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misc: fastrpc: avoid duplicate DMA mappings in fastrpc_create_maps() #774

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misc: fastrpc: avoid duplicate DMA mappings in fastrpc_create_maps() #774

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56 changes: 41 additions & 15 deletions drivers/misc/fastrpc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -238,6 +238,7 @@ struct fastrpc_map {
u64 len;
u64 raddr;
u32 attr;
u32 flags;
struct kref refcount;
};

Expand Down Expand Up @@ -869,7 +870,7 @@ static const struct dma_buf_ops fastrpc_dma_buf_ops = {
};

static int fastrpc_map_attach(struct fastrpc_user *fl, int fd,
u64 len, u32 attr, struct fastrpc_map **ppmap)
u64 len, u32 attr, struct fastrpc_map **ppmap, int mflags)
{
struct fastrpc_session_ctx *sess = fl->sctx;
struct fastrpc_map *map = NULL;
Expand All @@ -886,6 +887,7 @@ static int fastrpc_map_attach(struct fastrpc_user *fl, int fd,

map->fl = fl;
map->fd = fd;
map->flags = mflags;
map->buf = dma_buf_get(fd);
if (IS_ERR(map->buf)) {
err = PTR_ERR(map->buf);
Expand Down Expand Up @@ -961,13 +963,13 @@ static int fastrpc_map_attach(struct fastrpc_user *fl, int fd,
return err;
}

static int fastrpc_map_create(struct fastrpc_user *fl, int fd,
u64 len, u32 attr, struct fastrpc_map **ppmap)
static int fastrpc_map_create(struct fastrpc_user *fl, int fd, u64 len, u32 attr,
struct fastrpc_map **ppmap, bool take_ref, int mflags)
{
if (!fastrpc_map_lookup(fl, fd, ppmap, true))
if (!fastrpc_map_lookup(fl, fd, ppmap, take_ref))
return 0;

return fastrpc_map_attach(fl, fd, len, attr, ppmap);
return fastrpc_map_attach(fl, fd, len, attr, ppmap, mflags);
}

/*
Expand Down Expand Up @@ -1038,23 +1040,25 @@ static int fastrpc_create_maps(struct fastrpc_invoke_ctx *ctx)
int i, err;

for (i = 0; i < ctx->nscalars; ++i) {
bool take_ref = i < ctx->nbufs;
int mflags = 0;

if (ctx->args[i].fd == 0 || ctx->args[i].fd == -1 ||
ctx->args[i].length == 0)
continue;

if (i < ctx->nbufs)
err = fastrpc_map_create(ctx->fl, ctx->args[i].fd,
ctx->args[i].length, ctx->args[i].attr, &ctx->maps[i]);
else
err = fastrpc_map_attach(ctx->fl, ctx->args[i].fd,
ctx->args[i].length, ctx->args[i].attr, &ctx->maps[i]);
/* Set the DMA handle mapping flag for DMA handles */
if (i >= ctx->nbufs)
mflags = FASTRPC_MAP_DMA_HANDLE;

err = fastrpc_map_create(ctx->fl, ctx->args[i].fd, ctx->args[i].length,
ctx->args[i].attr, &ctx->maps[i], take_ref, mflags);
if (err) {
dev_err(dev, "Error Creating map %d\n", err);
return -EINVAL;
}

}

return 0;
}

Expand Down Expand Up @@ -1247,6 +1251,16 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
list[i].num = ctx->args[i].length ? 1 : 0;
list[i].pgidx = i;
if (ctx->maps[i]) {
/* It is possible that map is created with
* mflags FASTRPC_MAP_DMA_HANDLE and take_ref
* is false. Check if map still exists or is
* being freed as take_ref is false
*/
if (fastrpc_map_lookup(ctx->fl, ctx->args[i].fd,
&ctx->maps[i], false)) {
ctx->maps[i] = NULL;
return -EINVAL;
}
pages[i].addr = ctx->maps[i]->phys;
pages[i].size = ctx->maps[i]->size;
}
Expand Down Expand Up @@ -1296,8 +1310,13 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
for (i = 0; i < FASTRPC_MAX_FDLIST; i++) {
if (!fdlist[i])
break;
if (!fastrpc_map_lookup(fl, (int)fdlist[i], &mmap, false))
/* Validate the map flags for DMA handles and skip freeing map if invalid */
if (!fastrpc_map_lookup(fl, (int)fdlist[i], &mmap, false) &&
mmap->flags == FASTRPC_MAP_DMA_HANDLE) {
/* Allow DMA handle maps to free only once */
mmap->flags = 0;
fastrpc_map_put(mmap);
}
}

return ret;
Expand Down Expand Up @@ -1649,7 +1668,7 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl,
fl->pd = USER_PD;

if (init.filelen && init.filefd) {
err = fastrpc_map_create(fl, init.filefd, init.filelen, 0, &map);
err = fastrpc_map_create(fl, init.filefd, init.filelen, 0, &map, true, 0);
if (err)
goto err;
}
Expand Down Expand Up @@ -2275,8 +2294,15 @@ static int fastrpc_req_mem_map(struct fastrpc_user *fl, char __user *argp)
if (copy_from_user(&req, argp, sizeof(req)))
return -EFAULT;

/*
* Prevent mapping backward compatible DMA handles here, as they are
* already mapped in the remote call.
*/
if (req.flags == FASTRPC_MAP_DMA_HANDLE)
return -EINVAL;

/* create SMMU mapping */
err = fastrpc_map_create(fl, req.fd, req.length, 0, &map);
err = fastrpc_map_create(fl, req.fd, req.length, 0, &map, true, 0);
if (err) {
dev_err(dev, "failed to map buffer, fd = %d\n", req.fd);
return err;
Expand Down
2 changes: 2 additions & 0 deletions include/uapi/misc/fastrpc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,8 @@ enum fastrpc_map_flags {
FASTRPC_MAP_FD = 2,
FASTRPC_MAP_FD_DELAYED,
FASTRPC_MAP_FD_NOMAP = 16,
/* Map the DMA handle in the invoke call for backward compatibility */
FASTRPC_MAP_DMA_HANDLE = 0x20000,
FASTRPC_MAP_MAX,
};

Expand Down