s390: add ARCH_HAS_DEBUG_WX support
Checks the whole kernel address space for W+X mappings. Note that currently the first lowcore page unfortunately has to be mapped W+X. Therefore this not reported as an insecure mapping. For the very same reason the wording is also different to other architectures if the test passes: On s390 it is "no unexpected W+X pages found" instead of "no W+X pages found". Tested-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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6bf9a639e7
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08c8e685c7
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@ -60,6 +60,7 @@ config S390
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def_bool y
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def_bool y
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select ARCH_BINFMT_ELF_STATE
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select ARCH_BINFMT_ELF_STATE
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select ARCH_HAS_DEBUG_VM_PGTABLE
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select ARCH_HAS_DEBUG_VM_PGTABLE
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select ARCH_HAS_DEBUG_WX
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select ARCH_HAS_DEVMEM_IS_ALLOWED
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select ARCH_HAS_DEVMEM_IS_ALLOWED
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select ARCH_HAS_ELF_RANDOMIZE
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select ARCH_HAS_ELF_RANDOMIZE
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select ARCH_HAS_FORTIFY_SOURCE
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select ARCH_HAS_FORTIFY_SOURCE
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@ -774,6 +774,7 @@ CONFIG_MAGIC_SYSRQ=y
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CONFIG_DEBUG_PAGEALLOC=y
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CONFIG_DEBUG_PAGEALLOC=y
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CONFIG_PAGE_OWNER=y
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CONFIG_PAGE_OWNER=y
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CONFIG_DEBUG_RODATA_TEST=y
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CONFIG_DEBUG_RODATA_TEST=y
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CONFIG_DEBUG_WX=y
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CONFIG_PTDUMP_DEBUGFS=y
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CONFIG_PTDUMP_DEBUGFS=y
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CONFIG_DEBUG_OBJECTS=y
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CONFIG_DEBUG_OBJECTS=y
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CONFIG_DEBUG_OBJECTS_SELFTEST=y
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CONFIG_DEBUG_OBJECTS_SELFTEST=y
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@ -758,6 +758,7 @@ CONFIG_GDB_SCRIPTS=y
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CONFIG_FRAME_WARN=1024
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CONFIG_FRAME_WARN=1024
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CONFIG_DEBUG_SECTION_MISMATCH=y
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CONFIG_DEBUG_SECTION_MISMATCH=y
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CONFIG_MAGIC_SYSRQ=y
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CONFIG_MAGIC_SYSRQ=y
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CONFIG_DEBUG_WX=y
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CONFIG_PTDUMP_DEBUGFS=y
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CONFIG_PTDUMP_DEBUGFS=y
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CONFIG_DEBUG_MEMORY_INIT=y
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CONFIG_DEBUG_MEMORY_INIT=y
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CONFIG_PANIC_ON_OOPS=y
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CONFIG_PANIC_ON_OOPS=y
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14
arch/s390/include/asm/ptdump.h
Normal file
14
arch/s390/include/asm/ptdump.h
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@ -0,0 +1,14 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_S390_PTDUMP_H
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#define _ASM_S390_PTDUMP_H
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void ptdump_check_wx(void);
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static inline void debug_checkwx(void)
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{
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if (IS_ENABLED(CONFIG_DEBUG_WX))
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ptdump_check_wx();
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}
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#endif /* _ASM_S390_PTDUMP_H */
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@ -8,7 +8,7 @@ obj-y += page-states.o pageattr.o pgtable.o pgalloc.o
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obj-$(CONFIG_CMM) += cmm.o
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obj-$(CONFIG_CMM) += cmm.o
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obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
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obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
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obj-$(CONFIG_PTDUMP_DEBUGFS) += dump_pagetables.o
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obj-$(CONFIG_PTDUMP_CORE) += dump_pagetables.o
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obj-$(CONFIG_PGSTE) += gmap.o
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obj-$(CONFIG_PGSTE) += gmap.o
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KASAN_SANITIZE_kasan_init.o := n
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KASAN_SANITIZE_kasan_init.o := n
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@ -5,6 +5,7 @@
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#include <linux/debugfs.h>
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#include <linux/debugfs.h>
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#include <linux/mm.h>
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#include <linux/mm.h>
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#include <linux/kasan.h>
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#include <linux/kasan.h>
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#include <asm/ptdump.h>
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#include <asm/kasan.h>
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#include <asm/kasan.h>
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#include <asm/sections.h>
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#include <asm/sections.h>
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@ -47,6 +48,8 @@ struct pg_state {
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struct seq_file *seq;
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struct seq_file *seq;
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int level;
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int level;
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unsigned int current_prot;
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unsigned int current_prot;
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bool check_wx;
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unsigned long wx_pages;
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unsigned long start_address;
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unsigned long start_address;
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const struct addr_marker *marker;
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const struct addr_marker *marker;
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};
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};
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@ -81,6 +84,26 @@ static void print_prot(struct seq_file *m, unsigned int pr, int level)
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pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
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pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
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}
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}
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static void note_prot_wx(struct pg_state *st, unsigned long addr)
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{
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#ifdef CONFIG_DEBUG_WX
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if (!st->check_wx)
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return;
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if (st->current_prot & _PAGE_INVALID)
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return;
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if (st->current_prot & _PAGE_PROTECT)
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return;
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if (st->current_prot & _PAGE_NOEXEC)
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return;
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/* The first lowcore page is currently still W+X. */
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if (addr == PAGE_SIZE)
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return;
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WARN_ONCE(1, "s390/mm: Found insecure W+X mapping at address %pS\n",
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(void *)st->start_address);
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st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
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#endif /* CONFIG_DEBUG_WX */
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}
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static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
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static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
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{
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{
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int width = sizeof(unsigned long) * 2;
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int width = sizeof(unsigned long) * 2;
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@ -109,6 +132,7 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
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st->level = level;
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st->level = level;
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} else if (prot != st->current_prot || level != st->level ||
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} else if (prot != st->current_prot || level != st->level ||
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addr >= st->marker[1].start_address) {
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addr >= st->marker[1].start_address) {
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note_prot_wx(st, addr);
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pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
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pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
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width, st->start_address,
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width, st->start_address,
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width, addr);
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width, addr);
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@ -129,6 +153,40 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
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}
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}
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}
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}
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#ifdef CONFIG_DEBUG_WX
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void ptdump_check_wx(void)
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{
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struct pg_state st = {
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.ptdump = {
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.note_page = note_page,
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.range = (struct ptdump_range[]) {
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{.start = 0, .end = max_addr},
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{.start = 0, .end = 0},
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}
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},
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.seq = NULL,
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.level = -1,
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.current_prot = 0,
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.check_wx = true,
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.wx_pages = 0,
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.start_address = 0,
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.marker = (struct addr_marker[]) {
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{ .start_address = 0, .name = NULL},
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{ .start_address = -1, .name = NULL},
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},
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};
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if (!MACHINE_HAS_NX)
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return;
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ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
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if (st.wx_pages)
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pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages);
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else
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pr_info("Checked W+X mappings: passed, no unexpected W+X pages found\n");
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}
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#endif /* CONFIG_DEBUG_WX */
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#ifdef CONFIG_PTDUMP_DEBUGFS
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static int ptdump_show(struct seq_file *m, void *v)
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static int ptdump_show(struct seq_file *m, void *v)
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{
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{
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struct pg_state st = {
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struct pg_state st = {
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@ -142,6 +200,8 @@ static int ptdump_show(struct seq_file *m, void *v)
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.seq = m,
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.seq = m,
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.level = -1,
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.level = -1,
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.current_prot = 0,
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.current_prot = 0,
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.check_wx = false,
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.wx_pages = 0,
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.start_address = 0,
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.start_address = 0,
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.marker = address_markers,
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.marker = address_markers,
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};
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};
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@ -154,6 +214,7 @@ static int ptdump_show(struct seq_file *m, void *v)
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return 0;
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return 0;
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}
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}
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DEFINE_SHOW_ATTRIBUTE(ptdump);
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DEFINE_SHOW_ATTRIBUTE(ptdump);
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#endif /* CONFIG_PTDUMP_DEBUGFS */
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static int pt_dump_init(void)
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static int pt_dump_init(void)
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{
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{
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@ -167,7 +228,8 @@ static int pt_dump_init(void)
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address_markers[MODULES_NR].start_address = MODULES_VADDR;
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address_markers[MODULES_NR].start_address = MODULES_VADDR;
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address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
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address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
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address_markers[VMALLOC_NR].start_address = VMALLOC_START;
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address_markers[VMALLOC_NR].start_address = VMALLOC_START;
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debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
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if (IS_ENABLED(CONFIG_PTDUMP_DEBUGFS))
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debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
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return 0;
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return 0;
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}
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}
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device_initcall(pt_dump_init);
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device_initcall(pt_dump_init);
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@ -34,6 +34,7 @@
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#include <asm/processor.h>
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#include <asm/processor.h>
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#include <linux/uaccess.h>
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#include <linux/uaccess.h>
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#include <asm/pgalloc.h>
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#include <asm/pgalloc.h>
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#include <asm/ptdump.h>
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#include <asm/dma.h>
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#include <asm/dma.h>
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#include <asm/lowcore.h>
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#include <asm/lowcore.h>
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#include <asm/tlb.h>
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#include <asm/tlb.h>
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@ -129,6 +130,7 @@ void mark_rodata_ro(void)
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set_memory_ro((unsigned long)__start_ro_after_init, size >> PAGE_SHIFT);
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set_memory_ro((unsigned long)__start_ro_after_init, size >> PAGE_SHIFT);
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pr_info("Write protected read-only-after-init data: %luk\n", size >> 10);
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pr_info("Write protected read-only-after-init data: %luk\n", size >> 10);
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debug_checkwx();
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}
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}
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int set_memory_encrypted(unsigned long addr, int numpages)
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int set_memory_encrypted(unsigned long addr, int numpages)
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