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SubjectRe: [PATCH 8/8][v4] powerpc/perf: Export Power7 memory hierarchy info to user space.
On 09/14/2013 06:19 AM, Sukadev Bhattiprolu wrote:
> +static void power7_get_mem_data_src(union perf_mem_data_src *dsrc,
> + struct pt_regs *regs)
> +{
> + u64 idx;
> + u64 mmcra = regs->dsisr;
> + u64 addr;
> + int ret;
> + unsigned int instr;
> +
> + if (mmcra & POWER7_MMCRA_DCACHE_MISS) {
> + idx = mmcra & POWER7_MMCRA_DCACHE_SRC_MASK;
> + idx >>= POWER7_MMCRA_DCACHE_SRC_SHIFT;
> +
> + dsrc->val |= dcache_src_map[idx];
> + return;
> + }
> +
> + instr = 0;
> + addr = perf_instruction_pointer(regs);
> +
> + if (is_kernel_addr(addr))
> + instr = *(unsigned int *)addr;
> + else {
> + pagefault_disable();
> + ret = __get_user_inatomic(instr, (unsigned int __user *)addr);
> + pagefault_enable();
> + if (ret)
> + instr = 0;
> + }
> + if (instr && instr_is_load_store(&instr))


Wondering if there is any possibility of getting positive values for
"(mmcra & POWER7_MMCRA_DCACHE_SRC_MASK) >> POWER7_MMCRA_DCACHE_SRC_SHIFT"
when the marked instruction did not have MMCRA[POWER7_MMCRA_DCACHE_MISS]
bit set. In that case we should actually compute dsrc->val as in the previous
case. I did couple of experiments on a P7 box, but was not able to find a
instance for a marked instruction whose MMCRA[POWER7_MMCRA_DCACHE_MISS] bit
not set and have a positive value POWER7_MMCRA_DCACHE_SRC field.



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