[PATCH v4 0/6] RISC-V kasan rework

[PATCH v4 0/6] RISC-V kasan rework

[Alexandre Ghiti]

As described in patch 2, our current kasan implementation is intricate,
so I tried to simplify the implementation and mimic what arm64/x86 are
doing.

In addition it fixes UEFI bootflow with a kasan kernel and kasan inline
instrumentation: all kasan configurations were tested on a large ubuntu
kernel with success with KASAN_KUNIT_TEST and KASAN_MODULE_TEST.

inline ubuntu config + uefi:
 sv39: OK
 sv48: OK
 sv57: OK

outline ubuntu config + uefi:
 sv39: OK
 sv48: OK
 sv57: OK

Actually 1 test always fails with KASAN_KUNIT_TEST that I have to check:
# kasan_bitops_generic: EXPECTATION FAILED at mm/kasan/kasan__test.c:1020
KASAN failure expected in "set_bit(nr, addr)", but none occurrred

Note that Palmer recently proposed to remove COMMAND_LINE_SIZE from the
userspace abi
https://lore.kernel.org/lkml/20221211061358.28035-1-palmer@rivosinc.com/T/
so that we can finally increase the command line to fit all kasan kernel
parameters.

All of this should hopefully fix the syzkaller riscv build that has been
failing for a few months now, any test is appreciated and if I can help
in any way, please ask.

base-commit-tag: v6.2-rc6

v4:
- Fix build warning by declaring create_tmp_mapping as static, kernel
  test robot

v3:
- Add AB from Ard in patch 4, thanks
- Fix checkpatch issues in patch 1, thanks Conor

v2:
- Rebase on top of v6.2-rc3
- patch 4 is now way simpler than it used to be since Ard already moved
  the string functions into the efistub.

Alexandre Ghiti (6):
  riscv: Split early and final KASAN population functions
  riscv: Rework kasan population functions
  riscv: Move DTB_EARLY_BASE_VA to the kernel address space
  riscv: Fix EFI stub usage of KASAN instrumented strcmp function
  riscv: Fix ptdump when KASAN is enabled
  riscv: Unconditionnally select KASAN_VMALLOC if KASAN

 arch/riscv/Kconfig             |   1 +
 arch/riscv/kernel/image-vars.h |   2 -
 arch/riscv/mm/init.c           |   2 +-
 arch/riscv/mm/kasan_init.c     | 516 ++++++++++++++++++---------------
 arch/riscv/mm/ptdump.c         |  24 +-
 5 files changed, 298 insertions(+), 247 deletions(-)

-- 
2.37.2

[PATCH v4 1/6] riscv: Split early and final KASAN population functions

[Alexandre Ghiti]

This is a preliminary work that allows to make the code more
understandable.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 arch/riscv/mm/kasan_init.c | 185 +++++++++++++++++++++++--------------
 1 file changed, 116 insertions(+), 69 deletions(-)

diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index e1226709490f..2a48eba6bd08 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -95,23 +95,13 @@ static void __init kasan_populate_pmd(pud_t *pud, unsigned long vaddr, unsigned
 }
 
 static void __init kasan_populate_pud(pgd_t *pgd,
-				      unsigned long vaddr, unsigned long end,
-				      bool early)
+				      unsigned long vaddr, unsigned long end)
 {
 	phys_addr_t phys_addr;
 	pud_t *pudp, *base_pud;
 	unsigned long next;
 
-	if (early) {
-		/*
-		 * We can't use pgd_page_vaddr here as it would return a linear
-		 * mapping address but it is not mapped yet, but when populating
-		 * early_pg_dir, we need the physical address and when populating
-		 * swapper_pg_dir, we need the kernel virtual address so use
-		 * pt_ops facility.
-		 */
-		base_pud = pt_ops.get_pud_virt(pfn_to_phys(_pgd_pfn(*pgd)));
-	} else if (pgd_none(*pgd)) {
+	if (pgd_none(*pgd)) {
 		base_pud = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
 		memcpy(base_pud, (void *)kasan_early_shadow_pud,
 			sizeof(pud_t) * PTRS_PER_PUD);
@@ -130,16 +120,10 @@ static void __init kasan_populate_pud(pgd_t *pgd,
 		next = pud_addr_end(vaddr, end);
 
 		if (pud_none(*pudp) && IS_ALIGNED(vaddr, PUD_SIZE) && (next - vaddr) >= PUD_SIZE) {
-			if (early) {
-				phys_addr = __pa(((uintptr_t)kasan_early_shadow_pmd));
-				set_pud(pudp, pfn_pud(PFN_DOWN(phys_addr), PAGE_TABLE));
+			phys_addr = memblock_phys_alloc(PUD_SIZE, PUD_SIZE);
+			if (phys_addr) {
+				set_pud(pudp, pfn_pud(PFN_DOWN(phys_addr), PAGE_KERNEL));
 				continue;
-			} else {
-				phys_addr = memblock_phys_alloc(PUD_SIZE, PUD_SIZE);
-				if (phys_addr) {
-					set_pud(pudp, pfn_pud(PFN_DOWN(phys_addr), PAGE_KERNEL));
-					continue;
-				}
 			}
 		}
 
@@ -152,34 +136,21 @@ static void __init kasan_populate_pud(pgd_t *pgd,
 	 * 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.
 	 */
-	if (!early)
-		set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(base_pud)), PAGE_TABLE));
+	set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(base_pud)), PAGE_TABLE));
 }
 
 static void __init kasan_populate_p4d(pgd_t *pgd,
-				      unsigned long vaddr, unsigned long end,
-				      bool early)
+				      unsigned long vaddr, unsigned long end)
 {
 	phys_addr_t phys_addr;
 	p4d_t *p4dp, *base_p4d;
 	unsigned long next;
 
-	if (early) {
-		/*
-		 * We can't use pgd_page_vaddr here as it would return a linear
-		 * mapping address but it is not mapped yet, but when populating
-		 * early_pg_dir, we need the physical address and when populating
-		 * swapper_pg_dir, we need the kernel virtual address so use
-		 * pt_ops facility.
-		 */
-		base_p4d = pt_ops.get_p4d_virt(pfn_to_phys(_pgd_pfn(*pgd)));
-	} else {
-		base_p4d = (p4d_t *)pgd_page_vaddr(*pgd);
-		if (base_p4d == lm_alias(kasan_early_shadow_p4d)) {
-			base_p4d = memblock_alloc(PTRS_PER_PUD * sizeof(p4d_t), PAGE_SIZE);
-			memcpy(base_p4d, (void *)kasan_early_shadow_p4d,
-				sizeof(p4d_t) * PTRS_PER_P4D);
-		}
+	base_p4d = (p4d_t *)pgd_page_vaddr(*pgd);
+	if (base_p4d == lm_alias(kasan_early_shadow_p4d)) {
+		base_p4d = memblock_alloc(PTRS_PER_PUD * sizeof(p4d_t), PAGE_SIZE);
+		memcpy(base_p4d, (void *)kasan_early_shadow_p4d,
+		       sizeof(p4d_t) * PTRS_PER_P4D);
 	}
 
 	p4dp = base_p4d + p4d_index(vaddr);
@@ -188,20 +159,14 @@ static void __init kasan_populate_p4d(pgd_t *pgd,
 		next = p4d_addr_end(vaddr, end);
 
 		if (p4d_none(*p4dp) && IS_ALIGNED(vaddr, P4D_SIZE) && (next - vaddr) >= P4D_SIZE) {
-			if (early) {
-				phys_addr = __pa(((uintptr_t)kasan_early_shadow_pud));
-				set_p4d(p4dp, pfn_p4d(PFN_DOWN(phys_addr), PAGE_TABLE));
+			phys_addr = memblock_phys_alloc(P4D_SIZE, P4D_SIZE);
+			if (phys_addr) {
+				set_p4d(p4dp, pfn_p4d(PFN_DOWN(phys_addr), PAGE_KERNEL));
 				continue;
-			} else {
-				phys_addr = memblock_phys_alloc(P4D_SIZE, P4D_SIZE);
-				if (phys_addr) {
-					set_p4d(p4dp, pfn_p4d(PFN_DOWN(phys_addr), PAGE_KERNEL));
-					continue;
-				}
 			}
 		}
 
-		kasan_populate_pud((pgd_t *)p4dp, vaddr, next, early);
+		kasan_populate_pud((pgd_t *)p4dp, vaddr, next);
 	} while (p4dp++, vaddr = next, vaddr != end);
 
 	/*
@@ -210,8 +175,7 @@ static void __init kasan_populate_p4d(pgd_t *pgd,
 	 * 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.
 	 */
-	if (!early)
-		set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(base_p4d)), PAGE_TABLE));
+	set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(base_p4d)), PAGE_TABLE));
 }
 
 #define kasan_early_shadow_pgd_next			(pgtable_l5_enabled ?	\
@@ -219,16 +183,15 @@ static void __init kasan_populate_p4d(pgd_t *pgd,
 							(pgtable_l4_enabled ?	\
 				(uintptr_t)kasan_early_shadow_pud :		\
 				(uintptr_t)kasan_early_shadow_pmd))
-#define kasan_populate_pgd_next(pgdp, vaddr, next, early)			\
+#define kasan_populate_pgd_next(pgdp, vaddr, next)				\
 		(pgtable_l5_enabled ?						\
-		kasan_populate_p4d(pgdp, vaddr, next, early) :			\
+		kasan_populate_p4d(pgdp, vaddr, next) :				\
 		(pgtable_l4_enabled ?						\
-			kasan_populate_pud(pgdp, vaddr, next, early) :		\
+			kasan_populate_pud(pgdp, vaddr, next) :			\
 			kasan_populate_pmd((pud_t *)pgdp, vaddr, next)))
 
 static void __init kasan_populate_pgd(pgd_t *pgdp,
-				      unsigned long vaddr, unsigned long end,
-				      bool early)
+				      unsigned long vaddr, unsigned long end)
 {
 	phys_addr_t phys_addr;
 	unsigned long next;
@@ -237,11 +200,7 @@ static void __init kasan_populate_pgd(pgd_t *pgdp,
 		next = pgd_addr_end(vaddr, end);
 
 		if (IS_ALIGNED(vaddr, PGDIR_SIZE) && (next - vaddr) >= PGDIR_SIZE) {
-			if (early) {
-				phys_addr = __pa((uintptr_t)kasan_early_shadow_pgd_next);
-				set_pgd(pgdp, pfn_pgd(PFN_DOWN(phys_addr), PAGE_TABLE));
-				continue;
-			} else if (pgd_page_vaddr(*pgdp) ==
+			if (pgd_page_vaddr(*pgdp) ==
 				   (unsigned long)lm_alias(kasan_early_shadow_pgd_next)) {
 				/*
 				 * pgdp can't be none since kasan_early_init
@@ -258,7 +217,95 @@ static void __init kasan_populate_pgd(pgd_t *pgdp,
 			}
 		}
 
-		kasan_populate_pgd_next(pgdp, vaddr, next, early);
+		kasan_populate_pgd_next(pgdp, vaddr, next);
+	} while (pgdp++, vaddr = next, vaddr != end);
+}
+
+static void __init kasan_early_populate_pud(p4d_t *p4dp,
+					    unsigned long vaddr,
+					    unsigned long end)
+{
+	pud_t *pudp, *base_pud;
+	phys_addr_t phys_addr;
+	unsigned long next;
+
+	if (!pgtable_l4_enabled) {
+		pudp = (pud_t *)p4dp;
+	} else {
+		base_pud = pt_ops.get_pud_virt(pfn_to_phys(_p4d_pfn(*p4dp)));
+		pudp = base_pud + pud_index(vaddr);
+	}
+
+	do {
+		next = pud_addr_end(vaddr, end);
+
+		if (pud_none(*pudp) && IS_ALIGNED(vaddr, PUD_SIZE) &&
+		    (next - vaddr) >= PUD_SIZE) {
+			phys_addr = __pa((uintptr_t)kasan_early_shadow_pmd);
+			set_pud(pudp, pfn_pud(PFN_DOWN(phys_addr), PAGE_TABLE));
+			continue;
+		}
+
+		BUG();
+	} while (pudp++, vaddr = next, vaddr != end);
+}
+
+static void __init kasan_early_populate_p4d(pgd_t *pgdp,
+					    unsigned long vaddr,
+					    unsigned long end)
+{
+	p4d_t *p4dp, *base_p4d;
+	phys_addr_t phys_addr;
+	unsigned long next;
+
+	/*
+	 * We can't use pgd_page_vaddr here as it would return a linear
+	 * mapping address but it is not mapped yet, but when populating
+	 * early_pg_dir, we need the physical address and when populating
+	 * swapper_pg_dir, we need the kernel virtual address so use
+	 * pt_ops facility.
+	 * Note that this test is then completely equivalent to
+	 * p4dp = p4d_offset(pgdp, vaddr)
+	 */
+	if (!pgtable_l5_enabled) {
+		p4dp = (p4d_t *)pgdp;
+	} else {
+		base_p4d = pt_ops.get_p4d_virt(pfn_to_phys(_pgd_pfn(*pgdp)));
+		p4dp = base_p4d + p4d_index(vaddr);
+	}
+
+	do {
+		next = p4d_addr_end(vaddr, end);
+
+		if (p4d_none(*p4dp) && IS_ALIGNED(vaddr, P4D_SIZE) &&
+		    (next - vaddr) >= P4D_SIZE) {
+			phys_addr = __pa((uintptr_t)kasan_early_shadow_pud);
+			set_p4d(p4dp, pfn_p4d(PFN_DOWN(phys_addr), PAGE_TABLE));
+			continue;
+		}
+
+		kasan_early_populate_pud(p4dp, vaddr, next);
+	} while (p4dp++, vaddr = next, vaddr != end);
+}
+
+static void __init kasan_early_populate_pgd(pgd_t *pgdp,
+					    unsigned long vaddr,
+					    unsigned long end)
+{
+	phys_addr_t phys_addr;
+	unsigned long next;
+
+	do {
+		next = pgd_addr_end(vaddr, end);
+
+		if (pgd_none(*pgdp) && IS_ALIGNED(vaddr, PGDIR_SIZE) &&
+		    (next - vaddr) >= PGDIR_SIZE) {
+			phys_addr = __pa((uintptr_t)kasan_early_shadow_p4d);
+			set_pgd(pgdp, pfn_pgd(PFN_DOWN(phys_addr), PAGE_TABLE));
+			continue;
+		}
+
+		kasan_early_populate_p4d(pgdp, vaddr, next);
 	} while (pgdp++, vaddr = next, vaddr != end);
 }
 
@@ -295,16 +342,16 @@ asmlinkage void __init kasan_early_init(void)
 					PAGE_TABLE));
 	}
 
-	kasan_populate_pgd(early_pg_dir + pgd_index(KASAN_SHADOW_START),
-			   KASAN_SHADOW_START, KASAN_SHADOW_END, true);
+	kasan_early_populate_pgd(early_pg_dir + pgd_index(KASAN_SHADOW_START),
+				 KASAN_SHADOW_START, KASAN_SHADOW_END);
 
 	local_flush_tlb_all();
 }
 
 void __init kasan_swapper_init(void)
 {
-	kasan_populate_pgd(pgd_offset_k(KASAN_SHADOW_START),
-			   KASAN_SHADOW_START, KASAN_SHADOW_END, true);
+	kasan_early_populate_pgd(pgd_offset_k(KASAN_SHADOW_START),
+				 KASAN_SHADOW_START, KASAN_SHADOW_END);
 
 	local_flush_tlb_all();
 }
@@ -314,7 +361,7 @@ static void __init kasan_populate(void *start, void *end)
 	unsigned long vaddr = (unsigned long)start & PAGE_MASK;
 	unsigned long vend = PAGE_ALIGN((unsigned long)end);
 
-	kasan_populate_pgd(pgd_offset_k(vaddr), vaddr, vend, false);
+	kasan_populate_pgd(pgd_offset_k(vaddr), vaddr, vend);
 
 	local_flush_tlb_all();
 	memset(start, KASAN_SHADOW_INIT, end - start);
-- 
2.37.2

Re: [PATCH v4 1/6] riscv: Split early and final KASAN population functions

[Björn Töpel]

Alexandre Ghiti <alexghiti@rivosinc.com> writes:

> This is a preliminary work that allows to make the code more
> understandable.
>
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
> ---
>  arch/riscv/mm/kasan_init.c | 185 +++++++++++++++++++++++--------------
>  1 file changed, 116 insertions(+), 69 deletions(-)

Reviewed-by: Björn Töpel <bjorn@rivosinc.com>

[PATCH v4 2/6] riscv: Rework kasan population functions

[Alexandre Ghiti]

Our previous kasan population implementation used to have the final kasan
shadow region mapped with kasan_early_shadow_page, because we did not clean
the early mapping and then we had to populate the kasan region "in-place"
which made the code cumbersome.

So now we clear the early mapping, establish a temporary mapping while we
populate the kasan shadow region with just the kernel regions that will
be used.

This new version uses the "generic" way of going through a page table
that may be folded at runtime (avoid the XXX_next macros).

It was tested with outline instrumentation on an Ubuntu kernel
configuration successfully.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 arch/riscv/mm/kasan_init.c | 361 +++++++++++++++++++------------------
 1 file changed, 183 insertions(+), 178 deletions(-)

diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index 2a48eba6bd08..8fc0efcf905c 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -18,58 +18,48 @@
  * For sv39, the region is aligned on PGDIR_SIZE so we only need to populate
  * the page global directory with kasan_early_shadow_pmd.
  *
- * For sv48 and sv57, the region is not aligned on PGDIR_SIZE so the mapping
- * must be divided as follows:
- * - the first PGD entry, although incomplete, is populated with
- *   kasan_early_shadow_pud/p4d
- * - the PGD entries in the middle are populated with kasan_early_shadow_pud/p4d
- * - the last PGD entry is shared with the kernel mapping so populated at the
- *   lower levels pud/p4d
- *
- * In addition, when shallow populating a kasan region (for example vmalloc),
- * this region may also not be aligned on PGDIR size, so we must go down to the
- * pud level too.
+ * For sv48 and sv57, the region start is aligned on PGDIR_SIZE whereas the end
+ * region is not and then we have to go down to the PUD level.
  */
 
 extern pgd_t early_pg_dir[PTRS_PER_PGD];
+pgd_t tmp_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
+p4d_t tmp_p4d[PTRS_PER_P4D] __page_aligned_bss;
+pud_t tmp_pud[PTRS_PER_PUD] __page_aligned_bss;
 
 static void __init kasan_populate_pte(pmd_t *pmd, unsigned long vaddr, unsigned long end)
 {
 	phys_addr_t phys_addr;
-	pte_t *ptep, *base_pte;
+	pte_t *ptep, *p;
 
-	if (pmd_none(*pmd))
-		base_pte = memblock_alloc(PTRS_PER_PTE * sizeof(pte_t), PAGE_SIZE);
-	else
-		base_pte = (pte_t *)pmd_page_vaddr(*pmd);
+	if (pmd_none(*pmd)) {
+		p = memblock_alloc(PTRS_PER_PTE * sizeof(pte_t), PAGE_SIZE);
+		set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa(p)), PAGE_TABLE));
+	}
 
-	ptep = base_pte + pte_index(vaddr);
+	ptep = pte_offset_kernel(pmd, vaddr);
 
 	do {
 		if (pte_none(*ptep)) {
 			phys_addr = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
 			set_pte(ptep, pfn_pte(PFN_DOWN(phys_addr), PAGE_KERNEL));
+			memset(__va(phys_addr), KASAN_SHADOW_INIT, PAGE_SIZE);
 		}
 	} while (ptep++, vaddr += PAGE_SIZE, vaddr != end);
-
-	set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa(base_pte)), PAGE_TABLE));
 }
 
 static void __init kasan_populate_pmd(pud_t *pud, unsigned long vaddr, unsigned long end)
 {
 	phys_addr_t phys_addr;
-	pmd_t *pmdp, *base_pmd;
+	pmd_t *pmdp, *p;
 	unsigned long next;
 
 	if (pud_none(*pud)) {
-		base_pmd = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
-	} else {
-		base_pmd = (pmd_t *)pud_pgtable(*pud);
-		if (base_pmd == lm_alias(kasan_early_shadow_pmd))
-			base_pmd = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
+		p = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
+		set_pud(pud, pfn_pud(PFN_DOWN(__pa(p)), PAGE_TABLE));
 	}
 
-	pmdp = base_pmd + pmd_index(vaddr);
+	pmdp = pmd_offset(pud, vaddr);
 
 	do {
 		next = pmd_addr_end(vaddr, end);
@@ -78,43 +68,28 @@ static void __init kasan_populate_pmd(pud_t *pud, unsigned long vaddr, unsigned
 			phys_addr = memblock_phys_alloc(PMD_SIZE, PMD_SIZE);
 			if (phys_addr) {
 				set_pmd(pmdp, pfn_pmd(PFN_DOWN(phys_addr), PAGE_KERNEL));
+				memset(__va(phys_addr), KASAN_SHADOW_INIT, PMD_SIZE);
 				continue;
 			}
 		}
 
 		kasan_populate_pte(pmdp, vaddr, next);
 	} 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_pud(pud, pfn_pud(PFN_DOWN(__pa(base_pmd)), PAGE_TABLE));
 }
 
-static void __init kasan_populate_pud(pgd_t *pgd,
+static void __init kasan_populate_pud(p4d_t *p4d,
 				      unsigned long vaddr, unsigned long end)
 {
 	phys_addr_t phys_addr;
-	pud_t *pudp, *base_pud;
+	pud_t *pudp, *p;
 	unsigned long next;
 
-	if (pgd_none(*pgd)) {
-		base_pud = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
-		memcpy(base_pud, (void *)kasan_early_shadow_pud,
-			sizeof(pud_t) * PTRS_PER_PUD);
-	} else {
-		base_pud = (pud_t *)pgd_page_vaddr(*pgd);
-		if (base_pud == lm_alias(kasan_early_shadow_pud)) {
-			base_pud = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
-			memcpy(base_pud, (void *)kasan_early_shadow_pud,
-			       sizeof(pud_t) * PTRS_PER_PUD);
-		}
+	if (p4d_none(*p4d)) {
+		p = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
+		set_p4d(p4d, pfn_p4d(PFN_DOWN(__pa(p)), PAGE_TABLE));
 	}
 
-	pudp = base_pud + pud_index(vaddr);
+	pudp = pud_offset(p4d, vaddr);
 
 	do {
 		next = pud_addr_end(vaddr, end);
@@ -123,37 +98,28 @@ static void __init kasan_populate_pud(pgd_t *pgd,
 			phys_addr = memblock_phys_alloc(PUD_SIZE, PUD_SIZE);
 			if (phys_addr) {
 				set_pud(pudp, pfn_pud(PFN_DOWN(phys_addr), PAGE_KERNEL));
+				memset(__va(phys_addr), KASAN_SHADOW_INIT, PUD_SIZE);
 				continue;
 			}
 		}
 
 		kasan_populate_pmd(pudp, vaddr, next);
 	} while (pudp++, 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(base_pud)), PAGE_TABLE));
 }
 
 static void __init kasan_populate_p4d(pgd_t *pgd,
 				      unsigned long vaddr, unsigned long end)
 {
 	phys_addr_t phys_addr;
-	p4d_t *p4dp, *base_p4d;
+	p4d_t *p4dp, *p;
 	unsigned long next;
 
-	base_p4d = (p4d_t *)pgd_page_vaddr(*pgd);
-	if (base_p4d == lm_alias(kasan_early_shadow_p4d)) {
-		base_p4d = memblock_alloc(PTRS_PER_PUD * sizeof(p4d_t), PAGE_SIZE);
-		memcpy(base_p4d, (void *)kasan_early_shadow_p4d,
-		       sizeof(p4d_t) * PTRS_PER_P4D);
+	if (pgd_none(*pgd)) {
+		p = memblock_alloc(PTRS_PER_P4D * sizeof(p4d_t), PAGE_SIZE);
+		set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(p)), PAGE_TABLE));
 	}
 
-	p4dp = base_p4d + p4d_index(vaddr);
+	p4dp = p4d_offset(pgd, vaddr);
 
 	do {
 		next = p4d_addr_end(vaddr, end);
@@ -162,34 +128,15 @@ static void __init kasan_populate_p4d(pgd_t *pgd,
 			phys_addr = memblock_phys_alloc(P4D_SIZE, P4D_SIZE);
 			if (phys_addr) {
 				set_p4d(p4dp, pfn_p4d(PFN_DOWN(phys_addr), PAGE_KERNEL));
+				memset(__va(phys_addr), KASAN_SHADOW_INIT, P4D_SIZE);
 				continue;
 			}
 		}
 
-		kasan_populate_pud((pgd_t *)p4dp, vaddr, next);
+		kasan_populate_pud(p4dp, vaddr, next);
 	} while (p4dp++, vaddr = next, vaddr != end);
-
-	/*
-	 * Wait for the whole P4D to be populated before setting the P4D in
-	 * the page table, otherwise, if we did set the P4D 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(base_p4d)), PAGE_TABLE));
 }
 
-#define kasan_early_shadow_pgd_next			(pgtable_l5_enabled ?	\
-				(uintptr_t)kasan_early_shadow_p4d :		\
-							(pgtable_l4_enabled ?	\
-				(uintptr_t)kasan_early_shadow_pud :		\
-				(uintptr_t)kasan_early_shadow_pmd))
-#define kasan_populate_pgd_next(pgdp, vaddr, next)				\
-		(pgtable_l5_enabled ?						\
-		kasan_populate_p4d(pgdp, vaddr, next) :				\
-		(pgtable_l4_enabled ?						\
-			kasan_populate_pud(pgdp, vaddr, next) :			\
-			kasan_populate_pmd((pud_t *)pgdp, vaddr, next)))
-
 static void __init kasan_populate_pgd(pgd_t *pgdp,
 				      unsigned long vaddr, unsigned long end)
 {
@@ -199,25 +146,86 @@ static void __init kasan_populate_pgd(pgd_t *pgdp,
 	do {
 		next = pgd_addr_end(vaddr, end);
 
-		if (IS_ALIGNED(vaddr, PGDIR_SIZE) && (next - vaddr) >= PGDIR_SIZE) {
-			if (pgd_page_vaddr(*pgdp) ==
-				   (unsigned long)lm_alias(kasan_early_shadow_pgd_next)) {
-				/*
-				 * pgdp can't be none since kasan_early_init
-				 * initialized all KASAN shadow region with
-				 * kasan_early_shadow_pud: if this is still the
-				 * case, that means we can try to allocate a
-				 * hugepage as a replacement.
-				 */
-				phys_addr = memblock_phys_alloc(PGDIR_SIZE, PGDIR_SIZE);
-				if (phys_addr) {
-					set_pgd(pgdp, pfn_pgd(PFN_DOWN(phys_addr), PAGE_KERNEL));
-					continue;
-				}
+		if (pgd_none(*pgdp) && 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));
+				memset(__va(phys_addr), KASAN_SHADOW_INIT, PGDIR_SIZE);
+				continue;
 			}
 		}
 
-		kasan_populate_pgd_next(pgdp, vaddr, next);
+		kasan_populate_p4d(pgdp, vaddr, next);
+	} while (pgdp++, vaddr = next, vaddr != end);
+}
+
+static void __init kasan_early_clear_pud(p4d_t *p4dp,
+					 unsigned long vaddr, unsigned long end)
+{
+	pud_t *pudp, *base_pud;
+	unsigned long next;
+
+	if (!pgtable_l4_enabled) {
+		pudp = (pud_t *)p4dp;
+	} else {
+		base_pud = pt_ops.get_pud_virt(pfn_to_phys(_p4d_pfn(*p4dp)));
+		pudp = base_pud + pud_index(vaddr);
+	}
+
+	do {
+		next = pud_addr_end(vaddr, end);
+
+		if (IS_ALIGNED(vaddr, PUD_SIZE) && (next - vaddr) >= PUD_SIZE) {
+			pud_clear(pudp);
+			continue;
+		}
+
+		BUG();
+	} while (pudp++, vaddr = next, vaddr != end);
+}
+
+static void __init kasan_early_clear_p4d(pgd_t *pgdp,
+					 unsigned long vaddr, unsigned long end)
+{
+	p4d_t *p4dp, *base_p4d;
+	unsigned long next;
+
+	if (!pgtable_l5_enabled) {
+		p4dp = (p4d_t *)pgdp;
+	} else {
+		base_p4d = pt_ops.get_p4d_virt(pfn_to_phys(_pgd_pfn(*pgdp)));
+		p4dp = base_p4d + p4d_index(vaddr);
+	}
+
+	do {
+		next = p4d_addr_end(vaddr, end);
+
+		if (pgtable_l4_enabled && IS_ALIGNED(vaddr, P4D_SIZE) &&
+		    (next - vaddr) >= P4D_SIZE) {
+			p4d_clear(p4dp);
+			continue;
+		}
+
+		kasan_early_clear_pud(p4dp, vaddr, next);
+	} while (p4dp++, vaddr = next, vaddr != end);
+}
+
+static void __init kasan_early_clear_pgd(pgd_t *pgdp,
+					 unsigned long vaddr, unsigned long end)
+{
+	unsigned long next;
+
+	do {
+		next = pgd_addr_end(vaddr, end);
+
+		if (pgtable_l5_enabled && IS_ALIGNED(vaddr, PGDIR_SIZE) &&
+		    (next - vaddr) >= PGDIR_SIZE) {
+			pgd_clear(pgdp);
+			continue;
+		}
+
+		kasan_early_clear_p4d(pgdp, vaddr, next);
 	} while (pgdp++, vaddr = next, vaddr != end);
 }
 
@@ -362,117 +370,64 @@ static void __init kasan_populate(void *start, void *end)
 	unsigned long vend = PAGE_ALIGN((unsigned long)end);
 
 	kasan_populate_pgd(pgd_offset_k(vaddr), vaddr, vend);
-
-	local_flush_tlb_all();
-	memset(start, KASAN_SHADOW_INIT, end - start);
-}
-
-static void __init kasan_shallow_populate_pmd(pgd_t *pgdp,
-					      unsigned long vaddr, unsigned long end)
-{
-	unsigned long next;
-	pmd_t *pmdp, *base_pmd;
-	bool is_kasan_pte;
-
-	base_pmd = (pmd_t *)pgd_page_vaddr(*pgdp);
-	pmdp = base_pmd + pmd_index(vaddr);
-
-	do {
-		next = pmd_addr_end(vaddr, end);
-		is_kasan_pte = (pmd_pgtable(*pmdp) == lm_alias(kasan_early_shadow_pte));
-
-		if (is_kasan_pte)
-			pmd_clear(pmdp);
-	} while (pmdp++, vaddr = next, vaddr != end);
 }
 
-static void __init kasan_shallow_populate_pud(pgd_t *pgdp,
+static void __init kasan_shallow_populate_pud(p4d_t *p4d,
 					      unsigned long vaddr, unsigned long end)
 {
 	unsigned long next;
-	pud_t *pudp, *base_pud;
-	pmd_t *base_pmd;
-	bool is_kasan_pmd;
-
-	base_pud = (pud_t *)pgd_page_vaddr(*pgdp);
-	pudp = base_pud + pud_index(vaddr);
+	void *p;
+	pud_t *pud_k = pud_offset(p4d, vaddr);
 
 	do {
 		next = pud_addr_end(vaddr, end);
-		is_kasan_pmd = (pud_pgtable(*pudp) == lm_alias(kasan_early_shadow_pmd));
 
-		if (!is_kasan_pmd)
-			continue;
-
-		base_pmd = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
-		set_pud(pudp, pfn_pud(PFN_DOWN(__pa(base_pmd)), PAGE_TABLE));
-
-		if (IS_ALIGNED(vaddr, PUD_SIZE) && (next - vaddr) >= PUD_SIZE)
+		if (pud_none(*pud_k)) {
+			p = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+			set_pud(pud_k, pfn_pud(PFN_DOWN(__pa(p)), PAGE_TABLE));
 			continue;
+		}
 
-		memcpy(base_pmd, (void *)kasan_early_shadow_pmd, PAGE_SIZE);
-		kasan_shallow_populate_pmd((pgd_t *)pudp, vaddr, next);
-	} while (pudp++, vaddr = next, vaddr != end);
+		BUG();
+	} while (pud_k++, vaddr = next, vaddr != end);
 }
 
-static void __init kasan_shallow_populate_p4d(pgd_t *pgdp,
+static void __init kasan_shallow_populate_p4d(pgd_t *pgd,
 					      unsigned long vaddr, unsigned long end)
 {
 	unsigned long next;
-	p4d_t *p4dp, *base_p4d;
-	pud_t *base_pud;
-	bool is_kasan_pud;
-
-	base_p4d = (p4d_t *)pgd_page_vaddr(*pgdp);
-	p4dp = base_p4d + p4d_index(vaddr);
+	void *p;
+	p4d_t *p4d_k = p4d_offset(pgd, vaddr);
 
 	do {
 		next = p4d_addr_end(vaddr, end);
-		is_kasan_pud = (p4d_pgtable(*p4dp) == lm_alias(kasan_early_shadow_pud));
-
-		if (!is_kasan_pud)
-			continue;
-
-		base_pud = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
-		set_p4d(p4dp, pfn_p4d(PFN_DOWN(__pa(base_pud)), PAGE_TABLE));
 
-		if (IS_ALIGNED(vaddr, P4D_SIZE) && (next - vaddr) >= P4D_SIZE)
+		if (p4d_none(*p4d_k)) {
+			p = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+			set_p4d(p4d_k, pfn_p4d(PFN_DOWN(__pa(p)), PAGE_TABLE));
 			continue;
+		}
 
-		memcpy(base_pud, (void *)kasan_early_shadow_pud, PAGE_SIZE);
-		kasan_shallow_populate_pud((pgd_t *)p4dp, vaddr, next);
-	} while (p4dp++, vaddr = next, vaddr != end);
+		kasan_shallow_populate_pud(p4d_k, vaddr, end);
+	} while (p4d_k++, vaddr = next, vaddr != end);
 }
 
-#define kasan_shallow_populate_pgd_next(pgdp, vaddr, next)			\
-		(pgtable_l5_enabled ?						\
-		kasan_shallow_populate_p4d(pgdp, vaddr, next) :			\
-		(pgtable_l4_enabled ?						\
-		kasan_shallow_populate_pud(pgdp, vaddr, next) :			\
-		kasan_shallow_populate_pmd(pgdp, vaddr, next)))
-
 static void __init kasan_shallow_populate_pgd(unsigned long vaddr, unsigned long end)
 {
 	unsigned long next;
 	void *p;
 	pgd_t *pgd_k = pgd_offset_k(vaddr);
-	bool is_kasan_pgd_next;
 
 	do {
 		next = pgd_addr_end(vaddr, end);
-		is_kasan_pgd_next = (pgd_page_vaddr(*pgd_k) ==
-				     (unsigned long)lm_alias(kasan_early_shadow_pgd_next));
 
-		if (is_kasan_pgd_next) {
+		if (pgd_none(*pgd_k)) {
 			p = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
 			set_pgd(pgd_k, pfn_pgd(PFN_DOWN(__pa(p)), PAGE_TABLE));
-		}
-
-		if (IS_ALIGNED(vaddr, PGDIR_SIZE) && (next - vaddr) >= PGDIR_SIZE)
 			continue;
+		}
 
-		memcpy(p, (void *)kasan_early_shadow_pgd_next, PAGE_SIZE);
-		kasan_shallow_populate_pgd_next(pgd_k, vaddr, next);
+		kasan_shallow_populate_p4d(pgd_k, vaddr, next);
 	} while (pgd_k++, vaddr = next, vaddr != end);
 }
 
@@ -482,7 +437,37 @@ static void __init kasan_shallow_populate(void *start, void *end)
 	unsigned long vend = PAGE_ALIGN((unsigned long)end);
 
 	kasan_shallow_populate_pgd(vaddr, vend);
-	local_flush_tlb_all();
+}
+
+static void create_tmp_mapping(void)
+{
+	void *ptr;
+	p4d_t *base_p4d;
+
+	/*
+	 * We need to clean the early mapping: this is hard to achieve "in-place",
+	 * so install a temporary mapping like arm64 and x86 do.
+	 */
+	memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(pgd_t) * PTRS_PER_PGD);
+
+	/* Copy the last p4d since it is shared with the kernel mapping. */
+	if (pgtable_l5_enabled) {
+		ptr = (p4d_t *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
+		memcpy(tmp_p4d, ptr, sizeof(p4d_t) * PTRS_PER_P4D);
+		set_pgd(&tmp_pg_dir[pgd_index(KASAN_SHADOW_END)],
+			pfn_pgd(PFN_DOWN(__pa(tmp_p4d)), PAGE_TABLE));
+		base_p4d = tmp_p4d;
+	} else {
+		base_p4d = (p4d_t *)tmp_pg_dir;
+	}
+
+	/* Copy the last pud since it is shared with the kernel mapping. */
+	if (pgtable_l4_enabled) {
+		ptr = (pud_t *)p4d_page_vaddr(*(base_p4d + p4d_index(KASAN_SHADOW_END)));
+		memcpy(tmp_pud, ptr, sizeof(pud_t) * PTRS_PER_PUD);
+		set_p4d(&base_p4d[p4d_index(KASAN_SHADOW_END)],
+			pfn_p4d(PFN_DOWN(__pa(tmp_pud)), PAGE_TABLE));
+	}
 }
 
 void __init kasan_init(void)
@@ -490,10 +475,27 @@ void __init kasan_init(void)
 	phys_addr_t p_start, p_end;
 	u64 i;
 
-	if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
+	create_tmp_mapping();
+	csr_write(CSR_SATP, PFN_DOWN(__pa(tmp_pg_dir)) | satp_mode);
+
+	kasan_early_clear_pgd(pgd_offset_k(KASAN_SHADOW_START),
+			      KASAN_SHADOW_START, KASAN_SHADOW_END);
+
+	kasan_populate_early_shadow((void *)kasan_mem_to_shadow((void *)FIXADDR_START),
+				    (void *)kasan_mem_to_shadow((void *)VMALLOC_START));
+
+	if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
 		kasan_shallow_populate(
 			(void *)kasan_mem_to_shadow((void *)VMALLOC_START),
 			(void *)kasan_mem_to_shadow((void *)VMALLOC_END));
+		/* Shallow populate modules and BPF which are vmalloc-allocated */
+		kasan_shallow_populate(
+			(void *)kasan_mem_to_shadow((void *)MODULES_VADDR),
+			(void *)kasan_mem_to_shadow((void *)MODULES_END));
+	} else {
+		kasan_populate_early_shadow((void *)kasan_mem_to_shadow((void *)VMALLOC_START),
+					    (void *)kasan_mem_to_shadow((void *)VMALLOC_END));
+	}
 
 	/* Populate the linear mapping */
 	for_each_mem_range(i, &p_start, &p_end) {
@@ -506,8 +508,8 @@ void __init kasan_init(void)
 		kasan_populate(kasan_mem_to_shadow(start), kasan_mem_to_shadow(end));
 	}
 
-	/* Populate kernel, BPF, modules mapping */
-	kasan_populate(kasan_mem_to_shadow((const void *)MODULES_VADDR),
+	/* Populate kernel */
+	kasan_populate(kasan_mem_to_shadow((const void *)MODULES_END),
 		       kasan_mem_to_shadow((const void *)MODULES_VADDR + SZ_2G));
 
 	for (i = 0; i < PTRS_PER_PTE; i++)
@@ -518,4 +520,7 @@ void __init kasan_init(void)
 
 	memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
 	init_task.kasan_depth = 0;
+
+	csr_write(CSR_SATP, PFN_DOWN(__pa(swapper_pg_dir)) | satp_mode);
+	local_flush_tlb_all();
 }
-- 
2.37.2

Re: [PATCH v4 2/6] riscv: Rework kasan population functions

[Björn Töpel]

Alexandre Ghiti <alexghiti@rivosinc.com> writes:

> Our previous kasan population implementation used to have the final kasan
> shadow region mapped with kasan_early_shadow_page, because we did not clean
> the early mapping and then we had to populate the kasan region "in-place"
> which made the code cumbersome.
>
> So now we clear the early mapping, establish a temporary mapping while we
> populate the kasan shadow region with just the kernel regions that will
> be used.
>
> This new version uses the "generic" way of going through a page table
> that may be folded at runtime (avoid the XXX_next macros).
>
> It was tested with outline instrumentation on an Ubuntu kernel
> configuration successfully.
>
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>

(One minor nit, that can be addressed later.)

Reviewed-by: Björn Töpel <bjorn@rivosinc.com>

>  arch/riscv/mm/kasan_init.c | 361 +++++++++++++++++++------------------
>  1 file changed, 183 insertions(+), 178 deletions(-)


> @@ -482,7 +437,37 @@ static void __init kasan_shallow_populate(void *start, void *end)
>  	unsigned long vend = PAGE_ALIGN((unsigned long)end);
>  
>  	kasan_shallow_populate_pgd(vaddr, vend);
> -	local_flush_tlb_all();
> +}
> +
> +static void create_tmp_mapping(void)
> +{
> +	void *ptr;
> +	p4d_t *base_p4d;
> +
> +	/*
> +	 * We need to clean the early mapping: this is hard to achieve "in-place",
> +	 * so install a temporary mapping like arm64 and x86 do.
> +	 */
> +	memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(pgd_t) * PTRS_PER_PGD);
> +
> +	/* Copy the last p4d since it is shared with the kernel mapping. */
> +	if (pgtable_l5_enabled) {
> +		ptr = (p4d_t *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
> +		memcpy(tmp_p4d, ptr, sizeof(p4d_t) * PTRS_PER_P4D);
> +		set_pgd(&tmp_pg_dir[pgd_index(KASAN_SHADOW_END)],
> +			pfn_pgd(PFN_DOWN(__pa(tmp_p4d)), PAGE_TABLE));
> +		base_p4d = tmp_p4d;
> +	} else {
> +		base_p4d = (p4d_t *)tmp_pg_dir;
> +	}
> +
> +	/* Copy the last pud since it is shared with the kernel mapping. */
> +	if (pgtable_l4_enabled) {
> +		ptr = (pud_t *)p4d_page_vaddr(*(base_p4d + p4d_index(KASAN_SHADOW_END)));
> +		memcpy(tmp_pud, ptr, sizeof(pud_t) * PTRS_PER_PUD);
> +		set_p4d(&base_p4d[p4d_index(KASAN_SHADOW_END)],
> +			pfn_p4d(PFN_DOWN(__pa(tmp_pud)), PAGE_TABLE));
> +	}
>  }
>  
>  void __init kasan_init(void)
> @@ -490,10 +475,27 @@ void __init kasan_init(void)
>  	phys_addr_t p_start, p_end;
>  	u64 i;
>  
> -	if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
> +	create_tmp_mapping();
> +	csr_write(CSR_SATP, PFN_DOWN(__pa(tmp_pg_dir)) | satp_mode);

Nit: Maybe add a comment, why the sfence.vma is *not* required here. I
tripped over it.


Björn

[PATCH v4 3/6] riscv: Move DTB_EARLY_BASE_VA to the kernel address space

[Alexandre Ghiti]

The early virtual address should lie in the kernel address space for
inline kasan instrumentation to succeed, otherwise kasan tries to
dereference an address that does not exist in the address space (since
kasan only maps *kernel* address space, not the userspace).

Simply use the very first address of the kernel address space for the
early fdt mapping.

It allowed an Ubuntu kernel to boot successfully with inline
instrumentation.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 arch/riscv/mm/init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 478d6763a01a..87f6a5d475a6 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -57,7 +57,7 @@ unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
 EXPORT_SYMBOL(empty_zero_page);
 
 extern char _start[];
-#define DTB_EARLY_BASE_VA      PGDIR_SIZE
+#define DTB_EARLY_BASE_VA      (ADDRESS_SPACE_END - (PTRS_PER_PGD / 2 * PGDIR_SIZE) + 1)
 void *_dtb_early_va __initdata;
 uintptr_t _dtb_early_pa __initdata;
 
-- 
2.37.2

Re: [PATCH v4 3/6] riscv: Move DTB_EARLY_BASE_VA to the kernel address space

[Björn Töpel]

Alexandre Ghiti <alexghiti@rivosinc.com> writes:

> The early virtual address should lie in the kernel address space for
> inline kasan instrumentation to succeed, otherwise kasan tries to
> dereference an address that does not exist in the address space (since
> kasan only maps *kernel* address space, not the userspace).
>
> Simply use the very first address of the kernel address space for the
> early fdt mapping.
>
> It allowed an Ubuntu kernel to boot successfully with inline
> instrumentation.
>
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Reviewed-by: Björn Töpel <bjorn@rivosinc.com>

[PATCH v4 4/6] riscv: Fix EFI stub usage of KASAN instrumented strcmp function

[Alexandre Ghiti]

The EFI stub must not use any KASAN instrumented code as the kernel
proper did not initialize the thread pointer and the mapping for the
KASAN shadow region.

Avoid using the generic strcmp function, instead use the one in
drivers/firmware/efi/libstub/string.c.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/riscv/kernel/image-vars.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/riscv/kernel/image-vars.h b/arch/riscv/kernel/image-vars.h
index 7e2962ef73f9..15616155008c 100644
--- a/arch/riscv/kernel/image-vars.h
+++ b/arch/riscv/kernel/image-vars.h
@@ -23,8 +23,6 @@
  * linked at. The routines below are all implemented in assembler in a
  * position independent manner
  */
-__efistub_strcmp		= strcmp;
-
 __efistub__start		= _start;
 __efistub__start_kernel		= _start_kernel;
 __efistub__end			= _end;
-- 
2.37.2

Re: [PATCH v4 4/6] riscv: Fix EFI stub usage of KASAN instrumented strcmp function

[Atish Patra]

On Thu, Feb 2, 2023 at 11:56 PM Alexandre Ghiti <alexghiti@rivosinc.com> wrote:
>
> The EFI stub must not use any KASAN instrumented code as the kernel
> proper did not initialize the thread pointer and the mapping for the
> KASAN shadow region.
>
> Avoid using the generic strcmp function, instead use the one in
> drivers/firmware/efi/libstub/string.c.
>
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
> Acked-by: Ard Biesheuvel <ardb@kernel.org>
> ---
>  arch/riscv/kernel/image-vars.h | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/arch/riscv/kernel/image-vars.h b/arch/riscv/kernel/image-vars.h
> index 7e2962ef73f9..15616155008c 100644
> --- a/arch/riscv/kernel/image-vars.h
> +++ b/arch/riscv/kernel/image-vars.h
> @@ -23,8 +23,6 @@
>   * linked at. The routines below are all implemented in assembler in a
>   * position independent manner
>   */
> -__efistub_strcmp               = strcmp;
> -
>  __efistub__start               = _start;
>  __efistub__start_kernel                = _start_kernel;
>  __efistub__end                 = _end;
> --
> 2.37.2
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv


Reviewed-by: Atish Patra <atishp@rivosinc.com>

-- 
Regards,
Atish

[PATCH v4 5/6] riscv: Fix ptdump when KASAN is enabled

[Alexandre Ghiti]

The KASAN shadow region was moved next to the kernel mapping but the
ptdump code was not updated and it appears to break the dump of the kernel
page table, so fix this by moving the KASAN shadow region in ptdump.

Fixes: f7ae02333d13 ("riscv: Move KASAN mapping next to the kernel mapping")
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 arch/riscv/mm/ptdump.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/riscv/mm/ptdump.c b/arch/riscv/mm/ptdump.c
index 830e7de65e3a..20a9f991a6d7 100644
--- a/arch/riscv/mm/ptdump.c
+++ b/arch/riscv/mm/ptdump.c
@@ -59,10 +59,6 @@ struct ptd_mm_info {
 };
 
 enum address_markers_idx {
-#ifdef CONFIG_KASAN
-	KASAN_SHADOW_START_NR,
-	KASAN_SHADOW_END_NR,
-#endif
 	FIXMAP_START_NR,
 	FIXMAP_END_NR,
 	PCI_IO_START_NR,
@@ -74,6 +70,10 @@ enum address_markers_idx {
 	VMALLOC_START_NR,
 	VMALLOC_END_NR,
 	PAGE_OFFSET_NR,
+#ifdef CONFIG_KASAN
+	KASAN_SHADOW_START_NR,
+	KASAN_SHADOW_END_NR,
+#endif
 #ifdef CONFIG_64BIT
 	MODULES_MAPPING_NR,
 	KERNEL_MAPPING_NR,
@@ -82,10 +82,6 @@ enum address_markers_idx {
 };
 
 static struct addr_marker address_markers[] = {
-#ifdef CONFIG_KASAN
-	{0, "Kasan shadow start"},
-	{0, "Kasan shadow end"},
-#endif
 	{0, "Fixmap start"},
 	{0, "Fixmap end"},
 	{0, "PCI I/O start"},
@@ -97,6 +93,10 @@ static struct addr_marker address_markers[] = {
 	{0, "vmalloc() area"},
 	{0, "vmalloc() end"},
 	{0, "Linear mapping"},
+#ifdef CONFIG_KASAN
+	{0, "Kasan shadow start"},
+	{0, "Kasan shadow end"},
+#endif
 #ifdef CONFIG_64BIT
 	{0, "Modules/BPF mapping"},
 	{0, "Kernel mapping"},
@@ -362,10 +362,6 @@ static int __init ptdump_init(void)
 {
 	unsigned int i, j;
 
-#ifdef CONFIG_KASAN
-	address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
-	address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
-#endif
 	address_markers[FIXMAP_START_NR].start_address = FIXADDR_START;
 	address_markers[FIXMAP_END_NR].start_address = FIXADDR_TOP;
 	address_markers[PCI_IO_START_NR].start_address = PCI_IO_START;
@@ -377,6 +373,10 @@ static int __init ptdump_init(void)
 	address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
 	address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
 	address_markers[PAGE_OFFSET_NR].start_address = PAGE_OFFSET;
+#ifdef CONFIG_KASAN
+	address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
+	address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
+#endif
 #ifdef CONFIG_64BIT
 	address_markers[MODULES_MAPPING_NR].start_address = MODULES_VADDR;
 	address_markers[KERNEL_MAPPING_NR].start_address = kernel_map.virt_addr;
-- 
2.37.2

Re: [PATCH v4 5/6] riscv: Fix ptdump when KASAN is enabled

[Björn Töpel]

Alexandre Ghiti <alexghiti@rivosinc.com> writes:

> The KASAN shadow region was moved next to the kernel mapping but the
> ptdump code was not updated and it appears to break the dump of the kernel
> page table, so fix this by moving the KASAN shadow region in ptdump.
>
> Fixes: f7ae02333d13 ("riscv: Move KASAN mapping next to the kernel mapping")
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Tested-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>

[PATCH v4 6/6] riscv: Unconditionnally select KASAN_VMALLOC if KASAN

[Alexandre Ghiti]

If KASAN is enabled, VMAP_STACK depends on KASAN_VMALLOC so enable
KASAN_VMALLOC with KASAN so that we can enable VMAP_STACK by default.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 arch/riscv/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index e2b656043abf..0f226d3261ca 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -117,6 +117,7 @@ config RISCV
 	select HAVE_RSEQ
 	select IRQ_DOMAIN
 	select IRQ_FORCED_THREADING
+	select KASAN_VMALLOC if KASAN
 	select MODULES_USE_ELF_RELA if MODULES
 	select MODULE_SECTIONS if MODULES
 	select OF
-- 
2.37.2

Re: [PATCH v4 6/6] riscv: Unconditionnally select KASAN_VMALLOC if KASAN

[Björn Töpel]

Alexandre Ghiti <alexghiti@rivosinc.com> writes:

> If KASAN is enabled, VMAP_STACK depends on KASAN_VMALLOC so enable
> KASAN_VMALLOC with KASAN so that we can enable VMAP_STACK by default.
>
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Reviewed-by: Björn Töpel <bjorn@rivosinc.com>

Re: [PATCH v4 0/6] RISC-V kasan rework

[Palmer Dabbelt]

On Fri, 3 Feb 2023 08:52:26 +0100, Alexandre Ghiti wrote:
> As described in patch 2, our current kasan implementation is intricate,
> so I tried to simplify the implementation and mimic what arm64/x86 are
> doing.
> 
> In addition it fixes UEFI bootflow with a kasan kernel and kasan inline
> instrumentation: all kasan configurations were tested on a large ubuntu
> kernel with success with KASAN_KUNIT_TEST and KASAN_MODULE_TEST.
> 
> [...]

Applied, thanks!

[1/6] riscv: Split early and final KASAN population functions
      https://git.kernel.org/palmer/c/70a3bb1e1fd9
[2/6] riscv: Rework kasan population functions
      https://git.kernel.org/palmer/c/fec8e4f66e4d
[3/6] riscv: Move DTB_EARLY_BASE_VA to the kernel address space
      https://git.kernel.org/palmer/c/1cdf594686a3
[4/6] riscv: Fix EFI stub usage of KASAN instrumented strcmp function
      https://git.kernel.org/palmer/c/415e9a115124
[5/6] riscv: Fix ptdump when KASAN is enabled
      https://git.kernel.org/palmer/c/fe0c8624d20d
[6/6] riscv: Unconditionnally select KASAN_VMALLOC if KASAN
      https://git.kernel.org/palmer/c/4cdc06c5c741

Best regards,
-- 
Palmer Dabbelt <palmer@rivosinc.com>

Re: [PATCH v4 0/6] RISC-V kasan rework

[Palmer Dabbelt]

On Tue, 07 Mar 2023 19:29:11 PST (-0800), Palmer Dabbelt wrote:
>
> On Fri, 3 Feb 2023 08:52:26 +0100, Alexandre Ghiti wrote:
>> As described in patch 2, our current kasan implementation is intricate,
>> so I tried to simplify the implementation and mimic what arm64/x86 are
>> doing.
>>
>> In addition it fixes UEFI bootflow with a kasan kernel and kasan inline
>> instrumentation: all kasan configurations were tested on a large ubuntu
>> kernel with success with KASAN_KUNIT_TEST and KASAN_MODULE_TEST.
>>
>> [...]
>
> Applied, thanks!
>
> [1/6] riscv: Split early and final KASAN population functions
>       https://git.kernel.org/palmer/c/70a3bb1e1fd9
> [2/6] riscv: Rework kasan population functions
>       https://git.kernel.org/palmer/c/fec8e4f66e4d
> [3/6] riscv: Move DTB_EARLY_BASE_VA to the kernel address space
>       https://git.kernel.org/palmer/c/1cdf594686a3
> [4/6] riscv: Fix EFI stub usage of KASAN instrumented strcmp function
>       https://git.kernel.org/palmer/c/415e9a115124
> [5/6] riscv: Fix ptdump when KASAN is enabled
>       https://git.kernel.org/palmer/c/fe0c8624d20d
> [6/6] riscv: Unconditionnally select KASAN_VMALLOC if KASAN
>       https://git.kernel.org/palmer/c/4cdc06c5c741
>
> Best regards,

Sorry, this one didn't actually get tested -- I'd thought it was in the 
queue before I kicked off the run, but it wasn't.  It's testing now, 
I've dropped it from for-next for a bit as I don't remember if this is 
one of the patch sets that had a bulid/test failure.

Re: [PATCH v4 0/6] RISC-V kasan rework

[patchwork-bot+linux-riscv]

Hello:

This series was applied to riscv/linux.git (for-next)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Fri,  3 Feb 2023 08:52:26 +0100 you wrote:
> As described in patch 2, our current kasan implementation is intricate,
> so I tried to simplify the implementation and mimic what arm64/x86 are
> doing.
> 
> In addition it fixes UEFI bootflow with a kasan kernel and kasan inline
> instrumentation: all kasan configurations were tested on a large ubuntu
> kernel with success with KASAN_KUNIT_TEST and KASAN_MODULE_TEST.
> 
> [...]

Here is the summary with links:
  - [v4,1/6] riscv: Split early and final KASAN population functions
    https://git.kernel.org/riscv/c/70a3bb1e1fd9
  - [v4,2/6] riscv: Rework kasan population functions
    https://git.kernel.org/riscv/c/fec8e4f66e4d
  - [v4,3/6] riscv: Move DTB_EARLY_BASE_VA to the kernel address space
    https://git.kernel.org/riscv/c/1cdf594686a3
  - [v4,4/6] riscv: Fix EFI stub usage of KASAN instrumented strcmp function
    https://git.kernel.org/riscv/c/415e9a115124
  - [v4,5/6] riscv: Fix ptdump when KASAN is enabled
    https://git.kernel.org/riscv/c/fe0c8624d20d
  - [v4,6/6] riscv: Unconditionnally select KASAN_VMALLOC if KASAN
    https://git.kernel.org/riscv/c/4cdc06c5c741

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH v4 0/6] RISC-V kasan rework

[Palmer Dabbelt]

On Fri, 03 Feb 2023 08:52:26 +0100, Alexandre Ghiti wrote:
> As described in patch 2, our current kasan implementation is intricate,
> so I tried to simplify the implementation and mimic what arm64/x86 are
> doing.
> 
> In addition it fixes UEFI bootflow with a kasan kernel and kasan inline
> instrumentation: all kasan configurations were tested on a large ubuntu
> kernel with success with KASAN_KUNIT_TEST and KASAN_MODULE_TEST.
> 
> [...]

Applied, thanks!

[1/6] riscv: Split early and final KASAN population functions
      https://git.kernel.org/palmer/c/cd0334e1c091
[2/6] riscv: Rework kasan population functions
      https://git.kernel.org/palmer/c/96f9d4daf745
[3/6] riscv: Move DTB_EARLY_BASE_VA to the kernel address space
      https://git.kernel.org/palmer/c/401e84488800
[4/6] riscv: Fix EFI stub usage of KASAN instrumented strcmp function
      https://git.kernel.org/palmer/c/617955ca6e27
[5/6] riscv: Fix ptdump when KASAN is enabled
      https://git.kernel.org/palmer/c/ecd7ebaf0b5a
[6/6] riscv: Unconditionnally select KASAN_VMALLOC if KASAN
      https://git.kernel.org/palmer/c/864046c512c2

Best regards,
-- 
Palmer Dabbelt <palmer@rivosinc.com>

Re: [PATCH v4 0/6] RISC-V kasan rework

[Palmer Dabbelt]

On Fri, 03 Feb 2023 08:52:26 +0100, Alexandre Ghiti wrote:
> As described in patch 2, our current kasan implementation is intricate,
> so I tried to simplify the implementation and mimic what arm64/x86 are
> doing.
> 
> In addition it fixes UEFI bootflow with a kasan kernel and kasan inline
> instrumentation: all kasan configurations were tested on a large ubuntu
> kernel with success with KASAN_KUNIT_TEST and KASAN_MODULE_TEST.
> 
> [...]

Applied, thanks!

[1/6] riscv: Split early and final KASAN population functions
      https://git.kernel.org/palmer/c/cd0334e1c091
[2/6] riscv: Rework kasan population functions
      https://git.kernel.org/palmer/c/96f9d4daf745
[3/6] riscv: Move DTB_EARLY_BASE_VA to the kernel address space
      https://git.kernel.org/palmer/c/401e84488800
[4/6] riscv: Fix EFI stub usage of KASAN instrumented strcmp function
      https://git.kernel.org/palmer/c/617955ca6e27
[5/6] riscv: Fix ptdump when KASAN is enabled
      https://git.kernel.org/palmer/c/ecd7ebaf0b5a
[6/6] riscv: Unconditionnally select KASAN_VMALLOC if KASAN
      https://git.kernel.org/palmer/c/864046c512c2

Best regards,
-- 
Palmer Dabbelt <palmer@rivosinc.com>