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author | 2020-01-31 15:18:21 +1000 | |
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committer | 2020-01-31 16:58:35 +1000 | |
commit | b45f1b3b585e195a7daead16d914e164310b1df6 (patch) | |
tree | 6559d233ad438a3ac7ca2f9092c671284a6a9512 /mm/memory.c | |
parent | Merge branch 'linux-5.6' of git://github.com/skeggsb/linux into drm-next (diff) | |
parent | mm, drm/ttm: Fix vm page protection handling (diff) | |
download | linux-b45f1b3b585e195a7daead16d914e164310b1df6.tar.gz linux-b45f1b3b585e195a7daead16d914e164310b1df6.tar.bz2 linux-b45f1b3b585e195a7daead16d914e164310b1df6.zip |
Merge branch 'ttm-prot-fix' of git://people.freedesktop.org/~thomash/linux into drm-next
A small fix for the long-standing ttm vm page protection hack.
Sent as a separate PR as it touches mm, has all acks in place.
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Thomas Hellström (VMware) <thellstrom@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200116102411.3056-1-thomas_os@shipmail.org
Diffstat (limited to 'mm/memory.c')
-rw-r--r-- | mm/memory.c | 44 |
1 files changed, 40 insertions, 4 deletions
diff --git a/mm/memory.c b/mm/memory.c index 45442d9a4f52..e24c7d22b117 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1664,6 +1664,9 @@ out_unlock: * vmf_insert_pfn_prot should only be used if using multiple VMAs is * impractical. * + * See vmf_insert_mixed_prot() for a discussion of the implication of using + * a value of @pgprot different from that of @vma->vm_page_prot. + * * Context: Process context. May allocate using %GFP_KERNEL. * Return: vm_fault_t value. */ @@ -1737,9 +1740,9 @@ static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn) } static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma, - unsigned long addr, pfn_t pfn, bool mkwrite) + unsigned long addr, pfn_t pfn, pgprot_t pgprot, + bool mkwrite) { - pgprot_t pgprot = vma->vm_page_prot; int err; BUG_ON(!vm_mixed_ok(vma, pfn)); @@ -1782,10 +1785,43 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma, return VM_FAULT_NOPAGE; } +/** + * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot + * @vma: user vma to map to + * @addr: target user address of this page + * @pfn: source kernel pfn + * @pgprot: pgprot flags for the inserted page + * + * This is exactly like vmf_insert_mixed(), except that it allows drivers to + * to override pgprot on a per-page basis. + * + * Typically this function should be used by drivers to set caching- and + * encryption bits different than those of @vma->vm_page_prot, because + * the caching- or encryption mode may not be known at mmap() time. + * This is ok as long as @vma->vm_page_prot is not used by the core vm + * to set caching and encryption bits for those vmas (except for COW pages). + * This is ensured by core vm only modifying these page table entries using + * functions that don't touch caching- or encryption bits, using pte_modify() + * if needed. (See for example mprotect()). + * Also when new page-table entries are created, this is only done using the + * fault() callback, and never using the value of vma->vm_page_prot, + * except for page-table entries that point to anonymous pages as the result + * of COW. + * + * Context: Process context. May allocate using %GFP_KERNEL. + * Return: vm_fault_t value. + */ +vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr, + pfn_t pfn, pgprot_t pgprot) +{ + return __vm_insert_mixed(vma, addr, pfn, pgprot, false); +} +EXPORT_SYMBOL(vmf_insert_mixed_prot); + vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr, pfn_t pfn) { - return __vm_insert_mixed(vma, addr, pfn, false); + return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false); } EXPORT_SYMBOL(vmf_insert_mixed); @@ -1797,7 +1833,7 @@ EXPORT_SYMBOL(vmf_insert_mixed); vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr, pfn_t pfn) { - return __vm_insert_mixed(vma, addr, pfn, true); + return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true); } EXPORT_SYMBOL(vmf_insert_mixed_mkwrite); |