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powerpc/powernv/memtrace: Allow mmaping trace buffers

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Let the memory removed from the linear mapping to be used for the trace
buffers be mmaped. This is a useful way of providing cache-inhibited
memory for the alignment_handler selftest.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
[mpe: make memtrace_mmap() static as noticed by lkp@intel.com]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210225032108.1458352-1-jniethe5@gmail.com
This commit is contained in:
Jordan Niethe
2021-02-25 14:21:06 +11:00
committed by Michael Ellerman
parent acd4dfeb49
commit 08a022ad3d
1 changed files with 17 additions and 1 deletions
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18
arch/powerpc/platforms/powernv/memtrace.c
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@@ -46,10 +46,26 @@ static ssize_t memtrace_read(struct file *filp, char __user *ubuf,
return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size); return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size);
} }
static int memtrace_mmap(struct file *filp, struct vm_area_struct *vma)
{
struct memtrace_entry *ent = filp->private_data;
if (ent->size < vma->vm_end - vma->vm_start)
return -EINVAL;
if (vma->vm_pgoff << PAGE_SHIFT >= ent->size)
return -EINVAL;
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
return remap_pfn_range(vma, vma->vm_start, PHYS_PFN(ent->start) + vma->vm_pgoff,
vma->vm_end - vma->vm_start, vma->vm_page_prot);
}
static const struct file_operations memtrace_fops = { static const struct file_operations memtrace_fops = {
.llseek = default_llseek, .llseek = default_llseek,
.read = memtrace_read, .read = memtrace_read,
.open = simple_open, .open = simple_open,
.mmap = memtrace_mmap,
}; };
#define FLUSH_CHUNK_SIZE SZ_1G #define FLUSH_CHUNK_SIZE SZ_1G
@@ -187,7 +203,7 @@ static int memtrace_init_debugfs(void)
dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir); dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
ent->dir = dir; ent->dir = dir;
debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops); debugfs_create_file_unsafe("trace", 0600, dir, ent, &memtrace_fops);
debugfs_create_x64("start", 0400, dir, &ent->start); debugfs_create_x64("start", 0400, dir, &ent->start);
debugfs_create_x64("size", 0400, dir, &ent->size); debugfs_create_x64("size", 0400, dir, &ent->size);
} }