GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-07-22 23:04:43 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

mm: add functions to track page directory modifications

Browse source 
Patch series "mm: Get rid of vmalloc_sync_(un)mappings()", v3.

After the recent issue with vmalloc and tracing code[1] on x86 and a
long history of previous issues related to the vmalloc_sync_mappings()
interface, I thought the time has come to remove it.  Please see [2],
[3], and [4] for some other issues in the past.

The patches add tracking of page-table directory changes to the vmalloc
and ioremap code.  Depending on which page-table levels changes have
been made, a new per-arch function is called:
arch_sync_kernel_mappings().

On x86-64 with 4-level paging, this function will not be called more
than 64 times in a systems runtime (because vmalloc-space takes 64 PGD
entries which are only populated, but never cleared).

As a side effect this also allows to get rid of vmalloc faults on x86,
making it safe to touch vmalloc'ed memory in the page-fault handler.
Note that this potentially includes per-cpu memory.

This patch (of 7):

Add page-table allocation functions which will keep track of changed
directory entries.  They are needed for new PGD, P4D, PUD, and PMD
entries and will be used in vmalloc and ioremap code to decide whether
any changes in the kernel mappings need to be synchronized between
page-tables in the system.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Link: http://lkml.kernel.org/r/20200515140023.25469-1-joro@8bytes.org
Link: http://lkml.kernel.org/r/20200515140023.25469-2-joro@8bytes.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joerg Roedel 2020-06-01 21:52:18 -07:00 • committed by Linus Torvalds
parent b200f5b58c
commit d862613800
3 changed files with 72 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

46
include/linux/mm.h
View file

@ -2091,13 +2091,54 @@ static inline pud_t *pud_alloc(struct mm_struct *mm, p4d_t *p4d,
return (unlikely(p4d_none(*p4d)) && __pud_alloc(mm, p4d, address)) ?
NULL : pud_offset(p4d, address);
}
static inline p4d_t *p4d_alloc_track(struct mm_struct *mm, pgd_t *pgd,
unsigned long address,
pgtbl_mod_mask *mod_mask)
{
if (unlikely(pgd_none(*pgd))) {
if (__p4d_alloc(mm, pgd, address))
return NULL;
*mod_mask |= PGTBL_PGD_MODIFIED;
}
return p4d_offset(pgd, address);
}
#endif /* !__ARCH_HAS_5LEVEL_HACK */
static inline pud_t *pud_alloc_track(struct mm_struct *mm, p4d_t *p4d,
unsigned long address,
pgtbl_mod_mask *mod_mask)
{
if (unlikely(p4d_none(*p4d))) {
if (__pud_alloc(mm, p4d, address))
return NULL;
*mod_mask |= PGTBL_P4D_MODIFIED;
}
return pud_offset(p4d, address);
}
static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
{
return (unlikely(pud_none(*pud)) && __pmd_alloc(mm, pud, address))?
NULL: pmd_offset(pud, address);
}
static inline pmd_t *pmd_alloc_track(struct mm_struct *mm, pud_t *pud,
unsigned long address,
pgtbl_mod_mask *mod_mask)
{
if (unlikely(pud_none(*pud))) {
if (__pmd_alloc(mm, pud, address))
return NULL;
*mod_mask |= PGTBL_PUD_MODIFIED;
}
return pmd_offset(pud, address);
}
#endif /* CONFIG_MMU */
#if USE_SPLIT_PTE_PTLOCKS
@ -2213,6 +2254,11 @@ static inline void pgtable_pte_page_dtor(struct page *page)
((unlikely(pmd_none(*(pmd))) && __pte_alloc_kernel(pmd))? \
NULL: pte_offset_kernel(pmd, address))
#define pte_alloc_kernel_track(pmd, address, mask) \
((unlikely(pmd_none(*(pmd))) && \
(__pte_alloc_kernel(pmd) || ({*(mask)|=PGTBL_PMD_MODIFIED;0;})))?\
NULL: pte_offset_kernel(pmd, address))
#if USE_SPLIT_PMD_PTLOCKS
static struct page *pmd_to_page(pmd_t *pmd)