From fbb0de088b86a0f87e876531b5ae6077cc0ab14c Mon Sep 17 00:00:00 2001 From: Marek Vasut Date: Wed, 27 Jan 2016 03:13:59 +0100 Subject: [PATCH] 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 --- arch/mips/lib/cache.c | 8 ++++++++ 1 file changed, 8 insertions(+) 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)