Date:   Thu, 8 Sep 2016 14:53:05 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Nobuhiro Iwamatsu <nobuhiro.iwamatsu.kw@...achi.com>
Cc:     Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Hiraku Toyooka <hiraku.toyooka.gu@...achi.com>,
        Mark Salyzyn <salyzyn@...roid.com>,
        Seiji Aguchi <seiji.aguchi.tr@...achi.com>
Subject: Re: [PATCH v2 4/5] ramoops: support multiple pmsg instances

On Sun, Jul 24, 2016 at 8:56 PM, Nobuhiro Iwamatsu
<nobuhiro.iwamatsu.kw@...achi.com> wrote:
> From: Hiraku Toyooka <hiraku.toyooka.gu@...achi.com>
>
> This enables ramoops to deal with multiple pmsg instances.
> A User can configure the size of each buffers by its module parameter
> as follows.
>
>   pmsg_size=0x1000,0x2000,...
>
> Then, the ramoops allocates multiple buffers and tells the number
> of buffers to pstore to create multiple /dev/pmsg[ID].
>
> Signed-off-by: Hiraku Toyooka <hiraku.toyooka.gu@...achi.com>
> Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.kw@...achi.com>
> Cc: Mark Salyzyn <salyzyn@...roid.com>
> Cc: Seiji Aguchi <seiji.aguchi.tr@...achi.com>
> ---
>  Documentation/ramoops.txt  |  22 +++++++
>  fs/pstore/ram.c            | 146 ++++++++++++++++++++++++++++++++++++++-------
>  include/linux/pstore_ram.h |   8 ++-
>  3 files changed, 153 insertions(+), 23 deletions(-)
>
> diff --git a/Documentation/ramoops.txt b/Documentation/ramoops.txt
> index 5d86756..cff6ac7 100644
> --- a/Documentation/ramoops.txt
> +++ b/Documentation/ramoops.txt
> @@ -126,3 +126,25 @@ file. Here is an example of usage:
>   0 ffffffff811d9c54  ffffffff8101a7a0  __const_udelay <- native_machine_emergency_restart+0x110/0x1e0
>   0 ffffffff811d9c34  ffffffff811d9c80  __delay <- __const_udelay+0x30/0x40
>   0 ffffffff811d9d14  ffffffff811d9c3f  delay_tsc <- __delay+0xf/0x20
> +
> +6. Pmsg support
> +
> +Ramoops supports pmsg - logging userspace mesages in persistent store. By
> +default, one pmsg area becomes available in ramoops. You can write data into
> +/dev/pmsg0, e.g.:
> +
> + # echo foo > /dev/pmsg0
> +
> +After reboot, the stored data can be read from pmsg-ramoops-0 on the pstore
> +filesystem.
> +
> +You can specify size of the pmsg area by additional kernel command line, e.g.:
> +
> + "ramoops.pmsg_size=0x1000"
> +
> +You can also use multiple pmsg areas, e.g.:
> +
> + "ramoops.pmsg_size=0x1000,0x2000,..."
> +
> +Then, pmsg0, pmsg1, ... will appear on /dev. This is useful to control
> +individual content aging or priority.

The documentation for the DT bindings will need updating too, in:
Documentation/devicetree/bindings/reserved-memory/ramoops.txt

> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index 288c5d0..2bf893f 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -51,8 +51,8 @@ static ulong ramoops_ftrace_size = MIN_MEM_SIZE;
>  module_param_named(ftrace_size, ramoops_ftrace_size, ulong, 0400);
>  MODULE_PARM_DESC(ftrace_size, "size of ftrace log");
>
> -static ulong ramoops_pmsg_size = MIN_MEM_SIZE;
> -module_param_named(pmsg_size, ramoops_pmsg_size, ulong, 0400);
> +static char *ramoops_pmsg_size_str;
> +module_param_named(pmsg_size, ramoops_pmsg_size_str, charp, 0400);
>  MODULE_PARM_DESC(pmsg_size, "size of user space message log");
>
>  static unsigned long long mem_address;
> @@ -86,14 +86,14 @@ struct ramoops_context {
>         struct persistent_ram_zone **dprzs;
>         struct persistent_ram_zone *cprz;
>         struct persistent_ram_zone *fprz;
> -       struct persistent_ram_zone *mprz;
> +       struct persistent_ram_zone **mprzs;
>         phys_addr_t phys_addr;
>         unsigned long size;
>         unsigned int memtype;
>         size_t record_size;
>         size_t console_size;
>         size_t ftrace_size;
> -       size_t pmsg_size;
> +       size_t *pmsg_size;
>         int dump_oops;
>         struct persistent_ram_ecc_info ecc_info;
>         unsigned int max_dump_cnt;
> @@ -103,6 +103,7 @@ struct ramoops_context {
>         unsigned int console_read_cnt;
>         unsigned int ftrace_read_cnt;
>         unsigned int pmsg_read_cnt;
> +       unsigned int num_pmsg;
>         struct pstore_info pstore;
>  };
>
> @@ -220,9 +221,10 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
>         if (!prz_ok(prz))
>                 prz = ramoops_get_next_prz(&cxt->fprz, &cxt->ftrace_read_cnt,
>                                            1, id, type, PSTORE_TYPE_FTRACE, 0);
> -       if (!prz_ok(prz))
> -               prz = ramoops_get_next_prz(&cxt->mprz, &cxt->pmsg_read_cnt,
> -                                          1, id, type, PSTORE_TYPE_PMSG, 0);
> +       while (cxt->pmsg_read_cnt < cxt->num_pmsg && !prz)
> +               prz = ramoops_get_next_prz(cxt->mprzs, &cxt->pmsg_read_cnt,
> +                                          cxt->num_pmsg, id, type,
> +                                          PSTORE_TYPE_PMSG, 0);
>         if (!prz_ok(prz))
>                 return 0;
>
> @@ -286,9 +288,11 @@ static int notrace ramoops_pstore_write_buf(enum pstore_type_id type,
>                 persistent_ram_write(cxt->fprz, buf, size);
>                 return 0;
>         } else if (type == PSTORE_TYPE_PMSG) {
> -               if (!cxt->mprz)
> +               if (part >= cxt->num_pmsg)
> +                       return -EINVAL;
> +               if (!cxt->mprzs || !cxt->mprzs[part])
>                         return -ENOMEM;
> -               persistent_ram_write(cxt->mprz, buf, size);
> +               persistent_ram_write(cxt->mprzs[part], buf, size);
>                 return 0;
>         }
>
> @@ -348,7 +352,9 @@ static int ramoops_pstore_erase(enum pstore_type_id type, u64 id, int count,
>                 prz = cxt->fprz;
>                 break;
>         case PSTORE_TYPE_PMSG:
> -               prz = cxt->mprz;
> +               if (id >= cxt->num_pmsg)
> +                       return -EINVAL;
> +               prz = cxt->mprzs[id];
>                 break;
>         default:
>                 return -EINVAL;
> @@ -426,6 +432,37 @@ fail_prz:
>         return err;
>  }
>
> +static int ramoops_init_mprzs(struct device *dev, struct ramoops_context *cxt,
> +                             phys_addr_t *paddr, unsigned long total)
> +{
> +       int err = -ENOMEM;
> +       int i;
> +
> +       if (!total)
> +               return 0;
> +
> +       if (*paddr + total - cxt->phys_addr > cxt->size) {
> +               dev_err(dev, "no room for pmsg\n");
> +               return -ENOMEM;
> +       }
> +
> +       cxt->mprzs = kcalloc(cxt->num_pmsg, sizeof(*cxt->mprzs), GFP_KERNEL);
> +       if (!cxt->mprzs)
> +               goto fail_prz;
> +
> +       for (i = 0; i < cxt->num_pmsg; i++) {
> +               err = __ramoops_init_prz(dev, cxt, &cxt->mprzs[i], paddr,
> +                                        cxt->pmsg_size[i], 0, true);
> +               if (err)
> +                       goto fail_prz;
> +       }
> +
> +       return 0;
> +fail_prz:
> +       ramoops_free_przs(cxt->mprzs);
> +       return err;
> +}
> +
>  static int ramoops_init_prz(struct device *dev, struct ramoops_context *cxt,
>                             struct persistent_ram_zone **prz,
>                             phys_addr_t *paddr, size_t sz, u32 sig)
> @@ -472,6 +509,8 @@ static int ramoops_probe(struct platform_device *pdev)
>         size_t dump_mem_sz;
>         phys_addr_t paddr;
>         int err = -EINVAL;
> +       unsigned long pmsg_size_total = 0;
> +       unsigned int num_pmsg = 0;
>
>         /* Only a single ramoops area allowed at a time, so fail extra
>          * probes.
> @@ -492,8 +531,18 @@ static int ramoops_probe(struct platform_device *pdev)
>                 pdata->console_size = rounddown_pow_of_two(pdata->console_size);
>         if (pdata->ftrace_size && !is_power_of_2(pdata->ftrace_size))
>                 pdata->ftrace_size = rounddown_pow_of_two(pdata->ftrace_size);
> -       if (pdata->pmsg_size && !is_power_of_2(pdata->pmsg_size))
> -               pdata->pmsg_size = rounddown_pow_of_two(pdata->pmsg_size);
> +       if (pdata->pmsg_size) {
> +               for (;; num_pmsg++) {
> +                       unsigned long size = pdata->pmsg_size[num_pmsg];
> +
> +                       if (!size)
> +                               break;
> +                       if (!is_power_of_2(size))
> +                               pdata->pmsg_size[num_pmsg]
> +                                       = rounddown_pow_of_two(size);
> +                       pmsg_size_total += size;
> +               }
> +       }
>
>         cxt->size = pdata->mem_size;
>         cxt->phys_addr = pdata->mem_address;
> @@ -501,17 +550,26 @@ static int ramoops_probe(struct platform_device *pdev)
>         cxt->record_size = pdata->record_size;
>         cxt->console_size = pdata->console_size;
>         cxt->ftrace_size = pdata->ftrace_size;
> -       cxt->pmsg_size = pdata->pmsg_size;
>         cxt->dump_oops = pdata->dump_oops;
>         cxt->ecc_info = pdata->ecc_info;
> +       cxt->num_pmsg = num_pmsg;
> +       if (num_pmsg) {
> +               cxt->pmsg_size = kcalloc(num_pmsg, sizeof(size_t), GFP_KERNEL);
> +               if (!cxt->pmsg_size) {
> +                       err = -ENOMEM;
> +                       goto fail_out;
> +               }
> +               memcpy(cxt->pmsg_size, pdata->pmsg_size,
> +                      sizeof(size_t) * num_pmsg);
> +       }
>
>         paddr = cxt->phys_addr;
>
>         dump_mem_sz = cxt->size - cxt->console_size - cxt->ftrace_size
> -                       - cxt->pmsg_size;
> +                       - pmsg_size_total;
>         err = ramoops_init_dprzs(dev, cxt, &paddr, dump_mem_sz);
>         if (err)
> -               goto fail_out;
> +               goto fail_init_dprzs;
>
>         err = ramoops_init_prz(dev, cxt, &cxt->cprz, &paddr,
>                                cxt->console_size, 0);
> @@ -523,11 +581,12 @@ static int ramoops_probe(struct platform_device *pdev)
>         if (err)
>                 goto fail_init_fprz;
>
> -       err = ramoops_init_prz(dev, cxt, &cxt->mprz, &paddr, cxt->pmsg_size, 0);
> +       err = ramoops_init_mprzs(dev, cxt, &paddr, pmsg_size_total);
>         if (err)
> -               goto fail_init_mprz;
> +               goto fail_init_mprzs;
>
>         cxt->pstore.data = cxt;
> +       cxt->pstore.num_pmsg = num_pmsg;
>         /*
>          * Console can handle any buffer size, so prefer LOG_LINE_MAX. If we
>          * have to handle dumps, we must have at least record_size buffer. And
> @@ -560,7 +619,6 @@ static int ramoops_probe(struct platform_device *pdev)
>         record_size = pdata->record_size;
>         dump_oops = pdata->dump_oops;
>         ramoops_console_size = pdata->console_size;
> -       ramoops_pmsg_size = pdata->pmsg_size;

Doesn't this mean the module parameters for the pmsg_size list won't
be visible to sysfs?

>         ramoops_ftrace_size = pdata->ftrace_size;
>
>         pr_info("attached 0x%lx@...llx, ecc: %d/%d\n",
> @@ -573,14 +631,16 @@ fail_buf:
>         kfree(cxt->pstore.buf);
>  fail_clear:
>         cxt->pstore.bufsize = 0;
> -       persistent_ram_free(cxt->mprz);
> -fail_init_mprz:
> +       ramoops_free_przs(cxt->mprzs);
> +fail_init_mprzs:
>         persistent_ram_free(cxt->fprz);
>  fail_init_fprz:
>         persistent_ram_free(cxt->cprz);
>  fail_init_cprz:
>         cxt->max_dump_cnt = 0;
>         ramoops_free_przs(cxt->dprzs);
> +fail_init_dprzs:
> +       kfree(cxt->pmsg_size);
>  fail_out:
>         return err;
>  }
> @@ -594,8 +654,9 @@ static int ramoops_remove(struct platform_device *pdev)
>
>         kfree(cxt->pstore.buf);
>         cxt->pstore.bufsize = 0;
> +       kfree(cxt->pmsg_size);
>
> -       persistent_ram_free(cxt->mprz);
> +       ramoops_free_przs(cxt->mprzs);
>         persistent_ram_free(cxt->fprz);
>         persistent_ram_free(cxt->cprz);
>         ramoops_free_przs(cxt->dprzs);
> @@ -611,6 +672,38 @@ static struct platform_driver ramoops_driver = {
>         },
>  };
>
> +static unsigned long *parse_size_str(char *size_str)
> +{
> +       int i, ret;
> +       unsigned long *size_array, count = 1;
> +
> +       if (size_str) {
> +               char *s = size_str;
> +               /* Necessary array size is the number of commas + 1 */
> +               for (; (s = strchr(s, ',')); s++)
> +                       count++;
> +       }
> +
> +       size_array = kcalloc(count + 1, sizeof(unsigned long), GFP_KERNEL);
> +       if (!size_array)
> +               goto out;
> +
> +       if (size_str) {
> +               for (i = 0; i < count; i++) {
> +                       ret = get_option(&size_str, (int *)&size_array[i]);
> +                       if (ret == 1)
> +                               break;
> +                       else if (ret != 2) {
> +                               size_array[i] = 0;
> +                               break;
> +                       }
> +               }
> +       } else
> +               size_array[0] = MIN_MEM_SIZE;
> +out:
> +       return size_array;
> +}
> +
>  static void ramoops_register_dummy(void)
>  {
>         if (!mem_size)
> @@ -630,7 +723,9 @@ static void ramoops_register_dummy(void)
>         dummy_data->record_size = record_size;
>         dummy_data->console_size = ramoops_console_size;
>         dummy_data->ftrace_size = ramoops_ftrace_size;
> -       dummy_data->pmsg_size = ramoops_pmsg_size;
> +       dummy_data->pmsg_size = parse_size_str(ramoops_pmsg_size_str);

I think this function is wrong, since it looks like the num_pmsg count
a bit above expects to find a NULL-terminated list. I think
parse_size_str() needs to include an extra empty array allocation to
make sure the list is always NULL-terminated.

> +       if (!dummy_data->pmsg_size)
> +               goto fail_pmsg_size;
>         dummy_data->dump_oops = dump_oops;
>         /*
>          * For backwards compatibility ramoops.ecc=1 means 16 bytes ECC
> @@ -643,7 +738,13 @@ static void ramoops_register_dummy(void)
>         if (IS_ERR(dummy)) {
>                 pr_info("could not create platform device: %ld\n",
>                         PTR_ERR(dummy));
> +               goto fail_pdev;
>         }
> +       return;
> +fail_pdev:
> +       kfree(dummy_data->pmsg_size);
> +fail_pmsg_size:
> +       kfree(dummy_data);
>  }
>
>  static int __init ramoops_init(void)
> @@ -657,6 +758,7 @@ static void __exit ramoops_exit(void)
>  {
>         platform_driver_unregister(&ramoops_driver);
>         platform_device_unregister(dummy);
> +       kfree(dummy_data->pmsg_size);
>         kfree(dummy_data);
>  }
>  module_exit(ramoops_exit);
> diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h
> index 4660aaa..af7bbdd 100644
> --- a/include/linux/pstore_ram.h
> +++ b/include/linux/pstore_ram.h
> @@ -72,6 +72,12 @@ ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
>   * Ramoops platform data
>   * @mem_size   memory size for ramoops
>   * @mem_address        physical memory address to contain ramoops
> + * @pmsg_size  array containing size of each pmsg area. 0 value in the array
> + *             indicates the end of the content. For example, if the following
> + *             array is given,
> + *                 .pmsg_size = { 0x1000, 0x2000, 0x0, 0x3000, };
> + *             then, pmsg areas are allocated for the first two size values
> + *             and '0x3000' is just ignored.
>   */
>
>  struct ramoops_platform_data {
> @@ -81,7 +87,7 @@ struct ramoops_platform_data {
>         unsigned long   record_size;
>         unsigned long   console_size;
>         unsigned long   ftrace_size;
> -       unsigned long   pmsg_size;
> +       unsigned long   *pmsg_size;
>         int             dump_oops;
>         struct persistent_ram_ecc_info ecc_info;
>  };
> --
> 2.8.1
>
>

-Kees

-- 
Kees Cook
Nexus Security

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