Em Tue, Aug 03, 2010 at 12:48:35PM +0100, Dave Martin escreveu:
Fix buggy-looking code which unnecessarily adjusts the file offset fields read from /proc/*/maps.
This may have gone unnoticed since the offset is usually 0 (and the logic in util/symbol.c may work incorrectly for other offset values).
I make assumptions about the intended design here. The cover note accompanying this patch contains a more detailed explanation.
Signed-off-by: Dave Martin dave.martin@linaro.org
Doing some investigation here...
4af8b35d (Anton Blanchard 2010-04-03 164) pbf += 3; 4af8b35d (Anton Blanchard 2010-04-03 165) n = hex2u64(pbf, &vm_pgoff); 4af8b35d (Anton Blanchard 2010-04-03 166) /* pgoff is in bytes, not pages */ 4af8b35d (Anton Blanchard 2010-04-03 167) if (n >= 0) 4af8b35d (Anton Blanchard 2010-04-03 168) ev.mmap.pgoff = vm_pgoff << getpagesize(); 4af8b35d (Anton Blanchard 2010-04-03 169) else 4af8b35d (Anton Blanchard 2010-04-03 170) ev.mmap.pgoff = 0;
commit 4af8b35db6634dd1e0d616de689582b6c93550af Author: Anton Blanchard anton@samba.org Date: Sat Apr 3 22:53:31 2010 +1100
perf symbols: Fill in pgoff in mmap synthesized events
When we synthesize mmap events we need to fill in the pgoff field.
I wasn't able to test this completely since I couldn't find an executable region with a non 0 offset. We will see it when we start doing data profiling.
------------------------
Yeah, not reassuring comment, looking at fs/proc/task_mmu.c we see:
static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma) { struct mm_struct *mm = vma->vm_mm; struct file *file = vma->vm_file; int flags = vma->vm_flags; unsigned long ino = 0; unsigned long long pgoff = 0; dev_t dev = 0; int len;
if (file) { struct inode *inode = vma->vm_file->f_path.dentry->d_inode; dev = inode->i_sb->s_dev; ino = inode->i_ino; pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT; }
seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n", vma->vm_start, vma->vm_end, flags & VM_READ ? 'r' : '-', flags & VM_WRITE ? 'w' : '-', flags & VM_EXEC ? 'x' : '-', flags & VM_MAYSHARE ? 's' : 'p', pgoff, MAJOR(dev), MINOR(dev), ino, &len);
----------------------------------------------------------------------------
So yes, we're double shifting that, your patch is correct, applying it.
tools/perf/util/event.c | 8 +------- 1 files changed, 1 insertions(+), 7 deletions(-)
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c index 6b0db55..db8a1d4 100644 --- a/tools/perf/util/event.c +++ b/tools/perf/util/event.c @@ -151,7 +151,6 @@ static int event__synthesize_mmap_events(pid_t pid, pid_t tgid, continue; pbf += n + 3; if (*pbf == 'x') { /* vm_exec */
u64 vm_pgoff; char *execname = strchr(bf, '/');/* Catch VDSO */ @@ -162,12 +161,7 @@ static int event__synthesize_mmap_events(pid_t pid, pid_t tgid, continue; pbf += 3;
n = hex2u64(pbf, &vm_pgoff);/* pgoff is in bytes, not pages */if (n >= 0)ev.mmap.pgoff = vm_pgoff << getpagesize();elseev.mmap.pgoff = 0;
n = hex2u64(pbf, &ev.mmap.pgoff);size = strlen(execname); execname[size - 1] = '\0'; /* Remove \n */ -- 1.7.0.4