[PATCH 1/3] powernv/memtrace: Allow mmaping trace buffers
flat view
STALE2023d
LANDED
From: Jordan Niethe <hidden>
Date: 2021-02-25 03:21:48
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
Landed in mainline as 08a022ad3dfa on 2021-04-08.
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 <redacted> --- 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 5fc9408bb0b3..8a1df39305e9 100644
--- a/arch/powerpc/platforms/powernv/memtrace.c
+++ b/arch/powerpc/platforms/powernv/memtrace.c@@ -45,10 +45,26 @@ static ssize_t memtrace_read(struct file *filp, char __user *ubuf, return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size); } +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, }; static void memtrace_clear_range(unsigned long start_pfn,
@@ -158,7 +174,7 @@ 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); }
--
2.25.1