diff options
| author | Arnd Bergmann <arnd@arndb.de> | 2016-02-29 13:20:28 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-05-08 07:46:01 +0200 |
| commit | fd79e436325841863d070f8e72246b437c0f5a15 (patch) | |
| tree | aaf860bc6b03c76937f5531ef5c4c00b63db7600 /drivers/mtd | |
| parent | ee6b88767e872fcc7af8e786a05d29d1ba229e75 (diff) | |
mtd: avoid stack overflow in MTD CFI code
commit fddcca5107051adf9e4481d2a79ae0616577fd2c upstream.
When map_word gets too large, we use a lot of kernel stack, and for
MTD_MAP_BANK_WIDTH_32, this means we use more than the recommended
1024 bytes in a number of functions:
drivers/mtd/chips/cfi_cmdset_0020.c: In function 'cfi_staa_write_buffers':
drivers/mtd/chips/cfi_cmdset_0020.c:651:1: warning: the frame size of 1336 bytes is larger than 1024 bytes [-Wframe-larger-than=]
drivers/mtd/chips/cfi_cmdset_0020.c: In function 'cfi_staa_erase_varsize':
drivers/mtd/chips/cfi_cmdset_0020.c:972:1: warning: the frame size of 1208 bytes is larger than 1024 bytes [-Wframe-larger-than=]
drivers/mtd/chips/cfi_cmdset_0001.c: In function 'do_write_buffer':
drivers/mtd/chips/cfi_cmdset_0001.c:1835:1: warning: the frame size of 1240 bytes is larger than 1024 bytes [-Wframe-larger-than=]
This can be avoided if all operations on the map word are done
indirectly and the stack gets reused between the calls. We can
mostly achieve this by selecting MTD_COMPLEX_MAPPINGS whenever
MTD_MAP_BANK_WIDTH_32 is set, but for the case that no other
bank width is enabled, we also need to use a non-constant
map_bankwidth() to convince the compiler to use less stack.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[Brian: this patch mostly achieves its goal by forcing
MTD_COMPLEX_MAPPINGS (and the accompanying indirection) for 256-bit
mappings; the rest of the change is mostly a wash, though it helps
reduce stack size slightly. If we really care about supporting
256-bit mappings though, we should consider rewriting some of this
code to avoid keeping and assigning so many 256-bit objects on the
stack.]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/mtd')
| -rw-r--r-- | drivers/mtd/chips/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/mtd/chips/Kconfig b/drivers/mtd/chips/Kconfig index 54479c481a7a..8a25adced79f 100644 --- a/drivers/mtd/chips/Kconfig +++ b/drivers/mtd/chips/Kconfig @@ -111,6 +111,7 @@ config MTD_MAP_BANK_WIDTH_16 config MTD_MAP_BANK_WIDTH_32 bool "Support 256-bit buswidth" if MTD_CFI_GEOMETRY + select MTD_COMPLEX_MAPPINGS if HAS_IOMEM default n help If you wish to support CFI devices on a physical bus which is |