Re: [PATCH V2 1/3] perf tools: Add fallback functions for cases where cpumode is insufficient

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Nov 06, 2018 at 11:07:10PM +0200, Adrian Hunter escreveu:
> For branch stacks or branch samples, the sample cpumode might not be
> correct because it applies only to the sample 'ip' and not necessary to
> 'addr' or branch stack addresses. Add fallback functions that can be used
> to deal with those cases

I've split this into two, and the first is causing this:

root@quaco ~]# perf top
perf: Segmentation fault
-------- backtrace --------
perf[0x59baca]
/lib64/libc.so.6(+0x385bf)[0x7fa2775dc5bf]
perf(perf_env__arch+0x34)[0x4b4514]
perf(perf_env__single_address_space+0x1b)[0x57944b]
perf(perf_session__new+0x17c)[0x4fdb3c]
perf(cmd_top+0x162c)[0x45109c]
perf[0x4a621e]
perf(main+0x61c)[0x42cbfc]
/lib64/libc.so.6(__libc_start_main+0xf2)[0x7fa2775c8412]
perf(_start+0x2d)[0x42ce2d]
[root@quaco ~]#

Its the case where the env info comes from the running machine, via
uname(), I'm working on a fix.

- Arnaldo
 
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> Cc: stable@vger.kernel.org # 4.19
> ---
>  tools/perf/arch/common.c  | 10 ++++++++++
>  tools/perf/arch/common.h  |  1 +
>  tools/perf/util/event.c   | 27 +++++++++++++++++++++++++++
>  tools/perf/util/machine.c | 27 +++++++++++++++++++++++++++
>  tools/perf/util/machine.h |  3 +++
>  tools/perf/util/session.c |  4 ++++
>  tools/perf/util/thread.h  |  4 ++++
>  7 files changed, 76 insertions(+)
> 
> diff --git a/tools/perf/arch/common.c b/tools/perf/arch/common.c
> index 82657c01a3b8..5f69fd0b745a 100644
> --- a/tools/perf/arch/common.c
> +++ b/tools/perf/arch/common.c
> @@ -200,3 +200,13 @@ int perf_env__lookup_objdump(struct perf_env *env, const char **path)
>  
>  	return perf_env__lookup_binutils_path(env, "objdump", path);
>  }
> +
> +/*
> + * Some architectures have a single address space for kernel and user addresses,
> + * which makes it possible to determine if an address is in kernel space or user
> + * space.
> + */
> +bool perf_env__single_address_space(struct perf_env *env)
> +{
> +	return strcmp(perf_env__arch(env), "sparc");
> +}
> diff --git a/tools/perf/arch/common.h b/tools/perf/arch/common.h
> index 2167001b18c5..c298a446d1f6 100644
> --- a/tools/perf/arch/common.h
> +++ b/tools/perf/arch/common.h
> @@ -5,5 +5,6 @@
>  #include "../util/env.h"
>  
>  int perf_env__lookup_objdump(struct perf_env *env, const char **path);
> +bool perf_env__single_address_space(struct perf_env *env);
>  
>  #endif /* ARCH_PERF_COMMON_H */
> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> index e9c108a6b1c3..9431b20c1337 100644
> --- a/tools/perf/util/event.c
> +++ b/tools/perf/util/event.c
> @@ -1577,6 +1577,24 @@ struct map *thread__find_map(struct thread *thread, u8 cpumode, u64 addr,
>  	return al->map;
>  }
>  
> +/*
> + * For branch stacks or branch samples, the sample cpumode might not be correct
> + * because it applies only to the sample 'ip' and not necessary to 'addr' or
> + * branch stack addresses. If possible, use a fallback to deal with those cases.
> + */
> +struct map *thread__find_map_fb(struct thread *thread, u8 cpumode, u64 addr,
> +				struct addr_location *al)
> +{
> +	struct map *map = thread__find_map(thread, cpumode, addr, al);
> +	struct machine *machine = thread->mg->machine;
> +	u8 addr_cpumode = machine__addr_cpumode(machine, cpumode, addr);
> +
> +	if (map || addr_cpumode == cpumode)
> +		return map;
> +
> +	return thread__find_map(thread, addr_cpumode, addr, al);
> +}
> +
>  struct symbol *thread__find_symbol(struct thread *thread, u8 cpumode,
>  				   u64 addr, struct addr_location *al)
>  {
> @@ -1586,6 +1604,15 @@ struct symbol *thread__find_symbol(struct thread *thread, u8 cpumode,
>  	return al->sym;
>  }
>  
> +struct symbol *thread__find_symbol_fb(struct thread *thread, u8 cpumode,
> +				      u64 addr, struct addr_location *al)
> +{
> +	al->sym = NULL;
> +	if (thread__find_map_fb(thread, cpumode, addr, al))
> +		al->sym = map__find_symbol(al->map, al->addr);
> +	return al->sym;
> +}
> +
>  /*
>   * Callers need to drop the reference to al->thread, obtained in
>   * machine__findnew_thread()
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 8f36ce813bc5..9397e3f2444d 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -2592,6 +2592,33 @@ int machine__get_kernel_start(struct machine *machine)
>  	return err;
>  }
>  
> +u8 machine__addr_cpumode(struct machine *machine, u8 cpumode, u64 addr)
> +{
> +	u8 addr_cpumode = cpumode;
> +	bool kernel_ip;
> +
> +	if (!machine->single_address_space)
> +		goto out;
> +
> +	kernel_ip = machine__kernel_ip(machine, addr);
> +	switch (cpumode) {
> +	case PERF_RECORD_MISC_KERNEL:
> +	case PERF_RECORD_MISC_USER:
> +		addr_cpumode = kernel_ip ? PERF_RECORD_MISC_KERNEL :
> +					   PERF_RECORD_MISC_USER;
> +		break;
> +	case PERF_RECORD_MISC_GUEST_KERNEL:
> +	case PERF_RECORD_MISC_GUEST_USER:
> +		addr_cpumode = kernel_ip ? PERF_RECORD_MISC_GUEST_KERNEL :
> +					   PERF_RECORD_MISC_GUEST_USER;
> +		break;
> +	default:
> +		break;
> +	}
> +out:
> +	return addr_cpumode;
> +}
> +
>  struct dso *machine__findnew_dso(struct machine *machine, const char *filename)
>  {
>  	return dsos__findnew(&machine->dsos, filename);
> diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
> index d856b85862e2..ebde3ea70225 100644
> --- a/tools/perf/util/machine.h
> +++ b/tools/perf/util/machine.h
> @@ -42,6 +42,7 @@ struct machine {
>  	u16		  id_hdr_size;
>  	bool		  comm_exec;
>  	bool		  kptr_restrict_warned;
> +	bool		  single_address_space;
>  	char		  *root_dir;
>  	char		  *mmap_name;
>  	struct threads    threads[THREADS__TABLE_SIZE];
> @@ -99,6 +100,8 @@ static inline bool machine__kernel_ip(struct machine *machine, u64 ip)
>  	return ip >= kernel_start;
>  }
>  
> +u8 machine__addr_cpumode(struct machine *machine, u8 cpumode, u64 addr);
> +
>  struct thread *machine__find_thread(struct machine *machine, pid_t pid,
>  				    pid_t tid);
>  struct comm *machine__thread_exec_comm(struct machine *machine,
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 7d2c8ce6cfad..f8eab197f35c 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -24,6 +24,7 @@
>  #include "thread.h"
>  #include "thread-stack.h"
>  #include "stat.h"
> +#include "arch/common.h"
>  
>  static int perf_session__deliver_event(struct perf_session *session,
>  				       union perf_event *event,
> @@ -150,6 +151,9 @@ struct perf_session *perf_session__new(struct perf_data *data,
>  		session->machines.host.env = &perf_env;
>  	}
>  
> +	session->machines.host.single_address_space =
> +		perf_env__single_address_space(session->machines.host.env);
> +
>  	if (!data || perf_data__is_write(data)) {
>  		/*
>  		 * In O_RDONLY mode this will be performed when reading the
> diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
> index 30e2b4c165fe..5920c3bb8ffe 100644
> --- a/tools/perf/util/thread.h
> +++ b/tools/perf/util/thread.h
> @@ -96,9 +96,13 @@ struct thread *thread__main_thread(struct machine *machine, struct thread *threa
>  
>  struct map *thread__find_map(struct thread *thread, u8 cpumode, u64 addr,
>  			     struct addr_location *al);
> +struct map *thread__find_map_fb(struct thread *thread, u8 cpumode, u64 addr,
> +				struct addr_location *al);
>  
>  struct symbol *thread__find_symbol(struct thread *thread, u8 cpumode,
>  				   u64 addr, struct addr_location *al);
> +struct symbol *thread__find_symbol_fb(struct thread *thread, u8 cpumode,
> +				      u64 addr, struct addr_location *al);
>  
>  void thread__find_cpumode_addr_location(struct thread *thread, u64 addr,
>  					struct addr_location *al);
> -- 
> 2.17.1

-- 

- Arnaldo