In a couple of places there is a need to select whether read-only
protection of shadow pages is performed with PAGE_KERNEL_RO or with
PAGE_READONLY.
Add a helper to avoid duplicating the choice.
Signed-off-by: Christophe Leroy <[email protected]>
Cc: [email protected]
---
This small series applies on top of patch "powerpc/kasan: fix parallele
loading of modules" (https://patchwork.ozlabs.org/patch/1144757/).
Otherwise a manual merge has to be done (the modifications are
independant but close to each other in the file.)
---
arch/powerpc/mm/kasan/kasan_init_32.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
index 802387b231ad..e8ab3cc5f6e4 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -12,6 +12,14 @@
#include <asm/code-patching.h>
#include <mm/mmu_decl.h>
+static pgprot_t kasan_prot_ro(void)
+{
+ if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
+ return PAGE_READONLY;
+
+ return PAGE_KERNEL_RO;
+}
+
static void kasan_populate_pte(pte_t *ptep, pgprot_t prot)
{
unsigned long va = (unsigned long)kasan_early_shadow_page;
@@ -26,6 +34,7 @@ static int __ref kasan_init_shadow_page_tables(unsigned long k_start, unsigned l
{
pmd_t *pmd;
unsigned long k_cur, k_next;
+ pgprot_t prot = kasan_prot_ro();
pmd = pmd_offset(pud_offset(pgd_offset_k(k_start), k_start), k_start);
@@ -43,10 +52,7 @@ static int __ref kasan_init_shadow_page_tables(unsigned long k_start, unsigned l
if (!new)
return -ENOMEM;
- if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
- kasan_populate_pte(new, PAGE_READONLY);
- else
- kasan_populate_pte(new, PAGE_KERNEL_RO);
+ kasan_populate_pte(new, prot);
smp_wmb(); /* See comment in __pte_alloc */
@@ -103,10 +109,9 @@ static int __ref kasan_init_region(void *start, size_t size)
static void __init kasan_remap_early_shadow_ro(void)
{
- if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
- kasan_populate_pte(kasan_early_shadow_pte, PAGE_READONLY);
- else
- kasan_populate_pte(kasan_early_shadow_pte, PAGE_KERNEL_RO);
+ pgprot_t prot = kasan_prot_ro();
+
+ kasan_populate_pte(kasan_early_shadow_pte, prot);
flush_tlb_kernel_range(KASAN_SHADOW_START, KASAN_SHADOW_END);
}
--
2.13.3
Uncompressing Kernel Image ... OK
Loading Device Tree to 01ff7000, end 01fff74f ... OK
[ 0.000000] printk: bootconsole [udbg0] enabled
[ 0.000000] BUG: Unable to handle kernel data access at 0xf818c000
[ 0.000000] Faulting instruction address: 0xc0013c7c
[ 0.000000] Thread overran stack, or stack corrupted
[ 0.000000] Oops: Kernel access of bad area, sig: 11 [#1]
[ 0.000000] BE PAGE_SIZE=16K PREEMPT
[ 0.000000] Modules linked in:
[ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.3.0-rc4-s3k-dev-00743-g5abe4a3e8fd3-dirty #2080
[ 0.000000] NIP: c0013c7c LR: c0013310 CTR: 00000000
[ 0.000000] REGS: c0c5ff38 TRAP: 0300 Not tainted (5.3.0-rc4-s3k-dev-00743-g5abe4a3e8fd3-dirty)
[ 0.000000] MSR: 00001032 <ME,IR,DR,RI> CR: 99033955 XER: 80002100
[ 0.000000] DAR: f818c000 DSISR: 82000000
[ 0.000000] GPR00: c0013310 c0c5fff0 c0ad6ac0 c0c600c0 f818c031 82000000 00000000 ffffffff
[ 0.000000] GPR08: 00000000 f1f1f1f1 c0013c2c c0013304 99033955 00400008 00000000 07ff9598
[ 0.000000] GPR16: 00000000 07ffb94c 00000000 00000000 00000000 00000000 00000000 f818cfb2
[ 0.000000] GPR24: 00000000 00000000 00001000 ffffffff 00000000 c07dbf80 00000000 f818c000
[ 0.000000] NIP [c0013c7c] do_page_fault+0x50/0x904
[ 0.000000] LR [c0013310] handle_page_fault+0xc/0x38
[ 0.000000] Call Trace:
[ 0.000000] Instruction dump:
[ 0.000000] be010080 91410014 553fe8fe 3d40c001 3d20f1f1 7d800026 394a3c2c 3fffe000
[ 0.000000] 6129f1f1 900100c4 9181007c 91410018 <913f0000> 3d2001f4 6129f4f4 913f0004
Don't map the early shadow page read-only yet when creating the new
page tables for the real shadow memory, otherwise the memblock
allocations that immediately follows to create the real shadow pages
that are about to replace the early shadow page trigger a page fault
if they fall into the region being worked on at the moment.
Signed-off-by: Christophe Leroy <[email protected]>
Fixes: 2edb16efc899 ("powerpc/32: Add KASAN support")
Cc: [email protected]
---
arch/powerpc/mm/kasan/kasan_init_32.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
index e8ab3cc5f6e4..0e6ed4413eea 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -34,7 +34,7 @@ static int __ref kasan_init_shadow_page_tables(unsigned long k_start, unsigned l
{
pmd_t *pmd;
unsigned long k_cur, k_next;
- pgprot_t prot = kasan_prot_ro();
+ pgprot_t prot = slab_is_available() ? kasan_prot_ro() : PAGE_KERNEL;
pmd = pmd_offset(pud_offset(pgd_offset_k(k_start), k_start), k_start);
@@ -110,9 +110,22 @@ static int __ref kasan_init_region(void *start, size_t size)
static void __init kasan_remap_early_shadow_ro(void)
{
pgprot_t prot = kasan_prot_ro();
+ unsigned long k_start = KASAN_SHADOW_START;
+ unsigned long k_end = KASAN_SHADOW_END;
+ unsigned long k_cur;
+ phys_addr_t pa = __pa(kasan_early_shadow_page);
kasan_populate_pte(kasan_early_shadow_pte, prot);
+ for (k_cur = k_start & PAGE_MASK; k_cur < k_end; k_cur += PAGE_SIZE) {
+ pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
+ pte_t *ptep = pte_offset_kernel(pmd, k_cur);
+
+ if ((pte_val(*ptep) & PTE_RPN_MASK) != pa)
+ continue;
+
+ __set_pte_at(&init_mm, k_cur, ptep, pfn_pte(PHYS_PFN(pa), prot), 0);
+ }
flush_tlb_kernel_range(KASAN_SHADOW_START, KASAN_SHADOW_END);
}
--
2.13.3
On Wed, 2019-08-21 at 10:20:00 UTC, Christophe Leroy wrote:
> In a couple of places there is a need to select whether read-only
> protection of shadow pages is performed with PAGE_KERNEL_RO or with
> PAGE_READONLY.
>
> Add a helper to avoid duplicating the choice.
>
> Signed-off-by: Christophe Leroy <[email protected]>
> Cc: [email protected]
Series applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/4c0f5d1eb4072871c34530358df45f05ab80edd6
cheers