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596fd46268
We don't need to open code the divide function, just use div_u64 that already exists and do the same job. While this is a straightforward clean up, there is more to that, the real motivation for this. While building on a cross compiling environment in armel, using gcc 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5), I was getting the following build error: ERROR: "__aeabi_uldivmod" [drivers/mtd/nand/nandsim.ko] undefined! After investigating with objdump and hand built assembly version generated with the compiler, I narrowed __aeabi_uldivmod as being generated from the divide function. When nandsim.c is built with -fno-inline-functions-called-once, that happens when CONFIG_DEBUG_SECTION_MISMATCH is enabled, the do_div optimization in arch/arm/include/asm/div64.h doesn't work as expected with the open coded divide function: even if the do_div we are using doesn't have a constant divisor, the compiler still includes the else parts of the optimized do_div macro, and translates the divisions there to use __aeabi_uldivmod, instead of only calling __do_div_asm -> __do_div64 and optimizing/removing everything else out. So to reproduce, gcc 4.6 plus CONFIG_DEBUG_SECTION_MISMATCH=y and CONFIG_MTD_NAND_NANDSIM=m should do it, building on armel. After this change, the compiler does the intended thing even with -fno-inline-functions-called-once, and optimizes out as expected the constant handling in the optimized do_div on arm. As this also avoids a build issue, I'm marking for Stable, as I think is applicable for this case. Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com> Cc: stable@vger.kernel.org Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> |
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| .. | ||
| chips | ||
| devices | ||
| lpddr | ||
| maps | ||
| nand | ||
| onenand | ||
| tests | ||
| ubi | ||
| afs.c | ||
| ar7part.c | ||
| bcm63xxpart.c | ||
| cmdlinepart.c | ||
| ftl.c | ||
| inftlcore.c | ||
| inftlmount.c | ||
| Kconfig | ||
| Makefile | ||
| mtd_blkdevs.c | ||
| mtdblock_ro.c | ||
| mtdblock.c | ||
| mtdchar.c | ||
| mtdconcat.c | ||
| mtdcore.c | ||
| mtdcore.h | ||
| mtdoops.c | ||
| mtdpart.c | ||
| mtdsuper.c | ||
| mtdswap.c | ||
| nftlcore.c | ||
| nftlmount.c | ||
| ofpart.c | ||
| redboot.c | ||
| rfd_ftl.c | ||
| sm_ftl.c | ||
| sm_ftl.h | ||
| ssfdc.c | ||