This patchset supports Kfence feature, tested the kfence_test on ARM QEMU
with or without ARM_LPAE and all passed.
V2:
- drop patch4 in v1, which is used a new way to skip kfence test
see commit c40c6e593bf9 ("kfence: test: fail fast if disabled at boot")
- fix some issue about NO MMU
- drop useless set_memory_valid() under no mmu
- fix implicit declaration of function ‘is_write_fault’ if no mmu
- make KFENCE depends on !XIP_KERNEL, no tested with xip
v1:
https://lore.kernel.org/linux-arm-kernel/[email protected]/
Kefeng Wang (3):
ARM: mm: Provide set_memory_valid()
ARM: mm: Provide is_write_fault()
ARM: Support KFENCE for ARM
arch/arm/Kconfig | 1 +
arch/arm/include/asm/kfence.h | 53 +++++++++++++++++++++++++++++++
arch/arm/include/asm/set_memory.h | 1 +
arch/arm/mm/fault.c | 16 ++++++++--
arch/arm/mm/pageattr.c | 42 ++++++++++++++++++------
5 files changed, 100 insertions(+), 13 deletions(-)
create mode 100644 arch/arm/include/asm/kfence.h
--
2.26.2
This function validates and invalidates PTE entries, it will be used
in the later patch.
Signed-off-by: Kefeng Wang <[email protected]>
---
arch/arm/include/asm/set_memory.h | 1 +
arch/arm/mm/pageattr.c | 42 +++++++++++++++++++++++--------
2 files changed, 33 insertions(+), 10 deletions(-)
diff --git a/arch/arm/include/asm/set_memory.h b/arch/arm/include/asm/set_memory.h
index ec17fc0fda7a..0211b9c5b14d 100644
--- a/arch/arm/include/asm/set_memory.h
+++ b/arch/arm/include/asm/set_memory.h
@@ -11,6 +11,7 @@ int set_memory_ro(unsigned long addr, int numpages);
int set_memory_rw(unsigned long addr, int numpages);
int set_memory_x(unsigned long addr, int numpages);
int set_memory_nx(unsigned long addr, int numpages);
+int set_memory_valid(unsigned long addr, int numpages, int enable);
#else
static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; }
static inline int set_memory_rw(unsigned long addr, int numpages) { return 0; }
diff --git a/arch/arm/mm/pageattr.c b/arch/arm/mm/pageattr.c
index 9790ae3a8c68..c3c34fe714b0 100644
--- a/arch/arm/mm/pageattr.c
+++ b/arch/arm/mm/pageattr.c
@@ -32,14 +32,31 @@ static bool in_range(unsigned long start, unsigned long size,
size <= range_end - start;
}
+/*
+ * This function assumes that the range is mapped with PAGE_SIZE pages.
+ */
+static int __change_memory_common(unsigned long start, unsigned long size,
+ pgprot_t set_mask, pgprot_t clear_mask)
+{
+ struct page_change_data data;
+ int ret;
+
+ data.set_mask = set_mask;
+ data.clear_mask = clear_mask;
+
+ ret = apply_to_page_range(&init_mm, start, size, change_page_range,
+ &data);
+
+ flush_tlb_kernel_range(start, start + size);
+ return ret;
+}
+
static int change_memory_common(unsigned long addr, int numpages,
pgprot_t set_mask, pgprot_t clear_mask)
{
unsigned long start = addr & PAGE_MASK;
unsigned long end = PAGE_ALIGN(addr) + numpages * PAGE_SIZE;
unsigned long size = end - start;
- int ret;
- struct page_change_data data;
WARN_ON_ONCE(start != addr);
@@ -50,14 +67,7 @@ static int change_memory_common(unsigned long addr, int numpages,
!in_range(start, size, VMALLOC_START, VMALLOC_END))
return -EINVAL;
- data.set_mask = set_mask;
- data.clear_mask = clear_mask;
-
- ret = apply_to_page_range(&init_mm, start, size, change_page_range,
- &data);
-
- flush_tlb_kernel_range(start, end);
- return ret;
+ return __change_memory_common(start, size, set_mask, clear_mask);
}
int set_memory_ro(unsigned long addr, int numpages)
@@ -87,3 +97,15 @@ int set_memory_x(unsigned long addr, int numpages)
__pgprot(0),
__pgprot(L_PTE_XN));
}
+
+int set_memory_valid(unsigned long addr, int numpages, int enable)
+{
+ if (enable)
+ return __change_memory_common(addr, PAGE_SIZE * numpages,
+ __pgprot(L_PTE_VALID),
+ __pgprot(0));
+ else
+ return __change_memory_common(addr, PAGE_SIZE * numpages,
+ __pgprot(0),
+ __pgprot(L_PTE_VALID));
+}
--
2.26.2
The function will check whether the fault is caused by a write access.
Signed-off-by: Kefeng Wang <[email protected]>
---
arch/arm/mm/fault.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index bc8779d54a64..f7ab6dabe89f 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -207,6 +207,11 @@ static inline bool is_permission_fault(unsigned int fsr)
return false;
}
+static inline bool is_write_fault(unsigned int fsr)
+{
+ return (fsr & FSR_WRITE) && !(fsr & FSR_CM);
+}
+
static vm_fault_t __kprobes
__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int flags,
unsigned long vma_flags, struct pt_regs *regs)
@@ -261,7 +266,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
- if ((fsr & FSR_WRITE) && !(fsr & FSR_CM)) {
+ if (is_write_fault(fsr)) {
flags |= FAULT_FLAG_WRITE;
vm_flags = VM_WRITE;
}
--
2.26.2
Add architecture specific implementation details for KFENCE and enable
KFENCE on ARM. In particular, this implements the required interface in
<asm/kfence.h>.
KFENCE requires that attributes for pages from its memory pool can
individually be set. Therefore, force the kfence pool to be mapped
at page granularity.
Testing this patch using the testcases in kfence_test.c and all passed
with or without ARM_LPAE.
Signed-off-by: Kefeng Wang <[email protected]>
---
arch/arm/Kconfig | 1 +
arch/arm/include/asm/kfence.h | 53 +++++++++++++++++++++++++++++++++++
arch/arm/mm/fault.c | 19 ++++++++-----
3 files changed, 66 insertions(+), 7 deletions(-)
create mode 100644 arch/arm/include/asm/kfence.h
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index b9f72337224c..6d1f6f48995c 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -69,6 +69,7 @@ config ARM
select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
+ select HAVE_ARCH_KFENCE if MMU && !XIP_KERNEL
select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
select HAVE_ARCH_MMAP_RND_BITS if MMU
diff --git a/arch/arm/include/asm/kfence.h b/arch/arm/include/asm/kfence.h
new file mode 100644
index 000000000000..7980d0f2271f
--- /dev/null
+++ b/arch/arm/include/asm/kfence.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_ARM_KFENCE_H
+#define __ASM_ARM_KFENCE_H
+
+#include <linux/kfence.h>
+
+#include <asm/pgalloc.h>
+#include <asm/set_memory.h>
+
+static inline int split_pmd_page(pmd_t *pmd, unsigned long addr)
+{
+ int i;
+ unsigned long pfn = PFN_DOWN(__pa(addr));
+ pte_t *pte = pte_alloc_one_kernel(&init_mm);
+
+ if (!pte)
+ return -ENOMEM;
+
+ for (i = 0; i < PTRS_PER_PTE; i++)
+ set_pte_ext(pte + i, pfn_pte(pfn + i, PAGE_KERNEL), 0);
+ pmd_populate_kernel(&init_mm, pmd, pte);
+
+ flush_tlb_kernel_range(addr, addr + PMD_SIZE);
+ return 0;
+}
+
+static inline bool arch_kfence_init_pool(void)
+{
+ unsigned long addr;
+ pmd_t *pmd;
+
+ for (addr = (unsigned long)__kfence_pool; is_kfence_address((void *)addr);
+ addr += PAGE_SIZE) {
+ pmd = pmd_off_k(addr);
+
+ if (pmd_leaf(*pmd)) {
+ if (split_pmd_page(pmd, addr & PMD_MASK))
+ return false;
+ }
+ }
+
+ return true;
+}
+
+static inline bool kfence_protect_page(unsigned long addr, bool protect)
+{
+ set_memory_valid(addr, 1, !protect);
+
+ return true;
+}
+
+#endif /* __ASM_ARM_KFENCE_H */
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index f7ab6dabe89f..49148b675b43 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -17,6 +17,7 @@
#include <linux/sched/debug.h>
#include <linux/highmem.h>
#include <linux/perf_event.h>
+#include <linux/kfence.h>
#include <asm/system_misc.h>
#include <asm/system_info.h>
@@ -99,6 +100,11 @@ void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
{ }
#endif /* CONFIG_MMU */
+static inline bool is_write_fault(unsigned int fsr)
+{
+ return (fsr & FSR_WRITE) && !(fsr & FSR_CM);
+}
+
static void die_kernel_fault(const char *msg, struct mm_struct *mm,
unsigned long addr, unsigned int fsr,
struct pt_regs *regs)
@@ -131,10 +137,14 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
/*
* No handler, we'll have to terminate things with extreme prejudice.
*/
- if (addr < PAGE_SIZE)
+ if (addr < PAGE_SIZE) {
msg = "NULL pointer dereference";
- else
+ } else {
+ if (kfence_handle_page_fault(addr, is_write_fault(fsr), regs))
+ return;
+
msg = "paging request";
+ }
die_kernel_fault(msg, mm, addr, fsr, regs);
}
@@ -207,11 +217,6 @@ static inline bool is_permission_fault(unsigned int fsr)
return false;
}
-static inline bool is_write_fault(unsigned int fsr)
-{
- return (fsr & FSR_WRITE) && !(fsr & FSR_CM);
-}
-
static vm_fault_t __kprobes
__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int flags,
unsigned long vma_flags, struct pt_regs *regs)
--
2.26.2
On Wed, Nov 3, 2021 at 2:26 PM Kefeng Wang <[email protected]> wrote:
>
> Add architecture specific implementation details for KFENCE and enable
> KFENCE on ARM. In particular, this implements the required interface in
> <asm/kfence.h>.
>
> KFENCE requires that attributes for pages from its memory pool can
> individually be set. Therefore, force the kfence pool to be mapped
> at page granularity.
>
> Testing this patch using the testcases in kfence_test.c and all passed
> with or without ARM_LPAE.
>
> Signed-off-by: Kefeng Wang <[email protected]>
> ---
> arch/arm/Kconfig | 1 +
> arch/arm/include/asm/kfence.h | 53 +++++++++++++++++++++++++++++++++++
> arch/arm/mm/fault.c | 19 ++++++++-----
> 3 files changed, 66 insertions(+), 7 deletions(-)
> create mode 100644 arch/arm/include/asm/kfence.h
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index b9f72337224c..6d1f6f48995c 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -69,6 +69,7 @@ config ARM
> select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
> select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
> select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
> + select HAVE_ARCH_KFENCE if MMU && !XIP_KERNEL
> select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
> select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
> select HAVE_ARCH_MMAP_RND_BITS if MMU
> diff --git a/arch/arm/include/asm/kfence.h b/arch/arm/include/asm/kfence.h
> new file mode 100644
> index 000000000000..7980d0f2271f
> --- /dev/null
> +++ b/arch/arm/include/asm/kfence.h
> @@ -0,0 +1,53 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef __ASM_ARM_KFENCE_H
> +#define __ASM_ARM_KFENCE_H
> +
> +#include <linux/kfence.h>
> +
> +#include <asm/pgalloc.h>
> +#include <asm/set_memory.h>
> +
> +static inline int split_pmd_page(pmd_t *pmd, unsigned long addr)
> +{
> + int i;
> + unsigned long pfn = PFN_DOWN(__pa(addr));
> + pte_t *pte = pte_alloc_one_kernel(&init_mm);
> +
> + if (!pte)
> + return -ENOMEM;
> +
> + for (i = 0; i < PTRS_PER_PTE; i++)
> + set_pte_ext(pte + i, pfn_pte(pfn + i, PAGE_KERNEL), 0);
> + pmd_populate_kernel(&init_mm, pmd, pte);
> +
> + flush_tlb_kernel_range(addr, addr + PMD_SIZE);
> + return 0;
> +}
> +
> +static inline bool arch_kfence_init_pool(void)
> +{
> + unsigned long addr;
> + pmd_t *pmd;
> +
> + for (addr = (unsigned long)__kfence_pool; is_kfence_address((void *)addr);
> + addr += PAGE_SIZE) {
> + pmd = pmd_off_k(addr);
> +
> + if (pmd_leaf(*pmd)) {
> + if (split_pmd_page(pmd, addr & PMD_MASK))
> + return false;
> + }
> + }
> +
> + return true;
> +}
> +
> +static inline bool kfence_protect_page(unsigned long addr, bool protect)
> +{
> + set_memory_valid(addr, 1, !protect);
> +
> + return true;
> +}
> +
> +#endif /* __ASM_ARM_KFENCE_H */
> diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
> index f7ab6dabe89f..49148b675b43 100644
> --- a/arch/arm/mm/fault.c
> +++ b/arch/arm/mm/fault.c
> @@ -17,6 +17,7 @@
> #include <linux/sched/debug.h>
> #include <linux/highmem.h>
> #include <linux/perf_event.h>
> +#include <linux/kfence.h>
>
> #include <asm/system_misc.h>
> #include <asm/system_info.h>
> @@ -99,6 +100,11 @@ void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
> { }
> #endif /* CONFIG_MMU */
>
> +static inline bool is_write_fault(unsigned int fsr)
> +{
> + return (fsr & FSR_WRITE) && !(fsr & FSR_CM);
> +}
Please don't increase the diff by moving the code around. Consider
putting is_write_fault() in the right place in "ARM: mm: Provide
is_write_fault()" instead.
On 2021/11/4 0:22, Alexander Potapenko wrote:
> On Wed, Nov 3, 2021 at 2:26 PM Kefeng Wang <[email protected]> wrote:
>>
>> Add architecture specific implementation details for KFENCE and enable
>> KFENCE on ARM. In particular, this implements the required interface in
>> <asm/kfence.h>.
>>
>> KFENCE requires that attributes for pages from its memory pool can
>> individually be set. Therefore, force the kfence pool to be mapped
>> at page granularity.
>>
>> Testing this patch using the testcases in kfence_test.c and all passed
>> with or without ARM_LPAE.
>>
>> Signed-off-by: Kefeng Wang <[email protected]>
...
>> diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
>> index f7ab6dabe89f..49148b675b43 100644
>> --- a/arch/arm/mm/fault.c
>> +++ b/arch/arm/mm/fault.c
>> @@ -17,6 +17,7 @@
>> #include <linux/sched/debug.h>
>> #include <linux/highmem.h>
>> #include <linux/perf_event.h>
>> +#include <linux/kfence.h>
>>
>> #include <asm/system_misc.h>
>> #include <asm/system_info.h>
>> @@ -99,6 +100,11 @@ void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
>> { }
>> #endif /* CONFIG_MMU */
>>
>> +static inline bool is_write_fault(unsigned int fsr)
>> +{
>> + return (fsr & FSR_WRITE) && !(fsr & FSR_CM);
>> +}
>
> Please don't increase the diff by moving the code around. Consider
> putting is_write_fault() in the right place in "ARM: mm: Provide
> is_write_fault()" instead.
Sure. Let's wait some time to see whether there are any other comments,
and resend, thanks.
> .
>
On Wed, 3 Nov 2021 at 14:26, Kefeng Wang <[email protected]> wrote:
>
> This patchset supports Kfence feature, tested the kfence_test on ARM QEMU
> with or without ARM_LPAE and all passed.
>
> V2:
> - drop patch4 in v1, which is used a new way to skip kfence test
> see commit c40c6e593bf9 ("kfence: test: fail fast if disabled at boot")
> - fix some issue about NO MMU
> - drop useless set_memory_valid() under no mmu
> - fix implicit declaration of function ‘is_write_fault’ if no mmu
> - make KFENCE depends on !XIP_KERNEL, no tested with xip
>
> v1:
> https://lore.kernel.org/linux-arm-kernel/[email protected]/
>
> Kefeng Wang (3):
> ARM: mm: Provide set_memory_valid()
> ARM: mm: Provide is_write_fault()
> ARM: Support KFENCE for ARM
Looks good to me.
Acked-by: Marco Elver <[email protected]>
> arch/arm/Kconfig | 1 +
> arch/arm/include/asm/kfence.h | 53 +++++++++++++++++++++++++++++++
> arch/arm/include/asm/set_memory.h | 1 +
> arch/arm/mm/fault.c | 16 ++++++++--
> arch/arm/mm/pageattr.c | 42 ++++++++++++++++++------
> 5 files changed, 100 insertions(+), 13 deletions(-)
> create mode 100644 arch/arm/include/asm/kfence.h
>
> --
> 2.26.2
>
On 2021/11/4 15:00, Marco Elver wrote:
> On Wed, 3 Nov 2021 at 14:26, Kefeng Wang <[email protected]> wrote:
>>
>> This patchset supports Kfence feature, tested the kfence_test on ARM QEMU
>> with or without ARM_LPAE and all passed.
>>
>> V2:
>> - drop patch4 in v1, which is used a new way to skip kfence test
>> see commit c40c6e593bf9 ("kfence: test: fail fast if disabled at boot")
>> - fix some issue about NO MMU
>> - drop useless set_memory_valid() under no mmu
>> - fix implicit declaration of function ‘is_write_fault’ if no mmu
>> - make KFENCE depends on !XIP_KERNEL, no tested with xip
>>
>> v1:
>> https://lore.kernel.org/linux-arm-kernel/[email protected]/
>>
>> Kefeng Wang (3):
>> ARM: mm: Provide set_memory_valid()
>> ARM: mm: Provide is_write_fault()
>> ARM: Support KFENCE for ARM
>
> Looks good to me.
>
> Acked-by: Marco Elver <[email protected]>
Thanks Marco.
The ARM tree is closed; we're in the mainline merge window. Please
resend after -rc1 is released.
On Wed, Nov 03, 2021 at 09:38:42PM +0800, Kefeng Wang wrote:
> This patchset supports Kfence feature, tested the kfence_test on ARM QEMU
> with or without ARM_LPAE and all passed.
>
> V2:
> - drop patch4 in v1, which is used a new way to skip kfence test
> see commit c40c6e593bf9 ("kfence: test: fail fast if disabled at boot")
> - fix some issue about NO MMU
> - drop useless set_memory_valid() under no mmu
> - fix implicit declaration of function ‘is_write_fault’ if no mmu
> - make KFENCE depends on !XIP_KERNEL, no tested with xip
>
> v1:
> https://lore.kernel.org/linux-arm-kernel/[email protected]/
>
> Kefeng Wang (3):
> ARM: mm: Provide set_memory_valid()
> ARM: mm: Provide is_write_fault()
> ARM: Support KFENCE for ARM
>
> arch/arm/Kconfig | 1 +
> arch/arm/include/asm/kfence.h | 53 +++++++++++++++++++++++++++++++
> arch/arm/include/asm/set_memory.h | 1 +
> arch/arm/mm/fault.c | 16 ++++++++--
> arch/arm/mm/pageattr.c | 42 ++++++++++++++++++------
> 5 files changed, 100 insertions(+), 13 deletions(-)
> create mode 100644 arch/arm/include/asm/kfence.h
>
> --
> 2.26.2
>
>
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
On 2021/11/4 20:12, Russell King (Oracle) wrote:
> The ARM tree is closed; we're in the mainline merge window. Please
> resend after -rc1 is released.
Got it, will do.
>
> On Wed, Nov 03, 2021 at 09:38:42PM +0800, Kefeng Wang wrote:
>> This patchset supports Kfence feature, tested the kfence_test on ARM QEMU
>> with or without ARM_LPAE and all passed.
>>
>> V2:
>> - drop patch4 in v1, which is used a new way to skip kfence test
>> see commit c40c6e593bf9 ("kfence: test: fail fast if disabled at boot")
>> - fix some issue about NO MMU
>> - drop useless set_memory_valid() under no mmu
>> - fix implicit declaration of function ‘is_write_fault’ if no mmu
>> - make KFENCE depends on !XIP_KERNEL, no tested with xip
>>
>> v1:
>> https://lore.kernel.org/linux-arm-kernel/[email protected]/
>>
>> Kefeng Wang (3):
>> ARM: mm: Provide set_memory_valid()
>> ARM: mm: Provide is_write_fault()
>> ARM: Support KFENCE for ARM
>>
>> arch/arm/Kconfig | 1 +
>> arch/arm/include/asm/kfence.h | 53 +++++++++++++++++++++++++++++++
>> arch/arm/include/asm/set_memory.h | 1 +
>> arch/arm/mm/fault.c | 16 ++++++++--
>> arch/arm/mm/pageattr.c | 42 ++++++++++++++++++------
>> 5 files changed, 100 insertions(+), 13 deletions(-)
>> create mode 100644 arch/arm/include/asm/kfence.h
>>
>> --
>> 2.26.2
>>
>>
>