Re: [REBASE PATCH v5 10/17] pstore: Add pstore_region_defined() helper and export it

Kees Cook
2023-09-13T23:24:08Z

On Mon, Sep 11, 2023 at 04:23:52PM +0530, Mukesh Ojha wrote:
> There are users like Qualcomm minidump which is interested in
> knowing the pstore frontend addresses and sizes from the backend
> (ram) to be able to register it with firmware to finally collect
> them during crash for debugging.
>
> Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
> ---
> fs/pstore/platform.c | 15 +++++++++++++++
> fs/pstore/ram.c | 42 ++++++++++++++++++++++++++++++++++++++++++
> include/linux/pstore.h | 6 ++++++
> 3 files changed, 63 insertions(+)
>
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index e5bca9a004cc..fdac951059c1 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -139,6 +139,21 @@ enum pstore_type_id pstore_name_to_type(const char *name)
> }
> EXPORT_SYMBOL_GPL(pstore_name_to_type);
>
> +int pstore_region_defined(struct pstore_record *record,
> + void **virt, phys_addr_t *phys,
> + size_t *size, unsigned int *max_dump_cnt)
> +{
> + if (!psinfo)
> + return -EINVAL;
> +
> + record->psi = psinfo;

Uh, this makes no sense to me. If this is a real pstore_record, you
cannot just assign psi here.

> +
> + return psinfo->region_info ?
> + psinfo->region_info(record, virt, phys, size, max_dump_cnt) :
> + -EINVAL;

Common code style for this kind of thing is usually like this:

if (!psinfo->region_info)
return -EINVAL;

return psinfo->region_info(...)

> +}
> +EXPORT_SYMBOL_GPL(pstore_region_defined);
> +
> static void pstore_timer_kick(void)
> {
> if (pstore_update_ms < 0)
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index ab551caa1d2a..62202f3ddf63 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -437,6 +437,47 @@ static int ramoops_pstore_erase(struct pstore_record *record)
> return 0;
> }
>
> +static int ramoops_region_info(struct pstore_record *record,
> + void **virt, phys_addr_t *phys,
> + size_t *size, unsigned int *max_dump_cnt)

But there's a larger problem here -- "virt", "phys" and likely
"max_dump_cnt" are aspects _specific to the ram backend_. This can't be
a generic pstore interface.

I'm not opposed to it being exposed only from ramoops, though.

But I think you'll want a pstore generic way to iterate over the
records...

--
Kees Cook