From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Schwierzeck Date: Sat, 18 Jul 2015 11:29:33 +0200 Subject: [U-Boot] [Resend RFC PATCH v2] mips: Use unsigned int when reading c0 registers In-Reply-To: <1436871282-5602-2-git-send-email-judge.packham@gmail.com> References: <1436871282-5602-1-git-send-email-judge.packham@gmail.com> <1436871282-5602-2-git-send-email-judge.packham@gmail.com> Message-ID: <55AA1C7D.8010308@gmail.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Am 14.07.2015 um 12:54 schrieb Chris Packham: > In commit a18a477 (MIPS: use common code from lib/time.c) MIPS platforms > started using common the common timer functions which are based around > the fact that many platforms have a 32-bit free running counter register > that can be used see commit 8dfafdd (Introduce common timer functions). > > Even MIPS64 has such a 32-bit register (some have an additional 64-bit free > running counter, but that's something for another time). > > The problem is that in __read_32bit_c0_register() we read the value from > this register into an _signed_ int and as it's returned up the call > chain to timer_read_counter() it gets assigned to an unsigned long. On a > 32-bit system there is no problem. On a 64-bit system odd things happen, > sign extension seems to kick in and all of a sudden if the counter > register happens to have the MSb (i.e. the sign bit) set the negative > int gets sign extended into a very large unsigned long value. This in > turn throws out things from get_ticks() up. > > Update __read_32bit_c0_register() and __read_32bit_c0_ctrl_register() to > use "unsigned int res;" instead of "int res;". There seems to be little > reason to treat these register values as signed. They are either > counters (which by definition are unsigned) or are made up of various > bit fields to be interpreted as per the CPU datasheet. > > Reported-by: Sachin Surendran > Signed-off-by: Chris Packham > > --- > > Changes in v2: > - Use Rob's current email address > > arch/mips/include/asm/mipsregs.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) applied to u-boot-mips/next, thanks -- - Daniel