Am 27.01.2016 um 03:13 schrieb Marek Vasut:
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 marex@denx.de Cc: Daniel Schwierzeck daniel.schwierzeck@gmail.com Cc: Hans de Goede hdegoede@redhat.com
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 bf8ff59..7482005 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;
you could additionally move the initialization of addr and aend behind this check like it's done in flush_cache()? That would save some CPU cycles.
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)