Re: [PATCH v7 05/11] arm64: perf: Include threshold control fields in PMEVTYPER mask

[James Clark]

On 15/12/2023 12:08, Uwe Kleine-König wrote:
> Hello,
> 
> On Mon, Dec 11, 2023 at 04:13:17PM +0000, James Clark wrote:
>> FEAT_PMUv3_TH (Armv8.8) adds two new fields to PMEVTYPER, so include
>> them in the mask. These aren't writable on 32 bit kernels as they are in
>> the high part of the register, so only include them for arm64.
>>
>> It would be difficult to do this statically in the asm header files for
>> each platform without resulting in circular includes or #ifdefs inline
>> in the code. For that reason the ARMV8_PMU_EVTYPE_MASK definition has
>> been removed and the mask is constructed programmatically.
>>
>> Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
>> Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
>> Signed-off-by: James Clark <james.clark@xxxxxxx>
> 
> This change is in today's next as commit
> 3115ee021bfb04efde2e96507bfcc1330261a6a1. this breaks allmodconfig
> building on ARCH=arm:
> 
> 	In file included from include/linux/ratelimit_types.h:5,
> 			 from include/linux/printk.h:9,
> 			 from include/asm-generic/bug.h:22,
> 			 from arch/arm/include/asm/bug.h:60,
> 			 from include/linux/bug.h:5,
> 			 from include/linux/mmdebug.h:5,
> 			 from include/linux/percpu.h:5,
> 			 from include/asm-generic/irq_regs.h:11,
> 			 from ./arch/arm/include/generated/asm/irq_regs.h:1,
> 			 from drivers/perf/arm_pmuv3.c:11:
> 	drivers/perf/arm_pmuv3.c: In function ‘armv8pmu_write_evtype’:
> 	include/linux/bits.h:34:29: error: left shift count >= width of type [-Werror=shift-count-overflow]
> 	   34 |         (((~UL(0)) - (UL(1) << (l)) + 1) & \
> 	      |                             ^~
> 	include/linux/bits.h:37:38: note: in expansion of macro ‘__GENMASK’
> 	   37 |         (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
> 	      |                                      ^~~~~~~~~
> 	include/linux/perf/arm_pmuv3.h:238:33: note: in expansion of macro ‘GENMASK’
> 	  238 | #define ARMV8_PMU_EVTYPE_TC     GENMASK(63, 61)
> 	      |                                 ^~~~~~~
> 	drivers/perf/arm_pmuv3.c:567:25: note: in expansion of macro ‘ARMV8_PMU_EVTYPE_TC’
> 	  567 |                 mask |= ARMV8_PMU_EVTYPE_TC | ARMV8_PMU_EVTYPE_TH;
> 	      |                         ^~~~~~~~~~~~~~~~~~~
> 	include/linux/bits.h:35:18: error: right shift count is negative [-Werror=shift-count-negative]
> 	   35 |          (~UL(0) >> (BITS_PER_LONG - 1 - (h))))
> 	      |                  ^~
> 	include/linux/bits.h:37:38: note: in expansion of macro ‘__GENMASK’
> 	   37 |         (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
> 	      |                                      ^~~~~~~~~
> 	include/linux/perf/arm_pmuv3.h:238:33: note: in expansion of macro ‘GENMASK’
> 	  238 | #define ARMV8_PMU_EVTYPE_TC     GENMASK(63, 61)
> 	      |                                 ^~~~~~~
> 	drivers/perf/arm_pmuv3.c:567:25: note: in expansion of macro ‘ARMV8_PMU_EVTYPE_TC’
> 	  567 |                 mask |= ARMV8_PMU_EVTYPE_TC | ARMV8_PMU_EVTYPE_TH;
> 	      |                         ^~~~~~~~~~~~~~~~~~~
> 	include/linux/bits.h:34:29: error: left shift count >= width of type [-Werror=shift-count-overflow]
> 	   34 |         (((~UL(0)) - (UL(1) << (l)) + 1) & \
> 	      |                             ^~
> 	include/linux/bits.h:37:38: note: in expansion of macro ‘__GENMASK’
> 	   37 |         (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
> 	      |                                      ^~~~~~~~~
> 	include/linux/perf/arm_pmuv3.h:237:33: note: in expansion of macro ‘GENMASK’
> 	  237 | #define ARMV8_PMU_EVTYPE_TH     GENMASK(43, 32)
> 	      |                                 ^~~~~~~
> 	drivers/perf/arm_pmuv3.c:567:47: note: in expansion of macro ‘ARMV8_PMU_EVTYPE_TH’
> 	  567 |                 mask |= ARMV8_PMU_EVTYPE_TC | ARMV8_PMU_EVTYPE_TH;
> 	      |                                               ^~~~~~~~~~~~~~~~~~~
> 	include/linux/bits.h:35:18: error: right shift count is negative [-Werror=shift-count-negative]
> 	   35 |          (~UL(0) >> (BITS_PER_LONG - 1 - (h))))
> 	      |                  ^~
> 	include/linux/bits.h:37:38: note: in expansion of macro ‘__GENMASK’
> 	   37 |         (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
> 	      |                                      ^~~~~~~~~
> 	include/linux/perf/arm_pmuv3.h:237:33: note: in expansion of macro ‘GENMASK’
> 	  237 | #define ARMV8_PMU_EVTYPE_TH     GENMASK(43, 32)
> 	      |                                 ^~~~~~~
> 	drivers/perf/arm_pmuv3.c:567:47: note: in expansion of macro ‘ARMV8_PMU_EVTYPE_TH’
> 	  567 |                 mask |= ARMV8_PMU_EVTYPE_TC | ARMV8_PMU_EVTYPE_TH;
> 	      |                                               ^~~~~~~~~~~~~~~~~~~
> 
> I guess that's easy to fix but I didn't look into that.
> 
> Best regards
> Uwe
> 

Thanks for the report. I see that the build is only broken with GCC and
is working with LLVM. I will look into a fix.

Worst case the if can be changed to an #ifdef

James