On Mon, 16 Sept 2024 at 11:47, Vaishnav Achath vaishnav.a@ti.com wrote:
Hi Prasad,
On 13/09/24 13:02, Prasad Kummari wrote:
Added LMB API to prevent SF command from overwriting reserved memory areas. The current SPI code does not use LMB APIs for loading data into memory addresses. To resolve this, LMB APIs were added to check the load address of an SF command and ensure it does not overwrite reserved memory addresses. Similar checks are used in TFTP, serial load, and boot code to prevent overwriting reserved memory.
Signed-off-by: Prasad Kummari prasad.kummari@amd.com
Changes in V4:
- Removed do_spi_read_lmb_check().
- Added the lmb_read_check() function in lmb.c, making it reusable for NAND, MMC, etc.
- Addressed review comments.
Changes in V3:
- Removed lmb_init_and_reserve() as part of latest LMB series.
- Error message moved to one place.
- lmb_alloc_addr() is not required because the given memory address is being checked to ensure it is free or not.
Changes in V2:
- Rebased the code changes on top of the next branch.
UT: Tested on Versal NET board.
relocaddr = 0x000000007febc000
Versal NET> sf read 0x000000007febc000 0x0 0x40 device 0 offset 0x0, size 0x40 ERROR: trying to overwrite reserved memory... Versal NET> sf write 0x000000007febc000 0x0 0x40 device 0 offset 0x0, size 0x40 ERROR: trying to overwrite reserved memory...
Versal NET> fdt print /reserved-memory reserved-memory { ranges; #size-cells = <0x00000002>; #address-cells = <0x00000002>; tf-a { reg = <0x00000000 0x70000000 0x00000000 0x00050000>; no-map; }; }; Versal NET> sf read 0x70000000 0x0 0x40 device 0 offset 0x0, size 0x40 ERROR: trying to overwrite reserved memory... Versal NET> sf write 0x70000000 0x0 0x40 device 0 offset 0x0, size 0x40 ERROR: trying to overwrite reserved memory... Versal NET> sf erase 0x0 0x1000000;mw.b 0x8000 aabbccdd 0x1000000;sf write 0x8000 0x0 0x1000000;mw.b 0x8008000 0x0 0x1000000;sf read 0x8008000 0x0 0x1000000;cmp.b 0x8000 0x8008000 0x01000000 SF: 16777216 bytes @ 0x0 Erased: OK device 0 offset 0x0, size 0x1000000 SF: 16777216 bytes @ 0x0 Written: OK device 0 offset 0x0, size 0x1000000 SF: 16777216 bytes @ 0x0 Read: OK Total of 16777216 byte(s) were the same
cmd/sf.c | 8 ++++++++ include/lmb.h | 5 +++++ 2 files changed, 13 insertions(+)
diff --git a/cmd/sf.c b/cmd/sf.c index f43a2e08b3..08e364e191 100644 --- a/cmd/sf.c +++ b/cmd/sf.c @@ -10,6 +10,7 @@ #include <div64.h> #include <dm.h> #include <log.h> +#include <lmb.h> #include <malloc.h> #include <mapmem.h> #include <spi.h> @@ -317,6 +318,13 @@ static int do_spi_flash_read_write(int argc, char *const argv[]) strncmp(argv[0], "write", 5) == 0) { int read;
if (CONFIG_IS_ENABLED(LMB)) {if (lmb_read_check(addr, len)) {Even though the function is named lmb_read_check(), it performs an alloc which is never freed, thus it makes it difficult for other callers to use the same region for other purposes (some callers use lmb_get_free_size() ), as mentioned in the commit message the check is only to prevent sf from overwriting reserved region, but it looks like this patch makes the load region also as reserved, is this necessary?
Like I mentioned in my other reply, using a check for lmb_alloc_addr() allows for memory re-use, which is the behaviour that a large number of use cases rely on -- if you go through the test scripts, it is assumed that memory re-use is allowed. That there is no need to explicitly free up memory, and that has been how the LMB memory has been used historically. So it is allowed to use some address to load an image to that address, and then use the same address to load a different image. The LMB rework series does keep this behaviour consistent. So it would be better to change the behaviour of the tftp command to use the same API. I was planning on working on this cleanup. If you want, you can take it up.
printf("ERROR: trying to overwrite reserved memory...\n");return CMD_RET_FAILURE;}}read = strncmp(argv[0], "read", 4) == 0; if (read) ret = spi_flash_read(flash, offset, len, buf);diff --git a/include/lmb.h b/include/lmb.h index fc2daaa7bf..aee2f9fcda 100644 --- a/include/lmb.h +++ b/include/lmb.h @@ -111,6 +111,11 @@ struct lmb *lmb_get(void); int lmb_push(struct lmb *store); void lmb_pop(struct lmb *store);
+static inline int lmb_read_check(phys_addr_t addr, phys_size_t len) +{
return lmb_alloc_addr(addr, len) == addr ? 0 : -1;who frees this? can we free this right after checking?
It is not required to explicitly free up this memory, as it is not an actual allocation per-se. Why were these functions called alloc something, I am not sure. But the point is, if you change the tftp command code to use this API instead, and then use it after a previous load, it would not fail.
-sughosh
Thanks and Regards, Vaishnav
+}
#endif /* __KERNEL__ */
#endif /* _LINUX_LMB_H */