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

From: Kees Cook
Date: Mon Oct 10 2016 - 19:55:53 EST


On Fri, Oct 7, 2016 at 10:28 PM, Joel Fernandes <joelaf@xxxxxxxxxx> 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@xxxxxxxxxx>
> ---
> 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