lkml.org 
[lkml]   [2013]   [May]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
SubjectRe: [PATCH] powerpc, perf: Fix processing conditions for invalid BHRB entries
Date
Anshuman Khandual <khandual@linux.vnet.ibm.com> wrote:

> Fixing some conditions during BHRB entry processing.

I think we can simplify this a lot more... something like the below.

Also, this marks the "to" address as all 1s, which is better poison
value since it's possible to branch to/from 0x0.

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index c627843..d410d65 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -1463,65 +1463,45 @@ void power_pmu_bhrb_read(struct cpu_hw_events *cpuhw)
{
u64 val;
u64 addr;
- int r_index, u_index, target, pred;
+ int r_index, u_index, pred;

r_index = 0;
u_index = 0;
while (r_index < ppmu->bhrb_nr) {
/* Assembly read function */
- val = read_bhrb(r_index);
+ val = read_bhrb(r_index++);

/* Terminal marker: End of valid BHRB entries */
- if (val == 0) {
+ if (!val) {
break;
} else {
/* BHRB field break up */
addr = val & BHRB_EA;
pred = val & BHRB_PREDICTION;
- target = val & BHRB_TARGET;

- /* Probable Missed entry: Not applicable for POWER8 */
- if ((addr == 0) && (target == 0) && (pred == 1)) {
- r_index++;
+ if (!addr)
+ /* invalid entry */
continue;
- }
-
- /* Real Missed entry: Power8 based missed entry */
- if ((addr == 0) && (target == 1) && (pred == 1)) {
- r_index++;
- continue;
- }

- /* Reserved condition: Not a valid entry */
- if ((addr == 0) && (target == 1) && (pred == 0)) {
- r_index++;
- continue;
- }
-
- /* Is a target address */
if (val & BHRB_TARGET) {
/* First address cannot be a target address */
- if (r_index == 0) {
- r_index++;
+ if (r_index == 0)
continue;
- }

/* Update target address for the previous entry */
cpuhw->bhrb_entries[u_index - 1].to = addr;
cpuhw->bhrb_entries[u_index - 1].mispred = pred;
cpuhw->bhrb_entries[u_index - 1].predicted = ~pred;
-
- /* Dont increment u_index */
- r_index++;
} else {
/* Update address, flags for current entry */
cpuhw->bhrb_entries[u_index].from = addr;
+ cpuhw->bhrb_entries[u_index].to =
+ 0xffffffffffffffff;
cpuhw->bhrb_entries[u_index].mispred = pred;
cpuhw->bhrb_entries[u_index].predicted = ~pred;

/* Successfully popullated one entry */
u_index++;
- r_index++;
}
}
}

\
 
 \ /
  Last update: 2013-05-06 13:42    [W:0.480 / U:0.340 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site