linux-sg2042/drivers/mtd/chips
Arnd Bergmann fddcca5107 mtd: avoid stack overflow in MTD CFI code
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>
2016-04-03 16:46:24 -07:00
..
Kconfig mtd: avoid stack overflow in MTD CFI code 2016-04-03 16:46:24 -07:00
Makefile [MTD] [CHIPS] Remove MTD_OBSOLETE_CHIPS (jedec, amd_flash, sharp) 2007-05-09 13:34:37 +01:00
cfi_cmdset_0001.c mtd: cfi_cmdset_0001: fixing memory leak and handling failed kmalloc 2016-01-06 17:23:10 -08:00
cfi_cmdset_0002.c mtd: cfi_cmdset_0002: use swap() in cfi_cmdset_0002() 2015-12-18 16:55:28 -08:00
cfi_cmdset_0020.c mtd: cfi: clean up some indenting 2015-03-30 18:01:04 -07:00
cfi_probe.c mtd: cfi: Remove unnecessary OOM messages 2014-03-10 22:42:25 -07:00
cfi_util.c mtd: cfi: deinline large functions 2015-05-27 12:42:16 -07:00
chipreg.c mtd: simplify return logic in do_map_probe() 2012-03-27 00:35:06 +01:00
fwh_lock.h mtd: add leading underscore to all mtd functions 2012-03-27 00:20:01 +01:00
gen_probe.c mtd: gen_probe: Remove unnecessary OOM messages 2014-03-10 22:42:25 -07:00
jedec_probe.c mtd: jedec_probe: fix LH28F640BF definition 2013-08-05 21:04:17 +01:00
map_absent.c mtd: remove retlen zeroing duplication 2012-03-27 00:29:34 +01:00
map_ram.c mtd: map_ram: Enable mtdoops 2015-01-09 15:31:56 -08:00
map_rom.c mtd: map_rom: Support UBI on ROM 2015-01-09 23:24:27 -08:00