Re: [PATCH 4/7] pstore: Make ramoops_init_przs generic for other prz arrays

[Kees Cook <keescook@chromium.org>]

On Fri, Oct 7, 2016 at 10:28 PM, Joel Fernandes <joelaf@google.com> wrote:
> Currently ramoops_init_przs is hard wired only for panic dump zone array. In
> preparation for the ftrace zone array (one zone per-cpu), make the function
> more generic to be able to handle this case.
>
> Add a new ramoops_init_dump_przs function and use the generic function for the
> dump prz array.

Something similar was suggested in the recent "multiple pmsg" series
that was posted too. Making this generic is good, though see my nit
below...

>
> Signed-off-by: Joel Fernandes <joelaf@google.com>
> ---
>  fs/pstore/ram.c | 72 ++++++++++++++++++++++++++++++++++++---------------------
>  1 file changed, 46 insertions(+), 26 deletions(-)
>
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index 519404c..a796f49 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -402,54 +402,74 @@ static void ramoops_free_przs(struct ramoops_context *cxt)
>  }
>
>  static int ramoops_init_przs(struct device *dev, struct ramoops_context *cxt,
> -                            phys_addr_t *paddr, size_t dump_mem_sz)
> +                            struct persistent_ram_zone ***przs,
> +                            phys_addr_t *paddr, size_t mem_sz,
> +                            unsigned int cnt, u32 sig)
>  {
>         int err = -ENOMEM;
>         int i;
> +       size_t zone_sz;
> +       struct persistent_ram_zone **prz_ar;
>
> -       if (!cxt->record_size)
> -               return 0;
> -
> -       if (*paddr + dump_mem_sz - cxt->phys_addr > cxt->size) {
> -               dev_err(dev, "no room for dumps\n");
> +       if (*paddr + mem_sz - cxt->phys_addr > cxt->size) {
> +               dev_err(dev, "no room for mem region (0x%zx@0x%llx) in (0x%lx@0x%llx)\n",
> +                       mem_sz, (unsigned long long)*paddr,
> +                       cxt->size, (unsigned long long)cxt->phys_addr);
>                 return -ENOMEM;
>         }
>
> -       cxt->max_dump_cnt = dump_mem_sz / cxt->record_size;
> -       if (!cxt->max_dump_cnt)
> +       zone_sz = mem_sz / cnt;
> +       if (!zone_sz)
>                 return -ENOMEM;
>
> -       cxt->przs = kzalloc(sizeof(*cxt->przs) * cxt->max_dump_cnt,
> -                            GFP_KERNEL);
> -       if (!cxt->przs) {
> -               dev_err(dev, "failed to initialize a prz array for dumps\n");
> -               goto fail_mem;
> +       prz_ar = kzalloc(sizeof(**przs) * cnt, GFP_KERNEL);

While I realize this is mainly a refactoring, as long as we're in
here, can you make this kcalloc instead?

> +       if (!prz_ar) {
> +               dev_err(dev, "Failed to initialize prz array\n");
> +               return -ENOMEM;
>         }
>
> -       for (i = 0; i < cxt->max_dump_cnt; i++) {
> -               cxt->przs[i] = persistent_ram_new(*paddr, cxt->record_size, 0,
> +       for (i = 0; i < cnt; i++) {
> +               prz_ar[i] = persistent_ram_new(*paddr, zone_sz, sig,
>                                                   &cxt->ecc_info,
>                                                   cxt->memtype);
> -               if (IS_ERR(cxt->przs[i])) {
> -                       err = PTR_ERR(cxt->przs[i]);
> +               if (IS_ERR(prz_ar[i])) {
> +                       err = PTR_ERR(prz_ar[i]);
>                         dev_err(dev, "failed to request mem region (0x%zx@0x%llx): %d\n",
>                                 cxt->record_size, (unsigned long long)*paddr, err);
>
>                         while (i > 0) {
>                                 i--;
> -                               persistent_ram_free(cxt->przs[i]);
> +                               persistent_ram_free(prz_ar[i]);
>                         }
> -                       goto fail_prz;
> +                       kfree(prz_ar);
> +                       return err;
>                 }
> -               *paddr += cxt->record_size;
> +               *paddr += zone_sz;
>         }
>
> +       *przs = prz_ar;
>         return 0;
> -fail_prz:
> -       kfree(cxt->przs);
> -fail_mem:
> -       cxt->max_dump_cnt = 0;
> -       return err;
> +}
> +
> +static int ramoops_init_dump_przs(struct device *dev,
> +                                 struct ramoops_context *cxt,
> +                                 phys_addr_t *paddr, size_t mem_sz)
> +{
> +       int ret;
> +
> +       if (!cxt->record_size)
> +               return 0;
> +
> +       cxt->max_dump_cnt = mem_sz / cxt->record_size;
> +       if (!cxt->max_dump_cnt)
> +               return -ENOMEM;
> +
> +       ret = ramoops_init_przs(dev, cxt, &cxt->przs, paddr, mem_sz,
> +                               cxt->max_dump_cnt, 0);
> +       if (ret)
> +               cxt->max_dump_cnt = 0;
> +
> +       return ret;
>  }
>
>  static int ramoops_init_prz(struct device *dev, struct ramoops_context *cxt,
> @@ -601,7 +621,7 @@ static int ramoops_probe(struct platform_device *pdev)
>
>         dump_mem_sz = cxt->size - cxt->console_size - cxt->ftrace_size
>                         - cxt->pmsg_size;
> -       err = ramoops_init_przs(dev, cxt, &paddr, dump_mem_sz);
> +       err = ramoops_init_dump_przs(dev, cxt, &paddr, dump_mem_sz);
>         if (err)
>                 goto fail_out;
>
> --
> 2.7.4
>

-Kees

-- 
Kees Cook
Nexus Security