From 08a022ad3dfafc7e33d4529015e14bb75179cacc Mon Sep 17 00:00:00 2001 From: Jordan Niethe Date: Thu, 25 Feb 2021 14:21:06 +1100 Subject: [PATCH] powerpc/powernv/memtrace: Allow mmaping trace buffers 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 [mpe: make memtrace_mmap() static as noticed by lkp@intel.com] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210225032108.1458352-1-jniethe5@gmail.com --- arch/powerpc/platforms/powernv/memtrace.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/platforms/powernv/memtrace.c b/arch/powerpc/platforms/powernv/memtrace.c index 019669eb21d2..71c1262589fe 100644 --- a/arch/powerpc/platforms/powernv/memtrace.c +++ b/arch/powerpc/platforms/powernv/memtrace.c @@ -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); } +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 = { .llseek = default_llseek, .read = memtrace_read, .open = simple_open, + .mmap = memtrace_mmap, }; #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); 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("size", 0400, dir, &ent->size); } -- 2.34.1