Re: [PATCH v15 01/19] drm/etnaviv: Implement drm_gem_object_funcs::print_info()

From: Lucas Stach
Date: Tue Oct 01 2024 - 09:05:07 EST


Hi Sui,

Am Sonntag, dem 08.09.2024 um 17:43 +0800 schrieb Sui Jingfeng:
> It will be called by drm_gem_print_info() if implemented, and it can
> provide more information about the framebuffer objects.

Etnaviv GEM BOs are not framebuffer objects.

>
> Signed-off-by: Sui Jingfeng <sui.jingfeng@xxxxxxxxx>
> ---
> drivers/gpu/drm/etnaviv/etnaviv_gem.c | 32 +++++++++++++++++++++++++++
> drivers/gpu/drm/etnaviv/etnaviv_gem.h | 2 +-
> 2 files changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
> index 4247a10f8d4f..543d881585b3 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
> @@ -534,8 +534,40 @@ static const struct vm_operations_struct vm_ops = {
> .close = drm_gem_vm_close,
> };
>
> +static const char *etnaviv_gem_obj_caching_info(u32 flags)
> +{
> + switch (flags & ETNA_BO_CACHE_MASK) {
> + case ETNA_BO_CACHED:
> + return "cached";
> + case ETNA_BO_UNCACHED:
> + return "uncached";
> + case ETNA_BO_WC:
> + return "write-combine";

"write-combined" to be consistent with the other two.

> + default:
> + break;
> + }
> +
> + return "unknown";
> +}
> +
> +static void etnaviv_gem_object_info(struct drm_printer *p,
> + unsigned int indent,
> + const struct drm_gem_object *obj)
> +{
> + const struct etnaviv_gem_object *etnaviv_obj;
> +
> + etnaviv_obj = container_of(obj, struct etnaviv_gem_object, base);
> +
> + drm_printf_indent(p, indent, "caching mode=%s\n",
> + etnaviv_gem_obj_caching_info(etnaviv_obj->flags));
> + drm_printf_indent(p, indent, "active=%s\n",
> + str_yes_no(is_active(etnaviv_obj)));
> + drm_printf_indent(p, indent, "vaddr=%p\n", etnaviv_obj->vaddr);

Why should we expose the vaddr to userspace? I don't see why this would
be relevant even as debug info and it leaks the kernel vmap area
address, which could be abused to facilitate kernel exploits.

Regards,
Lucas

> +}
> +
> static const struct drm_gem_object_funcs etnaviv_gem_object_funcs = {
> .free = etnaviv_gem_free_object,
> + .print_info = etnaviv_gem_object_info,
> .pin = etnaviv_gem_prime_pin,
> .unpin = etnaviv_gem_prime_unpin,
> .get_sg_table = etnaviv_gem_prime_get_sg_table,
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.h b/drivers/gpu/drm/etnaviv/etnaviv_gem.h
> index a42d260cac2c..3f8fe19a77cc 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.h
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.h
> @@ -68,7 +68,7 @@ struct etnaviv_gem_ops {
> int (*mmap)(struct etnaviv_gem_object *, struct vm_area_struct *);
> };
>
> -static inline bool is_active(struct etnaviv_gem_object *etnaviv_obj)
> +static inline bool is_active(const struct etnaviv_gem_object *etnaviv_obj)
> {
> return atomic_read(&etnaviv_obj->gpu_active) != 0;
> }