From: Marek Vasut Date: Wed, 27 Jan 2016 02:13:59 +0000 (+0100) Subject: mips: cache: Bulletproof the code against cornercases X-Git-Tag: v2016.03-rc1~14^2~17 X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=fbb0de088b86a0f87e876531b5ae6077cc0ab14c;p=u-boot mips: cache: Bulletproof the code against cornercases This patch makes sure that the flush/invalidate_dcache_range() functions can handle corner-case calls like this -- invalidate_dcache_range(0, 0, 0); This call is valid and is happily produced by USB EHCI code for example. The expected behavior of the cache function(s) in this case is that they will do no operation, since the size is zero. The current implementation though has a problem where such invocation will result in a hard CPU hang. This is because under such conditions, where the start_addr = 0 and stop = 0, the addr = 0 and aend = 0xffffffe0 . The loop will then try to iterate over the entire address space, which in itself is wrong. But iterating over the entire address space might also hit some odd address which will cause bus hang. The later happens on the Atheros MIPS. Signed-off-by: Marek Vasut Cc: Daniel Schwierzeck Cc: Hans de Goede --- diff --git a/arch/mips/lib/cache.c b/arch/mips/lib/cache.c index bf8ff598ac..7482005b67 100644 --- a/arch/mips/lib/cache.c +++ b/arch/mips/lib/cache.c @@ -95,6 +95,10 @@ void flush_dcache_range(ulong start_addr, ulong stop) const void *addr = (const void *)(start_addr & ~(lsize - 1)); const void *aend = (const void *)((stop - 1) & ~(lsize - 1)); + /* aend will be miscalculated when size is zero, so we return here */ + if (start_addr == stop) + return; + while (1) { mips_cache(HIT_WRITEBACK_INV_D, addr); if (addr == aend) @@ -109,6 +113,10 @@ void invalidate_dcache_range(ulong start_addr, ulong stop) const void *addr = (const void *)(start_addr & ~(lsize - 1)); const void *aend = (const void *)((stop - 1) & ~(lsize - 1)); + /* aend will be miscalculated when size is zero, so we return here */ + if (start_addr == stop) + return; + while (1) { mips_cache(HIT_INVALIDATE_D, addr); if (addr == aend)