[v2,1/9] riscv: add ARCH_HAS_SET_MEMORY support

Commit Message

Zong Li March 9, 2020, 8:22 a.m. UTC

Add set_memory_ro/rw/x/nx architecture hooks to change the page
attribution.

Use own set_memory.h rather than generic set_memory.h
(i.e. include/asm-generic/set_memory.h), because we want to add other
function prototypes here.

Signed-off-by: Zong Li <[e-mail]>
---
 arch/riscv/Kconfig                  |   1 +
 arch/riscv/include/asm/set_memory.h |  17 ++++
 arch/riscv/mm/Makefile              |   1 +
 arch/riscv/mm/pageattr.c            | 150 ++++++++++++++++++++++++++++
 4 files changed, 169 insertions(+)
 create mode 100644 arch/riscv/include/asm/set_memory.h
 create mode 100644 arch/riscv/mm/pageattr.c

Comments

kernel test robot March 9, 2020, 12:50 p.m. UTC | #1

Hi Zong,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on v5.6-rc5]
[also build test ERROR on next-20200306]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Zong-Li/Support-strict-kernel-memory-permissions-for-security/20200309-172554
base:    2c523b344dfa65a3738e7039832044aa133c75fb
config: riscv-nommu_virt_defconfig (attached as .config)
compiler: riscv64-linux-gcc (GCC) 7.5.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.5.0 make.cross ARCH=riscv 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <[e-mail]>

All errors (new ones prefixed by >>):

   arch/riscv/mm/pageattr.c: In function 'pageattr_pmd_entry':
>> arch/riscv/mm/pageattr.c:73:3: error: implicit declaration of function 'set_pmd'; did you mean 'set_pud'? [-Werror=implicit-function-declaration]
      set_pmd(pmd, val);
      ^~~~~~~
      set_pud
   arch/riscv/mm/pageattr.c: In function 'pageattr_pte_entry':
>> arch/riscv/mm/pageattr.c:85:2: error: implicit declaration of function 'set_pte'; did you mean 'set_pud'? [-Werror=implicit-function-declaration]
     set_pte(pte, val);
     ^~~~~~~
     set_pud
   cc1: some warnings being treated as errors

vim +73 arch/riscv/mm/pageattr.c

    65	
    66	static int pageattr_pmd_entry(pmd_t *pmd, unsigned long addr,
    67				      unsigned long next, struct mm_walk *walk)
    68	{
    69		pmd_t val = READ_ONCE(*pmd);
    70	
    71		if (pmd_leaf(val)) {
    72			val = __pmd(set_pageattr_masks(pmd_val(val), walk));
  > 73			set_pmd(pmd, val);
    74		}
    75	
    76		return 0;
    77	}
    78	
    79	static int pageattr_pte_entry(pte_t *pte, unsigned long addr,
    80				      unsigned long next, struct mm_walk *walk)
    81	{
    82		pte_t val = READ_ONCE(*pte);
    83	
    84		val = __pte(set_pageattr_masks(pte_val(val), walk));
  > 85		set_pte(pte, val);
    86	
    87		return 0;
    88	}
    89	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[e-mail]

Patch

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 6e81da55b5e4..76ed36543b3a 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -60,6 +60,7 @@  config RISCV
 	select HAVE_EBPF_JIT if 64BIT
 	select EDAC_SUPPORT
 	select ARCH_HAS_GIGANTIC_PAGE
+	select ARCH_HAS_SET_MEMORY
 	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
 	select SPARSEMEM_STATIC if 32BIT
 	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
new file mode 100644
index 000000000000..936f08063566
--- /dev/null
+++ b/arch/riscv/include/asm/set_memory.h
@@ -0,0 +1,17 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2019 SiFive
+ */
+
+#ifndef _ASM_RISCV_SET_MEMORY_H
+#define _ASM_RISCV_SET_MEMORY_H
+
+/*
+ * Functions to change memory attributes.
+ */
+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);
+
+#endif /* _ASM_RISCV_SET_MEMORY_H */
diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile
index 814e16a8d68a..b94643aee84c 100644
--- a/arch/riscv/mm/Makefile
+++ b/arch/riscv/mm/Makefile
@@ -10,6 +10,7 @@  obj-y += extable.o
 obj-$(CONFIG_MMU) += fault.o
 obj-y += cacheflush.o
 obj-y += context.o
+obj-y += pageattr.o
 
 ifeq ($(CONFIG_MMU),y)
 obj-$(CONFIG_SMP) += tlbflush.o
diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
new file mode 100644
index 000000000000..fcd59ef2835b
--- /dev/null
+++ b/arch/riscv/mm/pageattr.c
@@ -0,0 +1,150 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2019 SiFive
+ */
+
+#include <linux/pagewalk.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <asm/bitops.h>
+
+struct pageattr_masks {
+	pgprot_t set_mask;
+	pgprot_t clear_mask;
+};
+
+static unsigned long set_pageattr_masks(unsigned long val, struct mm_walk *walk)
+{
+	struct pageattr_masks *masks = walk->private;
+	unsigned long new_val = val;
+
+	new_val &= ~(pgprot_val(masks->clear_mask));
+	new_val |= (pgprot_val(masks->set_mask));
+
+	return new_val;
+}
+
+static int pageattr_pgd_entry(pgd_t *pgd, unsigned long addr,
+			      unsigned long next, struct mm_walk *walk)
+{
+	pgd_t val = READ_ONCE(*pgd);
+
+	if (pgd_leaf(val)) {
+		val = __pgd(set_pageattr_masks(pgd_val(val), walk));
+		set_pgd(pgd, val);
+	}
+
+	return 0;
+}
+
+static int pageattr_p4d_entry(p4d_t *p4d, unsigned long addr,
+			      unsigned long next, struct mm_walk *walk)
+{
+	p4d_t val = READ_ONCE(*p4d);
+
+	if (p4d_leaf(val)) {
+		val = __p4d(set_pageattr_masks(p4d_val(val), walk));
+		set_p4d(p4d, val);
+	}
+
+	return 0;
+}
+
+static int pageattr_pud_entry(pud_t *pud, unsigned long addr,
+			      unsigned long next, struct mm_walk *walk)
+{
+	pud_t val = READ_ONCE(*pud);
+
+	if (pud_leaf(val)) {
+		val = __pud(set_pageattr_masks(pud_val(val), walk));
+		set_pud(pud, val);
+	}
+
+	return 0;
+}
+
+static int pageattr_pmd_entry(pmd_t *pmd, unsigned long addr,
+			      unsigned long next, struct mm_walk *walk)
+{
+	pmd_t val = READ_ONCE(*pmd);
+
+	if (pmd_leaf(val)) {
+		val = __pmd(set_pageattr_masks(pmd_val(val), walk));
+		set_pmd(pmd, val);
+	}
+
+	return 0;
+}
+
+static int pageattr_pte_entry(pte_t *pte, unsigned long addr,
+			      unsigned long next, struct mm_walk *walk)
+{
+	pte_t val = READ_ONCE(*pte);
+
+	val = __pte(set_pageattr_masks(pte_val(val), walk));
+	set_pte(pte, val);
+
+	return 0;
+}
+
+static int pageattr_pte_hole(unsigned long addr, unsigned long next,
+			     int depth, struct mm_walk *walk)
+{
+	/* Nothing to do here */
+	return 0;
+}
+
+const static struct mm_walk_ops pageattr_ops = {
+	.pgd_entry = pageattr_pgd_entry,
+	.p4d_entry = pageattr_p4d_entry,
+	.pud_entry = pageattr_pud_entry,
+	.pmd_entry = pageattr_pmd_entry,
+	.pte_entry = pageattr_pte_entry,
+	.pte_hole = pageattr_pte_hole,
+};
+
+static int __set_memory(unsigned long addr, int numpages, pgprot_t set_mask,
+			pgprot_t clear_mask)
+{
+	int ret;
+	unsigned long start = addr;
+	unsigned long end = start + PAGE_SIZE * numpages;
+	struct pageattr_masks masks = {
+		.set_mask = set_mask,
+		.clear_mask = clear_mask
+	};
+
+	if (!numpages)
+		return 0;
+
+	down_read(&init_mm.mmap_sem);
+	ret =  walk_page_range_novma(&init_mm, start, end, &pageattr_ops, NULL,
+				     &masks);
+	up_read(&init_mm.mmap_sem);
+
+	flush_tlb_kernel_range(start, end);
+
+	return ret;
+}
+
+int set_memory_ro(unsigned long addr, int numpages)
+{
+	return __set_memory(addr, numpages, __pgprot(_PAGE_READ),
+			    __pgprot(_PAGE_WRITE));
+}
+
+int set_memory_rw(unsigned long addr, int numpages)
+{
+	return __set_memory(addr, numpages, __pgprot(_PAGE_READ | _PAGE_WRITE),
+			    __pgprot(0));
+}
+
+int set_memory_x(unsigned long addr, int numpages)
+{
+	return __set_memory(addr, numpages, __pgprot(_PAGE_EXEC), __pgprot(0));
+}
+
+int set_memory_nx(unsigned long addr, int numpages)
+{
+	return __set_memory(addr, numpages, __pgprot(0), __pgprot(_PAGE_EXEC));
+}