +               kgdb_contthread && i != cpu) {
> +               atomic_set(&passive_cpu_wait[i], 0);
> +       }
> +#endif
> +       if (!kgdb_single_step && !kgdb_contthread) {
>                for (i = NR_CPUS-1; i >= 0; i--)
>                        atomic_set(&passive_cpu_wait[i], 0);
>                /*
> @@ -1536,9 +1584,9 @@ kgdb_restore:
>  int kgdb_nmicallback(int cpu, void *regs)
>  {
>  #ifdef CONFIG_SMP
> -       if (!atomic_read(&cpu_in_kgdb[cpu]) &&
> +       if (!atomic_read(&cpu_in_kgdb[cpu]) && (kgdb_contthread ||
>                        atomic_read(&kgdb_active) != cpu &&
> -                       atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) {
> +                       atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)]))) {
>                kgdb_wait((struct pt_regs *)regs);
>                return 0;
>        }
> --
> 1.6.0
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ