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ANDROID: dma-buf: Add vendorhook to allow mmaping more memory than a DMA-BUF holds

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Add vendorhook to allow mmaping more memory than a DMA-BUF holds. The
implementor of the vmap callback for the DMA-BUF is responsible for
ensuring that all pages are backed by memory. The hook takes as input
a DMA-BUF to allow the VMA bounds check to be done on a case-by-case
basis for DMA-BUFs.

Note that if the override is allowed to go through for a given
DMA-BUF, then it can be the case that the size of this "fully" mmaped
DMA-BUF is reported incorrectly when looking at /proc/pid/maps for the
owning process.

[revert when android14-6.<next> gets created]
Bug: 234753494
Change-Id: Iba8cc8adfd2290e4dc7ef04fce5d6a80ac92e0b3
Signed-off-by: Chris Goldsworthy <quic_cgoldswo@quicinc.com>
This commit is contained in:
Chris Goldsworthy 2022-07-27 16:58:09 -07:00 committed by Chris Goldsworthy
parent ff712ce9e0
commit 8a0c17585f
3 changed files with 29 additions and 2 deletions
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2
drivers/android/vendor_hooks.c
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@ -12,6 +12,7 @@
#include <trace/hooks/sched.h>
#include <trace/hooks/fpsimd.h>
#include <trace/hooks/binder.h>
#include <trace/hooks/dma_buf.h>
#include <trace/hooks/cpuidle.h>
#include <trace/hooks/mpam.h>
#include <trace/hooks/wqlockup.h>
@ -107,6 +108,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_ufs_send_uic_command);
EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_ufs_send_tm_command);
EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_ufs_check_int_errors);
EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_cgroup_attach);
EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_ignore_dmabuf_vmap_bounds);
EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_iommu_setup_dma_ops);
EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_iommu_iovad_alloc_iova);
EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_iommu_iovad_free_iova);

8
drivers/dma-buf/dma-buf.c
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@ -25,6 +25,7 @@
#include <linux/mm.h>
#include <linux/mount.h>
#include <linux/pseudo_fs.h>
#include <trace/hooks/dma_buf.h>
#include <uapi/linux/dma-buf.h>
#include <uapi/linux/magic.h>
@ -128,6 +129,7 @@ static struct file_system_type dma_buf_fs_type = {
static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
{
struct dma_buf *dmabuf;
bool ignore_bounds = false;
if (!is_dma_buf_file(file))
return -EINVAL;
@ -138,9 +140,11 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
if (!dmabuf->ops->mmap)
return -EINVAL;
trace_android_vh_ignore_dmabuf_vmap_bounds(dmabuf, &ignore_bounds);
/* check for overflowing the buffer's size */
if (vma->vm_pgoff + vma_pages(vma) >
dmabuf->size >> PAGE_SHIFT)
if ((vma->vm_pgoff + vma_pages(vma) >
dmabuf->size >> PAGE_SHIFT) && !ignore_bounds)
return -EINVAL;
return dmabuf->ops->mmap(dmabuf, vma);

21
include/trace/hooks/dma_buf.h Normal file
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@ -0,0 +1,21 @@
/* SPDX-License-Identifier: GPL-2.0 */
#undef TRACE_SYSTEM
#define TRACE_SYSTEM dma_buf
#define TRACE_INCLUDE_PATH trace/hooks
#if !defined(_TRACE_HOOK_DMA_BUF_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_HOOK_DMA_BUF_H
#include <linux/dma-buf.h>
#include <trace/hooks/vendor_hooks.h>
DECLARE_HOOK(android_vh_ignore_dmabuf_vmap_bounds,
TP_PROTO(struct dma_buf *dma_buf, bool *ignore_bounds),
TP_ARGS(dma_buf, ignore_bounds));
#endif /* _TRACE_HOOK_DMA_BUF_H */
/* This part must be outside protection */
#include <trace/define_trace.h>