[PATCH 0/4 v3] Add KFENCE support for LoongArch

[PATCH 0/4 v3] Add KFENCE support for LoongArch

[Enze Li]

Hi all,

This patchset adds KFENCE support on LoongArch.

To run the testcases, you will need to enable the following options,

-> Kernel hacking
   [*] Tracers
       [*] Support for tracing block IO actions (NEW)
   -> Kernel Testing and Coverage
      <*> KUnit - Enable support for unit tests

and then,

-> Kernel hacking
   -> Memory Debugging
      [*] KFENCE: low-overhead sampling-based memory safety error detector (NEW)
          <*> KFENCE integration test suite (NEW)

With these options enabled, KFENCE will be tested during kernel startup.
And normally, you might get the following feedback,

========================================================
[   35.326363 ] # kfence: pass:23 fail:0 skip:2 total:25
[   35.326486 ] # Totals: pass:23 fail:0 skip:2 total:25
[   35.326621 ] ok 1 kfence
========================================================

you might notice that 2 testcases have been skipped.  If you tend to run
all testcases, please enable CONFIG_INIT_ON_FREE_DEFAULT_ON, you can
find it here,

-> Security options
   -> Kernel hardening options
      -> Memory initialization
         [*] Enable heap memory zeroing on free by default

and you might get all testcases passed.
========================================================
[   35.531860 ] # kfence: pass:25 fail:0 skip:0 total:25
[   35.531999 ] # Totals: pass:25 fail:0 skip:0 total:25
[   35.532135 ] ok 1 kfence
========================================================

v3:
   * Address Huacai's comments.
   * Fix a bug that Jackie Liu pointed out.
   * Rewrite arch_stack_walk() with the suggestion of Jinyang He.

v2:
   * Address Huacai's comments.
   * Fix typos in commit message.

Thanks,
Enze

Enze Li (4):
  KFENCE: Defer the assignment of the local variable addr
  LoongArch: mm: Add page table mapped mode support
  LoongArch: Get stack without NMI when providing regs parameter
  LoongArch: Add KFENCE support

 arch/loongarch/Kconfig               |  1 +
 arch/loongarch/include/asm/kfence.h  | 66 ++++++++++++++++++++++++++++
 arch/loongarch/include/asm/page.h    |  8 +++-
 arch/loongarch/include/asm/pgtable.h | 16 ++++++-
 arch/loongarch/kernel/stacktrace.c   | 18 ++++----
 arch/loongarch/mm/fault.c            | 22 ++++++----
 arch/loongarch/mm/pgtable.c          |  7 +++
 mm/kfence/core.c                     |  5 ++-
 8 files changed, 123 insertions(+), 20 deletions(-)
 create mode 100644 arch/loongarch/include/asm/kfence.h

-- 
2.34.1

[PATCH 1/4 v3] KFENCE: Defer the assignment of the local variable addr

[Enze Li]

The LoongArch architecture is different from other architectures.
It needs to update __kfence_pool during arch_kfence_init_pool().

This patch modifies the assignment location of the local variable addr
in the kfence_init_pool function to support the case of updating
__kfence_pool in arch_kfence_init_pool().

Signed-off-by: Enze Li <lienze@kylinos.cn>
Acked-by: Marco Elver <elver@google.com>
---
 mm/kfence/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index dad3c0eb70a0..e124ffff489f 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -566,13 +566,14 @@ static void rcu_guarded_free(struct rcu_head *h)
  */
 static unsigned long kfence_init_pool(void)
 {
-	unsigned long addr = (unsigned long)__kfence_pool;
+	unsigned long addr;
 	struct page *pages;
 	int i;
 
 	if (!arch_kfence_init_pool())
-		return addr;
+		return (unsigned long)__kfence_pool;
 
+	addr = (unsigned long)__kfence_pool;
 	pages = virt_to_page(__kfence_pool);
 
 	/*
-- 
2.34.1

[PATCH 2/4 v3] LoongArch: mm: Add page table mapped mode support

[Enze Li]

According to LoongArch documentation online, there are two types of address
translation modes: direct mapped address translation mode (direct mapped mode)
and page table mapped address translation mode (page table mapped mode).

Currently, the upstream kernel only supports direct mapped mode.
This patch adds a function that determines whether page table mapped
mode should be used, and also adds the corresponding handler functions
for both modes.

For more details on the two modes, see [1].

[1] https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#virtual-address-space-and-address-translation-mode

Signed-off-by: Enze Li <lienze@kylinos.cn>
---
 arch/loongarch/include/asm/page.h    | 8 +++++++-
 arch/loongarch/include/asm/pgtable.h | 3 +++
 arch/loongarch/mm/pgtable.c          | 7 +++++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/loongarch/include/asm/page.h b/arch/loongarch/include/asm/page.h
index 26e8dccb6619..a256fd6cb7bb 100644
--- a/arch/loongarch/include/asm/page.h
+++ b/arch/loongarch/include/asm/page.h
@@ -84,7 +84,13 @@ typedef struct { unsigned long pgprot; } pgprot_t;
 #define sym_to_pfn(x)		__phys_to_pfn(__pa_symbol(x))
 
 #define virt_to_pfn(kaddr)	PFN_DOWN(PHYSADDR(kaddr))
-#define virt_to_page(kaddr)	pfn_to_page(virt_to_pfn(kaddr))
+
+#define virt_to_page(kaddr)						\
+({									\
+	((unsigned long)kaddr >= vm_map_base) ?				\
+	tlb_virt_to_page((unsigned long)kaddr) :			\
+	dmw_virt_to_page((unsigned long)kaddr);				\
+})
 
 extern int __virt_addr_valid(volatile void *kaddr);
 #define virt_addr_valid(kaddr)	__virt_addr_valid((volatile void *)(kaddr))
diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
index 38afeb7dd58b..716a7fcab15e 100644
--- a/arch/loongarch/include/asm/pgtable.h
+++ b/arch/loongarch/include/asm/pgtable.h
@@ -353,6 +353,9 @@ static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *pt
 #define PMD_T_LOG2	(__builtin_ffs(sizeof(pmd_t)) - 1)
 #define PTE_T_LOG2	(__builtin_ffs(sizeof(pte_t)) - 1)
 
+inline struct page *tlb_virt_to_page(unsigned long kaddr);
+#define dmw_virt_to_page(kaddr)	pfn_to_page(virt_to_pfn(kaddr))
+
 extern pgd_t swapper_pg_dir[];
 extern pgd_t invalid_pg_dir[];
 
diff --git a/arch/loongarch/mm/pgtable.c b/arch/loongarch/mm/pgtable.c
index 36a6dc0148ae..fea8fd2cf141 100644
--- a/arch/loongarch/mm/pgtable.c
+++ b/arch/loongarch/mm/pgtable.c
@@ -9,6 +9,13 @@
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 
+
+inline struct page *tlb_virt_to_page(unsigned long kaddr)
+{
+	return pte_page(*virt_to_kpte(kaddr));
+}
+EXPORT_SYMBOL_GPL(tlb_virt_to_page);
+
 pgd_t *pgd_alloc(struct mm_struct *mm)
 {
 	pgd_t *ret, *init;
-- 
2.34.1

[PATCH 3/4 v3] LoongArch: Get stack without NMI when providing regs parameter

[Enze Li]

Currently, arch_stack_walk() can only get the full stack information
including NMI.  This is because the implementation of arch_stack_walk()
is forced to ignore the information passed by the regs parameter and use
the current stack information instead.

For some detection systems like KFENCE, only partial stack information
is needed.  In particular, the stack frame where the interrupt occurred.

To support KFENCE, this patch modifies the implementation of the
arch_stack_walk() function so that if this function is called with the
regs argument passed, it retains all the stack information in regs and
uses it to provide accurate information.

Before the patch applied, I get,
[    1.531195 ] ==================================================================
[    1.531442 ] BUG: KFENCE: out-of-bounds read in stack_trace_save_regs+0x48/0x6c
[    1.531442 ]
[    1.531900 ] Out-of-bounds read at 0xffff800012267fff (1B left of kfence-#12):
[    1.532046 ]  stack_trace_save_regs+0x48/0x6c
[    1.532169 ]  kfence_report_error+0xa4/0x528
[    1.532276 ]  kfence_handle_page_fault+0x124/0x270
[    1.532388 ]  no_context+0x50/0x94
[    1.532453 ]  do_page_fault+0x1a8/0x36c
[    1.532524 ]  tlb_do_page_fault_0+0x118/0x1b4
[    1.532623 ]  test_out_of_bounds_read+0xa0/0x1d8
[    1.532745 ]  kunit_generic_run_threadfn_adapter+0x1c/0x28
[    1.532854 ]  kthread+0x124/0x130
[    1.532922 ]  ret_from_kernel_thread+0xc/0xa4
<snip>

With this patch applied, I get the correct stack information.
[    1.320220 ] ==================================================================
[    1.320401 ] BUG: KFENCE: out-of-bounds read in test_out_of_bounds_read+0xa8/0x1d8
[    1.320401 ]
[    1.320898 ] Out-of-bounds read at 0xffff800012257fff (1B left of kfence-#10):
[    1.321134 ]  test_out_of_bounds_read+0xa8/0x1d8
[    1.321264 ]  kunit_generic_run_threadfn_adapter+0x1c/0x28
[    1.321392 ]  kthread+0x124/0x130
[    1.321459 ]  ret_from_kernel_thread+0xc/0xa4
<snip>

Co-authored-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Enze Li <lienze@kylinos.cn>
---
 arch/loongarch/kernel/stacktrace.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/loongarch/kernel/stacktrace.c b/arch/loongarch/kernel/stacktrace.c
index 2463d2fea21f..92270f14db94 100644
--- a/arch/loongarch/kernel/stacktrace.c
+++ b/arch/loongarch/kernel/stacktrace.c
@@ -18,17 +18,19 @@ void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 	struct pt_regs dummyregs;
 	struct unwind_state state;
 
-	regs = &dummyregs;
+	if (!regs) {
+		regs = &dummyregs;
 
-	if (task == current) {
-		regs->regs[3] = (unsigned long)__builtin_frame_address(0);
-		regs->csr_era = (unsigned long)__builtin_return_address(0);
-	} else {
-		regs->regs[3] = thread_saved_fp(task);
-		regs->csr_era = thread_saved_ra(task);
+		if (task == current) {
+			regs->regs[3] = (unsigned long)__builtin_frame_address(0);
+			regs->csr_era = (unsigned long)__builtin_return_address(0);
+		} else {
+			regs->regs[3] = thread_saved_fp(task);
+			regs->csr_era = thread_saved_ra(task);
+		}
+		regs->regs[1] = 0;
 	}
 
-	regs->regs[1] = 0;
 	for (unwind_start(&state, task, regs);
 	     !unwind_done(&state) && !unwind_error(&state); unwind_next_frame(&state)) {
 		addr = unwind_get_return_address(&state);
-- 
2.34.1

[PATCH 4/4 v3] LoongArch: Add KFENCE support

[Enze Li]

The LoongArch architecture is quite different from other architectures.
When the allocating of KFENCE itself is done, it is mapped to the direct
mapping configuration window [1] by default on LoongArch.  It means that
it is not possible to use the page table mapped mode which required by
the KFENCE system and therefore it should be remapped to the appropriate
region.

This patch adds architecture specific implementation details for KFENCE.
In particular, this implements the required interface in <asm/kfence.h>.

Tested this patch by running the testcases and all passed.

[1] https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#virtual-address-space-and-address-translation-mode

Signed-off-by: Enze Li <lienze@kylinos.cn>
---
 arch/loongarch/Kconfig               |  1 +
 arch/loongarch/include/asm/kfence.h  | 66 ++++++++++++++++++++++++++++
 arch/loongarch/include/asm/pgtable.h | 13 +++++-
 arch/loongarch/mm/fault.c            | 22 ++++++----
 4 files changed, 93 insertions(+), 9 deletions(-)
 create mode 100644 arch/loongarch/include/asm/kfence.h

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 5dbeb9b49ff7..b85ea4bf4a75 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -92,6 +92,7 @@ config LOONGARCH
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_JUMP_LABEL_RELATIVE
+	select HAVE_ARCH_KFENCE
 	select HAVE_ARCH_MMAP_RND_BITS if MMU
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_TRACEHOOK
diff --git a/arch/loongarch/include/asm/kfence.h b/arch/loongarch/include/asm/kfence.h
new file mode 100644
index 000000000000..d7db78a94b0f
--- /dev/null
+++ b/arch/loongarch/include/asm/kfence.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KFENCE support for LoongArch.
+ *
+ * Author: Enze Li <lienze@kylinos.cn>
+ * Copyright (C) 2022-2023 KylinSoft Corporation.
+ */
+
+#ifndef _ASM_LOONGARCH_KFENCE_H
+#define _ASM_LOONGARCH_KFENCE_H
+
+#include <linux/kfence.h>
+#include <asm/pgtable.h>
+#include <asm/tlb.h>
+
+static inline bool arch_kfence_init_pool(void)
+{
+	char *kfence_pool = __kfence_pool;
+	struct vm_struct *area;
+	int err;
+
+	area = __get_vm_area_caller(KFENCE_POOL_SIZE, VM_IOREMAP,
+				    KFENCE_AREA_START, KFENCE_AREA_END,
+				    __builtin_return_address(0));
+	if (!area)
+		return false;
+
+	__kfence_pool = (char *)area->addr;
+	err = ioremap_page_range((unsigned long)__kfence_pool,
+				 (unsigned long)__kfence_pool + KFENCE_POOL_SIZE,
+				 virt_to_phys((void *)kfence_pool),
+				 PAGE_KERNEL);
+	if (err) {
+		free_vm_area(area);
+		/*
+		 * If ioremap_page_range() failed, we have to restore
+		 * __kfence_pool to ensure that it can still free the
+		 * memblock allocated memory.
+		 */
+		__kfence_pool = kfence_pool;
+		return false;
+	}
+
+	return true;
+}
+
+/* Protect the given page and flush TLB. */
+static inline bool kfence_protect_page(unsigned long addr, bool protect)
+{
+	pte_t *pte = virt_to_kpte(addr);
+
+	if (WARN_ON(!pte) || pte_none(*pte))
+		return false;
+
+	if (protect)
+		set_pte(pte, __pte(pte_val(*pte) & ~(_PAGE_VALID | _PAGE_PRESENT)));
+	else
+		set_pte(pte, __pte(pte_val(*pte) | (_PAGE_VALID | _PAGE_PRESENT)));
+
+	preempt_disable();
+	local_flush_tlb_one(addr);
+	preempt_enable();
+	return true;
+}
+
+#endif /* _ASM_LOONGARCH_KFENCE_H */
diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
index 716a7fcab15e..ff0c4ff34c0a 100644
--- a/arch/loongarch/include/asm/pgtable.h
+++ b/arch/loongarch/include/asm/pgtable.h
@@ -77,6 +77,12 @@ extern unsigned long zero_page_mask;
 	(virt_to_page((void *)(empty_zero_page + (((unsigned long)(vaddr)) & zero_page_mask))))
 #define __HAVE_COLOR_ZERO_PAGE
 
+#ifdef CONFIG_KFENCE
+#define KFENCE_AREA_SIZE	(((CONFIG_KFENCE_NUM_OBJECTS + 1) * 2 + 2) * PAGE_SIZE)
+#else
+#define KFENCE_AREA_SIZE	0
+#endif
+
 /*
  * TLB refill handlers may also map the vmalloc area into xkvrange.
  * Avoid the first couple of pages so NULL pointer dereferences will
@@ -88,11 +94,16 @@ extern unsigned long zero_page_mask;
 #define VMALLOC_START	MODULES_END
 #define VMALLOC_END	\
 	(vm_map_base +	\
-	 min(PTRS_PER_PGD * PTRS_PER_PUD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE, (1UL << cpu_vabits)) - PMD_SIZE - VMEMMAP_SIZE)
+	 min(PTRS_PER_PGD * PTRS_PER_PUD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE, (1UL << cpu_vabits)) - PMD_SIZE - VMEMMAP_SIZE - KFENCE_AREA_SIZE)
 
 #define vmemmap		((struct page *)((VMALLOC_END + PMD_SIZE) & PMD_MASK))
 #define VMEMMAP_END	((unsigned long)vmemmap + VMEMMAP_SIZE - 1)
 
+#ifdef CONFIG_KFENCE
+#define KFENCE_AREA_START	VMEMMAP_END
+#define KFENCE_AREA_END		(KFENCE_AREA_START + KFENCE_AREA_SIZE)
+#endif
+
 #define pte_ERROR(e) \
 	pr_err("%s:%d: bad pte %016lx.\n", __FILE__, __LINE__, pte_val(e))
 #ifndef __PAGETABLE_PMD_FOLDED
diff --git a/arch/loongarch/mm/fault.c b/arch/loongarch/mm/fault.c
index da5b6d518cdb..c0319128b221 100644
--- a/arch/loongarch/mm/fault.c
+++ b/arch/loongarch/mm/fault.c
@@ -23,6 +23,7 @@
 #include <linux/kprobes.h>
 #include <linux/perf_event.h>
 #include <linux/uaccess.h>
+#include <linux/kfence.h>
 
 #include <asm/branch.h>
 #include <asm/mmu_context.h>
@@ -30,7 +31,8 @@
 
 int show_unhandled_signals = 1;
 
-static void __kprobes no_context(struct pt_regs *regs, unsigned long address)
+static void __kprobes no_context(struct pt_regs *regs, unsigned long address,
+				 unsigned long write)
 {
 	const int field = sizeof(unsigned long) * 2;
 
@@ -38,6 +40,9 @@ static void __kprobes no_context(struct pt_regs *regs, unsigned long address)
 	if (fixup_exception(regs))
 		return;
 
+	if (kfence_handle_page_fault(address, write, regs))
+		return;
+
 	/*
 	 * Oops. The kernel tried to access some bad page. We'll have to
 	 * terminate things with extreme prejudice.
@@ -51,14 +56,15 @@ static void __kprobes no_context(struct pt_regs *regs, unsigned long address)
 	die("Oops", regs);
 }
 
-static void __kprobes do_out_of_memory(struct pt_regs *regs, unsigned long address)
+static void __kprobes do_out_of_memory(struct pt_regs *regs, unsigned long address,
+				       unsigned long write)
 {
 	/*
 	 * We ran out of memory, call the OOM killer, and return the userspace
 	 * (which will retry the fault, or kill us if we got oom-killed).
 	 */
 	if (!user_mode(regs)) {
-		no_context(regs, address);
+		no_context(regs, address, write);
 		return;
 	}
 	pagefault_out_of_memory();
@@ -69,7 +75,7 @@ static void __kprobes do_sigbus(struct pt_regs *regs,
 {
 	/* Kernel mode? Handle exceptions or die */
 	if (!user_mode(regs)) {
-		no_context(regs, address);
+		no_context(regs, address, write);
 		return;
 	}
 
@@ -90,7 +96,7 @@ static void __kprobes do_sigsegv(struct pt_regs *regs,
 
 	/* Kernel mode? Handle exceptions or die */
 	if (!user_mode(regs)) {
-		no_context(regs, address);
+		no_context(regs, address, write);
 		return;
 	}
 
@@ -149,7 +155,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs,
 	 */
 	if (address & __UA_LIMIT) {
 		if (!user_mode(regs))
-			no_context(regs, address);
+			no_context(regs, address, write);
 		else
 			do_sigsegv(regs, write, address, si_code);
 		return;
@@ -211,7 +217,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs,
 
 	if (fault_signal_pending(fault, regs)) {
 		if (!user_mode(regs))
-			no_context(regs, address);
+			no_context(regs, address, write);
 		return;
 	}
 
@@ -232,7 +238,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs,
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		mmap_read_unlock(mm);
 		if (fault & VM_FAULT_OOM) {
-			do_out_of_memory(regs, address);
+			do_out_of_memory(regs, address, write);
 			return;
 		} else if (fault & VM_FAULT_SIGSEGV) {
 			do_sigsegv(regs, write, address, si_code);
-- 
2.34.1

Re: [PATCH 0/4 v3] Add KFENCE support for LoongArch

[Huacai Chen]

Hi, Enze,

I applied this series (with some small modifications) together with KASAN at:
https://github.com/chenhuacai/linux/commits/loongarch-next

Please confirm everything works well for you.

Huacai

On Tue, Aug 1, 2023 at 10:59 AM Enze Li <lienze@kylinos.cn> wrote:
>
> Hi all,
>
> This patchset adds KFENCE support on LoongArch.
>
> To run the testcases, you will need to enable the following options,
>
> -> Kernel hacking
>    [*] Tracers
>        [*] Support for tracing block IO actions (NEW)
>    -> Kernel Testing and Coverage
>       <*> KUnit - Enable support for unit tests
>
> and then,
>
> -> Kernel hacking
>    -> Memory Debugging
>       [*] KFENCE: low-overhead sampling-based memory safety error detector (NEW)
>           <*> KFENCE integration test suite (NEW)
>
> With these options enabled, KFENCE will be tested during kernel startup.
> And normally, you might get the following feedback,
>
> ========================================================
> [   35.326363 ] # kfence: pass:23 fail:0 skip:2 total:25
> [   35.326486 ] # Totals: pass:23 fail:0 skip:2 total:25
> [   35.326621 ] ok 1 kfence
> ========================================================
>
> you might notice that 2 testcases have been skipped.  If you tend to run
> all testcases, please enable CONFIG_INIT_ON_FREE_DEFAULT_ON, you can
> find it here,
>
> -> Security options
>    -> Kernel hardening options
>       -> Memory initialization
>          [*] Enable heap memory zeroing on free by default
>
> and you might get all testcases passed.
> ========================================================
> [   35.531860 ] # kfence: pass:25 fail:0 skip:0 total:25
> [   35.531999 ] # Totals: pass:25 fail:0 skip:0 total:25
> [   35.532135 ] ok 1 kfence
> ========================================================
>
> v3:
>    * Address Huacai's comments.
>    * Fix a bug that Jackie Liu pointed out.
>    * Rewrite arch_stack_walk() with the suggestion of Jinyang He.
>
> v2:
>    * Address Huacai's comments.
>    * Fix typos in commit message.
>
> Thanks,
> Enze
>
> Enze Li (4):
>   KFENCE: Defer the assignment of the local variable addr
>   LoongArch: mm: Add page table mapped mode support
>   LoongArch: Get stack without NMI when providing regs parameter
>   LoongArch: Add KFENCE support
>
>  arch/loongarch/Kconfig               |  1 +
>  arch/loongarch/include/asm/kfence.h  | 66 ++++++++++++++++++++++++++++
>  arch/loongarch/include/asm/page.h    |  8 +++-
>  arch/loongarch/include/asm/pgtable.h | 16 ++++++-
>  arch/loongarch/kernel/stacktrace.c   | 18 ++++----
>  arch/loongarch/mm/fault.c            | 22 ++++++----
>  arch/loongarch/mm/pgtable.c          |  7 +++
>  mm/kfence/core.c                     |  5 ++-
>  8 files changed, 123 insertions(+), 20 deletions(-)
>  create mode 100644 arch/loongarch/include/asm/kfence.h
>
> --
> 2.34.1
>

Re: [PATCH 0/4 v3] Add KFENCE support for LoongArch

[Enze Li]

On Wed, Aug 02 2023 at 11:12:23 PM +0800, Huacai Chen wrote:

> Hi, Enze,
>
> I applied this series (with some small modifications) together with KASAN at:
> https://github.com/chenhuacai/linux/commits/loongarch-next
>
> Please confirm everything works well for you.

Hi Huacai,

Thanks for your patience these days.

I've tested this on both a physical machine and a qemu VM.  It works
well.

BTW, if there're any modifications, bugs or improvments to KFENCE on
LoongArch in the future, feel free to Cc me.  I'll appreciate it. :)

Best Regards,
Enze

>
> Huacai
>
> On Tue, Aug 1, 2023 at 10:59 AM Enze Li <lienze@kylinos.cn> wrote:
>>
>> Hi all,
>>
>> This patchset adds KFENCE support on LoongArch.
>>
>> To run the testcases, you will need to enable the following options,
>>
>> -> Kernel hacking
>>    [*] Tracers
>>        [*] Support for tracing block IO actions (NEW)
>>    -> Kernel Testing and Coverage
>>       <*> KUnit - Enable support for unit tests
>>
>> and then,
>>
>> -> Kernel hacking
>>    -> Memory Debugging
>>       [*] KFENCE: low-overhead sampling-based memory safety error detector (NEW)
>>           <*> KFENCE integration test suite (NEW)
>>
>> With these options enabled, KFENCE will be tested during kernel startup.
>> And normally, you might get the following feedback,
>>
>> ========================================================
>> [   35.326363 ] # kfence: pass:23 fail:0 skip:2 total:25
>> [   35.326486 ] # Totals: pass:23 fail:0 skip:2 total:25
>> [   35.326621 ] ok 1 kfence
>> ========================================================
>>
>> you might notice that 2 testcases have been skipped.  If you tend to run
>> all testcases, please enable CONFIG_INIT_ON_FREE_DEFAULT_ON, you can
>> find it here,
>>
>> -> Security options
>>    -> Kernel hardening options
>>       -> Memory initialization
>>          [*] Enable heap memory zeroing on free by default
>>
>> and you might get all testcases passed.
>> ========================================================
>> [   35.531860 ] # kfence: pass:25 fail:0 skip:0 total:25
>> [   35.531999 ] # Totals: pass:25 fail:0 skip:0 total:25
>> [   35.532135 ] ok 1 kfence
>> ========================================================
>>
>> v3:
>>    * Address Huacai's comments.
>>    * Fix a bug that Jackie Liu pointed out.
>>    * Rewrite arch_stack_walk() with the suggestion of Jinyang He.
>>
>> v2:
>>    * Address Huacai's comments.
>>    * Fix typos in commit message.
>>
>> Thanks,
>> Enze
>>
>> Enze Li (4):
>>   KFENCE: Defer the assignment of the local variable addr
>>   LoongArch: mm: Add page table mapped mode support
>>   LoongArch: Get stack without NMI when providing regs parameter
>>   LoongArch: Add KFENCE support
>>
>>  arch/loongarch/Kconfig               |  1 +
>>  arch/loongarch/include/asm/kfence.h  | 66 ++++++++++++++++++++++++++++
>>  arch/loongarch/include/asm/page.h    |  8 +++-
>>  arch/loongarch/include/asm/pgtable.h | 16 ++++++-
>>  arch/loongarch/kernel/stacktrace.c   | 18 ++++----
>>  arch/loongarch/mm/fault.c            | 22 ++++++----
>>  arch/loongarch/mm/pgtable.c          |  7 +++
>>  mm/kfence/core.c                     |  5 ++-
>>  8 files changed, 123 insertions(+), 20 deletions(-)
>>  create mode 100644 arch/loongarch/include/asm/kfence.h
>>
>> --
>> 2.34.1
>>