Re: [PATCH] riscv: Improve kasan population by using hugepages when possible
Le 2/2/21 à 3:50 AM, Alex Ghiti a écrit :
Hi,
Le 2/1/21 à 3:00 AM, Alexandre Ghiti a écrit :
Kasan function that populates the shadow regions used to allocate them
page by page and did not take advantage of hugepages, so fix this by
trying to allocate hugepages of 1GB and fallback to 2MB hugepages or 4K
pages in case it fails.
This reduces the page table memory consumption and improves TLB usage,
as shown below:
Before this patch:
---[ Kasan shadow start ]---
0xffc0-0xffc4 0x818ef000 16G
PTE . A . . . . R V
0xffc4-0xffc447fc 0x0002b7f4f000 1179392K
PTE D A . . . W R V
0xffc48000-0xffc8 0x818ef000 14G
PTE . A . . . . R V
---[ Kasan shadow end ]---
After this patch:
---[ Kasan shadow start ]---
0xffc0-0xffc4 0x818ef000 16G
PTE . A . . . . R V
0xffc4-0xffc44000 0x00024000 1G
PGD D A . . . W R V
0xffc44000-0xffc447e0 0x0002b7e0 126M
PMD D A . . . W R V
0xffc447e0-0xffc447fc 0x0002b818f000 1792K
PTE D A . . . W R V
0xffc48000-0xffc8 0x818ef000 14G
PTE . A . . . . R V
---[ Kasan shadow end ]---
Signed-off-by: Alexandre Ghiti
---
arch/riscv/mm/kasan_init.c | 101 +++--
1 file changed, 73 insertions(+), 28 deletions(-)
diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index a8a2ffd9114a..8f11b73018b1 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -47,37 +47,82 @@ asmlinkage void __init kasan_early_init(void)
local_flush_tlb_all();
}
-static void __init populate(void *start, void *end)
+static void kasan_populate_pte(pmd_t *pmd, unsigned long vaddr,
unsigned long end)
+{
+ phys_addr_t phys_addr;
+ pte_t *ptep = memblock_alloc(PTRS_PER_PTE * sizeof(pte_t),
PAGE_SIZE);
+
+ do {
+ phys_addr = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
+ set_pte(ptep, pfn_pte(PFN_DOWN(phys_addr), PAGE_KERNEL));
+ } while (ptep++, vaddr += PAGE_SIZE, vaddr != end);
+
+ set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa(ptep)), PAGE_TABLE));
+}
+
+static void kasan_populate_pmd(pgd_t *pgd, unsigned long vaddr,
unsigned long end)
+{
+ phys_addr_t phys_addr;
+ pmd_t *pmdp = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t),
PAGE_SIZE);
+ unsigned long next;
+
+ do {
+ next = pmd_addr_end(vaddr, end);
+
+ if (IS_ALIGNED(vaddr, PMD_SIZE) && (next - vaddr) >= PMD_SIZE) {
+ phys_addr = memblock_phys_alloc(PMD_SIZE, PMD_SIZE);
+ if (phys_addr) {
+ set_pmd(pmdp, pfn_pmd(PFN_DOWN(phys_addr),
PAGE_KERNEL));
+ continue;
+ }
+ }
+
+ kasan_populate_pte(pmdp, vaddr, end);
+ } while (pmdp++, vaddr = next, vaddr != end);
+
+ /*
+ * Wait for the whole PGD to be populated before setting the PGD in
+ * the page table, otherwise, if we did set the PGD before
populating
+ * it entirely, memblock could allocate a page at a physical address
+ * where KASAN is not populated yet and then we'd get a page fault.
+ */
+ set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(pmdp)), PAGE_TABLE));
In case the PMD was filled entirely, PFN_DOWN(__pa(pmdp)) will point to
the next physical page, which is wrong. The same problem happens on the
other levels too.
I'll fix that in a v2 later today.
Alex
+}
+
+static void kasan_populate_pgd(unsigned long vaddr, unsigned long end)
+{
+ phys_addr_t phys_addr;
+ pgd_t *pgdp = pgd_offset_k(vaddr);
+ unsigned long next;
+
+ do {
+ next = pgd_addr_end(vaddr, end);
+
+ if (IS_ALIGNED(vaddr, PGDIR_SIZE) && (next - vaddr) >=
PGDIR_SIZE) {
+ phys_addr = memblock_phys_alloc(PGDIR_SIZE, PGDIR_SIZE);
+ if (phys_addr) {
+ set_pgd(pgdp, pfn_pgd(PFN_DOWN(phys_addr),
PAGE_KERNEL));
+ continue;
+ }
+ }
+
+ kasan_populate_pmd(pgdp, vaddr, end);
+ } while (pgdp++, vaddr = next, vaddr != end);
+}
+
+/*
+ * This function populates KASAN shadow region focusing on hugepages in
+ * order to minimize the page table cost and TLB usage too.
+ * Note that start must be PGDIR_SIZE-aligned in SV39 which amounts
to be
+ * 1G aligned (that represents a 8G alignment constraint on virtual
address
+ * ranges because of KASAN_SHADOW_SCALE_SHIFT).
+ */
+static void __init kasan_populate(void *start, void *end)
{
- unsigned long i, offset;
unsigned long vaddr = (unsigned long)start & PAGE_MASK;
unsigned long vend = PAGE_ALIGN((unsigned long)end);
- unsigned long n_pages = (vend - vaddr) / PAGE_SIZE;
- unsigned long n_ptes =
- ((n_pages + PTRS_PER_PTE) & -PTRS_PER_PTE) / PTRS_PER_PTE;
- unsigned long n_pmds =
- ((n_ptes + PTRS_PER_PMD) &
Re: [PATCH] riscv: Improve kasan population by using hugepages when possible
Hi,
Le 2/1/21 à 3:00 AM, Alexandre Ghiti a écrit :
Kasan function that populates the shadow regions used to allocate them
page by page and did not take advantage of hugepages, so fix this by
trying to allocate hugepages of 1GB and fallback to 2MB hugepages or 4K
pages in case it fails.
This reduces the page table memory consumption and improves TLB usage,
as shown below:
Before this patch:
---[ Kasan shadow start ]---
0xffc0-0xffc40x818ef00016G PTE
. A . . . . R V
0xffc4-0xffc447fc0x0002b7f4f000 1179392K PTE
D A . . . W R V
0xffc48000-0xffc80x818ef00014G PTE
. A . . . . R V
---[ Kasan shadow end ]---
After this patch:
---[ Kasan shadow start ]---
0xffc0-0xffc40x818ef00016G PTE
. A . . . . R V
0xffc4-0xffc440000x00024000 1G PGD
D A . . . W R V
0xffc44000-0xffc447e00x0002b7e0 126M PMD
D A . . . W R V
0xffc447e0-0xffc447fc0x0002b818f000 1792K PTE
D A . . . W R V
0xffc48000-0xffc80x818ef00014G PTE
. A . . . . R V
---[ Kasan shadow end ]---
Signed-off-by: Alexandre Ghiti
---
arch/riscv/mm/kasan_init.c | 101 +++--
1 file changed, 73 insertions(+), 28 deletions(-)
diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index a8a2ffd9114a..8f11b73018b1 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -47,37 +47,82 @@ asmlinkage void __init kasan_early_init(void)
local_flush_tlb_all();
}
-static void __init populate(void *start, void *end)
+static void kasan_populate_pte(pmd_t *pmd, unsigned long vaddr, unsigned long
end)
+{
+ phys_addr_t phys_addr;
+ pte_t *ptep = memblock_alloc(PTRS_PER_PTE * sizeof(pte_t), PAGE_SIZE);
+
+ do {
+ phys_addr = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
+ set_pte(ptep, pfn_pte(PFN_DOWN(phys_addr), PAGE_KERNEL));
+ } while (ptep++, vaddr += PAGE_SIZE, vaddr != end);
+
+ set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa(ptep)), PAGE_TABLE));
+}
+
+static void kasan_populate_pmd(pgd_t *pgd, unsigned long vaddr, unsigned long
end)
+{
+ phys_addr_t phys_addr;
+ pmd_t *pmdp = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
+ unsigned long next;
+
+ do {
+ next = pmd_addr_end(vaddr, end);
+
+ if (IS_ALIGNED(vaddr, PMD_SIZE) && (next - vaddr) >= PMD_SIZE) {
+ phys_addr = memblock_phys_alloc(PMD_SIZE, PMD_SIZE);
+ if (phys_addr) {
+ set_pmd(pmdp, pfn_pmd(PFN_DOWN(phys_addr),
PAGE_KERNEL));
+ continue;
+ }
+ }
+
+ kasan_populate_pte(pmdp, vaddr, end);
+ } while (pmdp++, vaddr = next, vaddr != end);
+
+ /*
+* Wait for the whole PGD to be populated before setting the PGD in
+* the page table, otherwise, if we did set the PGD before populating
+* it entirely, memblock could allocate a page at a physical address
+* where KASAN is not populated yet and then we'd get a page fault.
+*/
+ set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(pmdp)), PAGE_TABLE));
In case the PMD was filled entirely, PFN_DOWN(__pa(pmdp)) will point to
the next physical page, which is wrong. The same problem happens on the
other levels too.
I'll fix that in a v2 later today.
Alex
+}
+
+static void kasan_populate_pgd(unsigned long vaddr, unsigned long end)
+{
+ phys_addr_t phys_addr;
+ pgd_t *pgdp = pgd_offset_k(vaddr);
+ unsigned long next;
+
+ do {
+ next = pgd_addr_end(vaddr, end);
+
+ if (IS_ALIGNED(vaddr, PGDIR_SIZE) && (next - vaddr) >=
PGDIR_SIZE) {
+ phys_addr = memblock_phys_alloc(PGDIR_SIZE, PGDIR_SIZE);
+ if (phys_addr) {
+ set_pgd(pgdp, pfn_pgd(PFN_DOWN(phys_addr),
PAGE_KERNEL));
+ continue;
+ }
+ }
+
+ kasan_populate_pmd(pgdp, vaddr, end);
+ } while (pgdp++, vaddr = next, vaddr != end);
+}
+
+/*
+ * This function populates KASAN shadow region focusing on hugepages in
+ * order to minimize the page table cost and TLB usage too.
+ * Note that start must be PGDIR_SIZE-aligned in SV39 which amounts to be
+ * 1G aligned (that represents a 8G alignment constraint on virtual address
+ * ranges because of KASAN_SHADOW_SCALE_SHIFT).
+ */
+static void __init kasan_populate(void *start, void *end)
{
- unsigned long i, offset;
unsigned long vaddr = (unsigned long)start & PAGE_MASK;
unsigned long vend = PAGE_ALIGN((unsigned long)end);
-
[PATCH] riscv: Improve kasan population by using hugepages when possible
Kasan function that populates the shadow regions used to allocate them
page by page and did not take advantage of hugepages, so fix this by
trying to allocate hugepages of 1GB and fallback to 2MB hugepages or 4K
pages in case it fails.
This reduces the page table memory consumption and improves TLB usage,
as shown below:
Before this patch:
---[ Kasan shadow start ]---
0xffc0-0xffc40x818ef00016G PTE
. A . . . . R V
0xffc4-0xffc447fc0x0002b7f4f000 1179392K PTE
D A . . . W R V
0xffc48000-0xffc80x818ef00014G PTE
. A . . . . R V
---[ Kasan shadow end ]---
After this patch:
---[ Kasan shadow start ]---
0xffc0-0xffc40x818ef00016G PTE
. A . . . . R V
0xffc4-0xffc440000x00024000 1G PGD
D A . . . W R V
0xffc44000-0xffc447e00x0002b7e0 126M PMD
D A . . . W R V
0xffc447e0-0xffc447fc0x0002b818f000 1792K PTE
D A . . . W R V
0xffc48000-0xffc80x818ef00014G PTE
. A . . . . R V
---[ Kasan shadow end ]---
Signed-off-by: Alexandre Ghiti
---
arch/riscv/mm/kasan_init.c | 101 +++--
1 file changed, 73 insertions(+), 28 deletions(-)
diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index a8a2ffd9114a..8f11b73018b1 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -47,37 +47,82 @@ asmlinkage void __init kasan_early_init(void)
local_flush_tlb_all();
}
-static void __init populate(void *start, void *end)
+static void kasan_populate_pte(pmd_t *pmd, unsigned long vaddr, unsigned long
end)
+{
+ phys_addr_t phys_addr;
+ pte_t *ptep = memblock_alloc(PTRS_PER_PTE * sizeof(pte_t), PAGE_SIZE);
+
+ do {
+ phys_addr = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
+ set_pte(ptep, pfn_pte(PFN_DOWN(phys_addr), PAGE_KERNEL));
+ } while (ptep++, vaddr += PAGE_SIZE, vaddr != end);
+
+ set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa(ptep)), PAGE_TABLE));
+}
+
+static void kasan_populate_pmd(pgd_t *pgd, unsigned long vaddr, unsigned long
end)
+{
+ phys_addr_t phys_addr;
+ pmd_t *pmdp = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
+ unsigned long next;
+
+ do {
+ next = pmd_addr_end(vaddr, end);
+
+ if (IS_ALIGNED(vaddr, PMD_SIZE) && (next - vaddr) >= PMD_SIZE) {
+ phys_addr = memblock_phys_alloc(PMD_SIZE, PMD_SIZE);
+ if (phys_addr) {
+ set_pmd(pmdp, pfn_pmd(PFN_DOWN(phys_addr),
PAGE_KERNEL));
+ continue;
+ }
+ }
+
+ kasan_populate_pte(pmdp, vaddr, end);
+ } while (pmdp++, vaddr = next, vaddr != end);
+
+ /*
+* Wait for the whole PGD to be populated before setting the PGD in
+* the page table, otherwise, if we did set the PGD before populating
+* it entirely, memblock could allocate a page at a physical address
+* where KASAN is not populated yet and then we'd get a page fault.
+*/
+ set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(pmdp)), PAGE_TABLE));
+}
+
+static void kasan_populate_pgd(unsigned long vaddr, unsigned long end)
+{
+ phys_addr_t phys_addr;
+ pgd_t *pgdp = pgd_offset_k(vaddr);
+ unsigned long next;
+
+ do {
+ next = pgd_addr_end(vaddr, end);
+
+ if (IS_ALIGNED(vaddr, PGDIR_SIZE) && (next - vaddr) >=
PGDIR_SIZE) {
+ phys_addr = memblock_phys_alloc(PGDIR_SIZE, PGDIR_SIZE);
+ if (phys_addr) {
+ set_pgd(pgdp, pfn_pgd(PFN_DOWN(phys_addr),
PAGE_KERNEL));
+ continue;
+ }
+ }
+
+ kasan_populate_pmd(pgdp, vaddr, end);
+ } while (pgdp++, vaddr = next, vaddr != end);
+}
+
+/*
+ * This function populates KASAN shadow region focusing on hugepages in
+ * order to minimize the page table cost and TLB usage too.
+ * Note that start must be PGDIR_SIZE-aligned in SV39 which amounts to be
+ * 1G aligned (that represents a 8G alignment constraint on virtual address
+ * ranges because of KASAN_SHADOW_SCALE_SHIFT).
+ */
+static void __init kasan_populate(void *start, void *end)
{
- unsigned long i, offset;
unsigned long vaddr = (unsigned long)start & PAGE_MASK;
unsigned long vend = PAGE_ALIGN((unsigned long)end);
- unsigned long n_pages = (vend - vaddr) / PAGE_SIZE;
- unsigned long n_ptes =
- ((n_pages + PTRS_PER_PTE) & -PTRS_PER_PTE) / PTRS_PER_PTE;
- unsigned long n_pmds =
- ((n_ptes + PTRS_PER_PMD) & -PTRS_PER_PMD) / PTRS_PER_PMD;
-
- pte_t *pte =
