On Tue, Feb 11, 2020 at 01:09:40PM -0700, Simon Glass wrote:
> Support ASSUME_VALID_DTB to disable some sanity checks
>
> If we assume that the DTB itself is valid then we can skip some checks and
> save code space. Add various conditions to handle this.
>
> Signed-off-by: Simon Glass <sjg@xxxxxxxxxxxx>
> ---
>
> Changes in v6:
> - Always call fdt_ro_probe_(), etc. and have that function do the check
> - Change check in fdt_get_property_namelen_() to VALID_DTB
>
> Changes in v5:
> - Split out VALID_DTB checks into a separate patch
>
> Changes in v4: None
> Changes in v3: None
> Changes in v2: None
>
> libfdt/fdt.c | 53 +++++++++++++++++++++++++++++--------------------
> libfdt/fdt_ro.c | 3 ++-
> libfdt/fdt_rw.c | 2 ++
> libfdt/fdt_sw.c | 19 +++++++++++-------
> 4 files changed, 47 insertions(+), 30 deletions(-)
>
> diff --git a/libfdt/fdt.c b/libfdt/fdt.c
> index 3e37a4b..d4daf60 100644
> --- a/libfdt/fdt.c
> +++ b/libfdt/fdt.c
> @@ -19,6 +19,9 @@ int32_t fdt_ro_probe_(const void *fdt)
> {
> uint32_t totalsize = fdt_totalsize(fdt);
>
> + if (can_assume(VALID_DTB))
> + return totalsize;
> +
> if (fdt_magic(fdt) == FDT_MAGIC) {
> /* Complete tree */
> if (fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
> @@ -81,38 +84,44 @@ int fdt_check_header(const void *fdt)
>
> if (fdt_magic(fdt) != FDT_MAGIC)
> return -FDT_ERR_BADMAGIC;
> - hdrsize = fdt_header_size(fdt);
> if ((fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION)
> || (fdt_last_comp_version(fdt) > FDT_LAST_SUPPORTED_VERSION))
> return -FDT_ERR_BADVERSION;
> if (fdt_version(fdt) < fdt_last_comp_version(fdt))
> return -FDT_ERR_BADVERSION;
> + hdrsize = fdt_header_size(fdt);
> + if (!can_assume(VALID_DTB)) {
>
> - if ((fdt_totalsize(fdt) < hdrsize)
> - || (fdt_totalsize(fdt) > INT_MAX))
> - return -FDT_ERR_TRUNCATED;
> -
> - /* Bounds check memrsv block */
> - if (!check_off_(hdrsize, fdt_totalsize(fdt), fdt_off_mem_rsvmap(fdt)))
> - return -FDT_ERR_TRUNCATED;
> + if ((fdt_totalsize(fdt) < hdrsize)
> + || (fdt_totalsize(fdt) > INT_MAX))
> + return -FDT_ERR_TRUNCATED;
>
> - /* Bounds check structure block */
> - if (fdt_version(fdt) < 17) {
> + /* Bounds check memrsv block */
> if (!check_off_(hdrsize, fdt_totalsize(fdt),
> - fdt_off_dt_struct(fdt)))
> + fdt_off_mem_rsvmap(fdt)))
> return -FDT_ERR_TRUNCATED;
> - } else {
> + }
> +
> + if (!can_assume(VALID_DTB)) {
> + /* Bounds check structure block */
> + if (fdt_version(fdt) < 17) {
> + if (!check_off_(hdrsize, fdt_totalsize(fdt),
> + fdt_off_dt_struct(fdt)))
> + return -FDT_ERR_TRUNCATED;
> + } else {
> + if (!check_block_(hdrsize, fdt_totalsize(fdt),
> + fdt_off_dt_struct(fdt),
> + fdt_size_dt_struct(fdt)))
> + return -FDT_ERR_TRUNCATED;
> + }
> +
> + /* Bounds check strings block */
> if (!check_block_(hdrsize, fdt_totalsize(fdt),
> - fdt_off_dt_struct(fdt),
> - fdt_size_dt_struct(fdt)))
> + fdt_off_dt_strings(fdt),
> + fdt_size_dt_strings(fdt)))
> return -FDT_ERR_TRUNCATED;
> }
>
> - /* Bounds check strings block */
> - if (!check_block_(hdrsize, fdt_totalsize(fdt),
> - fdt_off_dt_strings(fdt), fdt_size_dt_strings(fdt)))
> - return -FDT_ERR_TRUNCATED;
> -
> return 0;
> }
>
> @@ -142,7 +151,7 @@ uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
>
> *nextoffset = -FDT_ERR_TRUNCATED;
> tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
> - if (!tagp)
> + if (!can_assume(VALID_DTB) && !tagp)
> return FDT_END; /* premature end */
> tag = fdt32_to_cpu(*tagp);
> offset += FDT_TAGSIZE;
> @@ -154,13 +163,13 @@ uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
> do {
> p = fdt_offset_ptr(fdt, offset++, 1);
> } while (p && (*p != '\0'));
> - if (!p)
> + if (!can_assume(VALID_DTB) && !p)
> return FDT_END; /* premature end */
> break;
>
> case FDT_PROP:
> lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
> - if (!lenp)
> + if (!can_assume(VALID_DTB) && !lenp)
> return FDT_END; /* premature end */
> /* skip-name offset, length and value */
> offset += sizeof(struct fdt_property) - FDT_TAGSIZE
> diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
> index a5c2797..4c26fbe 100644
> --- a/libfdt/fdt_ro.c
> +++ b/libfdt/fdt_ro.c
> @@ -388,7 +388,8 @@ static const struct fdt_property *fdt_get_property_namelen_(const void *fdt,
> (offset = fdt_next_property_offset(fdt, offset))) {
> const struct fdt_property *prop;
>
> - if (!(prop = fdt_get_property_by_offset_(fdt, offset, lenp))) {
> + prop = fdt_get_property_by_offset_(fdt, offset, lenp);
> + if (!can_assume(VALID_DTB) && !prop) {
> offset = -FDT_ERR_INTERNAL;
> break;
> }
> diff --git a/libfdt/fdt_rw.c b/libfdt/fdt_rw.c
> index 8795947..707c00a 100644
> --- a/libfdt/fdt_rw.c
> +++ b/libfdt/fdt_rw.c
> @@ -24,6 +24,8 @@ static int fdt_blocks_misordered_(const void *fdt,
>
> static int fdt_rw_probe_(void *fdt)
> {
> + if (can_assume(VALID_DTB))
> + return 0;
> FDT_RO_PROBE(fdt);
>
> if (fdt_version(fdt) < 17)
> diff --git a/libfdt/fdt_sw.c b/libfdt/fdt_sw.c
> index 76bea22..96365b4 100644
> --- a/libfdt/fdt_sw.c
> +++ b/libfdt/fdt_sw.c
> @@ -12,10 +12,13 @@
>
> static int fdt_sw_probe_(void *fdt)
> {
> - if (fdt_magic(fdt) == FDT_MAGIC)
> - return -FDT_ERR_BADSTATE;
> - else if (fdt_magic(fdt) != FDT_SW_MAGIC)
> - return -FDT_ERR_BADMAGIC;
> + if (!can_assume(VALID_DTB)) {
> + if (fdt_magic(fdt) == FDT_MAGIC)
> + return -FDT_ERR_BADSTATE;
> + else if (fdt_magic(fdt) != FDT_SW_MAGIC)
> + return -FDT_ERR_BADMAGIC;
> + }
> +
> return 0;
> }
>
> @@ -38,7 +41,7 @@ static int fdt_sw_probe_memrsv_(void *fdt)
> if (err)
> return err;
>
> - if (fdt_off_dt_strings(fdt) != 0)
> + if (!can_assume(VALID_DTB) && fdt_off_dt_strings(fdt) != 0)
> return -FDT_ERR_BADSTATE;
> return 0;
> }
> @@ -46,7 +49,8 @@ static int fdt_sw_probe_memrsv_(void *fdt)
> #define FDT_SW_PROBE_MEMRSV(fdt) \
> { \
> int err; \
> - if ((err = fdt_sw_probe_memrsv_(fdt)) != 0) \
> + if (!can_assume(VALID_DTB) && \
> + (err = fdt_sw_probe_memrsv_(fdt)) != 0) \
Nit: with the can_assume() inside fdt_sw_probe_memrsv_(), I don't
think you need it here as well.
Otherwise, LGTM.
> return err; \
> }
>
> @@ -151,7 +155,8 @@ int fdt_resize(void *fdt, void *buf, int bufsize)
> headsize = fdt_off_dt_struct(fdt) + fdt_size_dt_struct(fdt);
> tailsize = fdt_size_dt_strings(fdt);
>
> - if ((headsize + tailsize) > fdt_totalsize(fdt))
> + if (!can_assume(VALID_DTB) &&
> + headsize + tailsize > fdt_totalsize(fdt))
> return -FDT_ERR_INTERNAL;
>
> if ((headsize + tailsize) > bufsize)
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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