Re: [PATCH 1/2] perf/x86: Disable non generic regs for software/probe events

[Liang, Kan]

On 5/25/2019 4:48 AM, Ingo Molnar wrote:

* kan.li...@linux.intel.com <kan.li...@linux.intel.com> wrote:

@@ -57,6 +57,11 @@ static unsigned int pt_regs_offset[PERF_REG_X86_MAX] = {
  #endif
  };
  
+u64 non_generic_regs_mask(void)
+{
+       return (~((1ULL << PERF_REG_X86_XMM0) - 1));
+}
+
  u64 perf_reg_value(struct pt_regs *regs, int idx)
  {
        struct x86_perf_regs *perf_regs;
diff --git a/include/linux/perf_regs.h b/include/linux/perf_regs.h
index 4767474..c1c3454 100644
--- a/include/linux/perf_regs.h
+++ b/include/linux/perf_regs.h
@@ -9,6 +9,8 @@ struct perf_regs {
        struct pt_regs  *regs;
  };
  
+u64 non_generic_regs_mask(void);

This is a *constant* value, why is it in a separate function, not an
inline?

Or rather, since it's obviously a constant, name it in such a way.
(PERF_REG_X86_NON_GENERIC_MASK or so. >
To the generic code define it as 0 if arch headers haven't overriden it.


I will name it PERF_REG_NON_GENERIC_MASK in generic code.

Perf tool also defined a similar macro. I think I will define 
PERF_REG_NON_GENERIC_MASK in X86 uapi header. So both kernel and user 
space can use it.

I will send out V2 to address all comments.

Thanks,
Kan

+u64 __weak non_generic_regs_mask(void)
+{
+       return 0;
+}
+
+static inline bool has_non_generic_regs(struct perf_event *event)
+{
+       u64 mask = non_generic_regs_mask();
+
+       return ((event->attr.sample_regs_user & mask) ||
+               (event->attr.sample_regs_intr & mask));

'return' is not a function ...

+       /* only support generic regs */
+       if (has_non_generic_regs(event))
+               return -EOPNOTSUPP;

In human readable comments please use complete sentences with no
unnecessary abbreviations, i.e. "Only support generic registers".

Thanks,

        Ingo