Re: [PATCH V12 05/10] arm64/perf: Add branch stack support in ARMV8 PMU

[Anshuman Khandual]

On 6/16/23 14:51, Catalin Marinas wrote:
> On Fri, Jun 16, 2023 at 06:57:52AM +0530, Anshuman Khandual wrote:
>> On 6/16/23 05:12, kernel test robot wrote:
>>> kernel test robot noticed the following build errors:
>>>
>>> [auto build test ERROR on arm64/for-next/core]
>>> [also build test ERROR on tip/perf/core acme/perf/core linus/master v6.4-rc6 next-20230615]
>>> [If your patch is applied to the wrong git tree, kindly drop us a note.
>>> And when submitting patch, we suggest to use '--base' as documented in
>>> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>>>
>>> url:    https://github.com/intel-lab-lkp/linux/commits/Anshuman-Khandual/drivers-perf-arm_pmu-Add-new-sched_task-callback/20230615-223352
>>> base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
>>> patch link:    https://lore.kernel.org/r/20230615133239.442736-6-anshuman.khandual%40arm.com
>>> patch subject: [PATCH V12 05/10] arm64/perf: Add branch stack support in ARMV8 PMU
>>> config: arm-randconfig-r004-20230615 (https://download.01.org/0day-ci/archive/20230616/202306160706.Uei5XDoi-lkp@xxxxxxxxx/config)
>>> compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
>>> reproduce (this is a W=1 build):
>>>         mkdir -p ~/bin
>>>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>>>         chmod +x ~/bin/make.cross
>>>         # install arm cross compiling tool for clang build
>>>         # apt-get install binutils-arm-linux-gnueabi
>>>         git remote add arm64 https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
>>>         git fetch arm64 for-next/core
>>>         git checkout arm64/for-next/core
>>>         b4 shazam https://lore.kernel.org/r/20230615133239.442736-6-anshuman.khandual@xxxxxxx
>>>         # save the config file
>>>         mkdir build_dir && cp config build_dir/.config
>>>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang ~/bin/make.cross W=1 O=build_dir ARCH=arm olddefconfig
>>>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang ~/bin/make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash drivers/perf/
>>
>> I am unable to reproduce this on mainline 6.4-rc6 via default cross compiler
>> on a W=1 build. Looking at all other problems reported on the file, it seems
>> something is not right here. Reported build problems around these callbacks,
>> i.e armv8pmu_branch_XXXX() do not make sense as they are available via config
>> CONFIG_PERF_EVENTS which is also enabled along with CONFIG_ARM_PMUV3 in this
>> test config.
> 
> Have you tried applying this series on top of the arm64 for-next/core
> branch? That's what the robot it testing (in the absence of a --base
> option when generating the patches).

Right, it turned out to be a build problem on arm (32 bit) platform instead.
After arm_pmuv3.c moved into common ./drivers/perf from ./arch/arm64/kernel/,
it can no longer access arch/arm64/include/asm/perf_event.h defined functions
without breaking arm (32) bit. The following code block needs to be moved out
from arch/arm64/include/asm/perf_event.h into include/linux/perf/arm_pmuv3.h
(which is preferred as all call sites are inside drivers/perf/arm_pmuv3.c) or
may be arm_pmu.h (which is one step higher in the abstraction).

struct pmu_hw_events;
struct arm_pmu;
struct perf_event;

#ifdef CONFIG_PERF_EVENTS
static inline bool has_branch_stack(struct perf_event *event);

#ifdef CONFIG_ARM64_BRBE
void armv8pmu_branch_read(struct pmu_hw_events *cpuc, struct perf_event *event);
bool armv8pmu_branch_attr_valid(struct perf_event *event);
void armv8pmu_branch_enable(struct perf_event *event);
void armv8pmu_branch_disable(struct perf_event *event);
void armv8pmu_branch_probe(struct arm_pmu *arm_pmu);
void armv8pmu_branch_reset(void);
int armv8pmu_task_ctx_cache_alloc(struct arm_pmu *arm_pmu);
void armv8pmu_task_ctx_cache_free(struct arm_pmu *arm_pmu);
void armv8pmu_branch_save(struct arm_pmu *arm_pmu, void *ctx);
#else
static inline void armv8pmu_branch_read(struct pmu_hw_events *cpuc, struct perf_event *event)
{
        WARN_ON_ONCE(!has_branch_stack(event));
}

static inline bool armv8pmu_branch_attr_valid(struct perf_event *event)
{
        WARN_ON_ONCE(!has_branch_stack(event));
        return false;
}

static inline void armv8pmu_branch_enable(struct perf_event *event)
{
        WARN_ON_ONCE(!has_branch_stack(event));
}

static inline void armv8pmu_branch_disable(struct perf_event *event)
{
        WARN_ON_ONCE(!has_branch_stack(event));
}

static inline void armv8pmu_branch_probe(struct arm_pmu *arm_pmu) { }
static inline void armv8pmu_branch_reset(void) { }
static inline int armv8pmu_task_ctx_cache_alloc(struct arm_pmu *arm_pmu) { return 0; }
static inline void armv8pmu_task_ctx_cache_free(struct arm_pmu *arm_pmu) { }
static inline void armv8pmu_branch_save(struct arm_pmu *arm_pmu, void *ctx) { }
#endif
#endif