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perf,mm: Handle non-page-table-aligned hugetlbfs

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A limited nunmber of architectures support hugetlbfs sizes that do not
align with the page-tables (ARM64, Power, Sparc64). Add support for
this to the generic perf_get_page_size() implementation, and also
allow an architecture to override this implementation.

This latter is only needed when it uses non-page-table aligned huge
pages in its kernel map.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
This commit is contained in:
Peter Zijlstra 2020-10-09 11:09:27 +02:00
parent 995f088efe
commit 51b646b2d9
2 changed files with 37 additions and 6 deletions
include/linux
perf_event.h
kernel/events
core.c

4
include/linux/perf_event.h
View File

@ -1590,4 +1590,8 @@ extern void __weak arch_perf_update_userpage(struct perf_event *event,
struct perf_event_mmap_page *userpg, struct perf_event_mmap_page *userpg,
u64 now); u64 now);
#ifdef CONFIG_MMU
extern __weak u64 arch_perf_get_page_size(struct mm_struct *mm, unsigned long addr);
#endif
#endif /* _LINUX_PERF_EVENT_H */ #endif /* _LINUX_PERF_EVENT_H */

39
kernel/events/core.c
View File

@ -7011,10 +7011,18 @@ static u64 perf_virt_to_phys(u64 virt)
#ifdef CONFIG_MMU #ifdef CONFIG_MMU
/* /*
* Return the MMU page size of a given virtual address * Return the MMU page size of a given virtual address.
*
* This generic implementation handles page-table aligned huge pages, as well
* as non-page-table aligned hugetlbfs compound pages.
*
* If an architecture supports and uses non-page-table aligned pages in their
* kernel mapping it will need to provide it's own implementation of this
* function.
*/ */
static u64 __perf_get_page_size(struct mm_struct *mm, unsigned long addr) __weak u64 arch_perf_get_page_size(struct mm_struct *mm, unsigned long addr)
{ {
struct page *page;
pgd_t *pgd; pgd_t *pgd;
p4d_t *p4d; p4d_t *p4d;
pud_t *pud; pud_t *pud;
@ -7036,15 +7044,27 @@ static u64 __perf_get_page_size(struct mm_struct *mm, unsigned long addr)
if (!pud_present(*pud)) if (!pud_present(*pud))
return 0; return 0;
if (pud_leaf(*pud)) if (pud_leaf(*pud)) {
#ifdef pud_page
page = pud_page(*pud);
if (PageHuge(page))
return page_size(compound_head(page));
#endif
return 1ULL << PUD_SHIFT; return 1ULL << PUD_SHIFT;
}
pmd = pmd_offset(pud, addr); pmd = pmd_offset(pud, addr);
if (!pmd_present(*pmd)) if (!pmd_present(*pmd))
return 0; return 0;
if (pmd_leaf(*pmd)) if (pmd_leaf(*pmd)) {
#ifdef pmd_page
page = pmd_page(*pmd);
if (PageHuge(page))
return page_size(compound_head(page));
#endif
return 1ULL << PMD_SHIFT; return 1ULL << PMD_SHIFT;
}
pte = pte_offset_map(pmd, addr); pte = pte_offset_map(pmd, addr);
if (!pte_present(*pte)) { if (!pte_present(*pte)) {
@ -7052,13 +7072,20 @@ static u64 __perf_get_page_size(struct mm_struct *mm, unsigned long addr)
return 0; return 0;
} }
page = pte_page(*pte);
if (PageHuge(page)) {
u64 size = page_size(compound_head(page));
pte_unmap(pte);
return size;
}
pte_unmap(pte); pte_unmap(pte);
return PAGE_SIZE; return PAGE_SIZE;
} }
#else #else
static u64 __perf_get_page_size(struct mm_struct *mm, unsigned long addr) static u64 arch_perf_get_page_size(struct mm_struct *mm, unsigned long addr)
{ {
return 0; return 0;
} }
@ -7089,7 +7116,7 @@ static u64 perf_get_page_size(unsigned long addr)
mm = &init_mm; mm = &init_mm;
} }
size = __perf_get_page_size(mm, addr); size = arch_perf_get_page_size(mm, addr);
local_irq_restore(flags); local_irq_restore(flags);