The patch titled
Kprobes: i386 fix for mark ro data
has been added to the -mm tree. Its filename is
kprobes-i386-fix-for-mark-ro-data.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Kprobes: i386 fix for mark ro data
From: "S. P. Prasanna" <prasanna@xxxxxxxxxx>
Fix the problem of page protection introduced by CONFIG_DEBUG_RODATA.
CONFIG_DEBUG_RODATA marks the text pages as read-only, hence kprobes is
unable to insert breakpoints in the kernel text. This patch overrides the
page protection when adding or removing a probe for the i386 architecture.
Signed-off-by: Prasanna S P<prasanna@xxxxxxxxxx>
Acked-by: Jim Keniston <jkenisto@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/i386/kernel/kprobes.c | 26 ++++++++++++++++++++++++++
arch/i386/mm/init.c | 2 ++
include/asm-i386/kprobes.h | 12 ++++++++++++
include/asm-i386/pgtable.h | 2 ++
4 files changed, 42 insertions(+)
diff -puN arch/i386/kernel/kprobes.c~kprobes-i386-fix-for-mark-ro-data arch/i386/kernel/kprobes.c
--- a/arch/i386/kernel/kprobes.c~kprobes-i386-fix-for-mark-ro-data
+++ a/arch/i386/kernel/kprobes.c
@@ -169,16 +169,42 @@ int __kprobes arch_prepare_kprobe(struct
void __kprobes arch_arm_kprobe(struct kprobe *p)
{
+ unsigned long addr = (unsigned long) p->addr;
+ int page_readonly = 0;
+
+ if (kernel_readonly_text(addr)) {
+ page_readonly = 1;
+ change_page_attr(virt_to_page(addr), 1, PAGE_KERNEL_RWX);
+ global_flush_tlb();
+ }
+
*p->addr = BREAKPOINT_INSTRUCTION;
flush_icache_range((unsigned long) p->addr,
(unsigned long) p->addr + sizeof(kprobe_opcode_t));
+
+ if (page_readonly) {
+ change_page_attr(virt_to_page(addr), 1, PAGE_KERNEL_RX);
+ global_flush_tlb();
+ }
}
void __kprobes arch_disarm_kprobe(struct kprobe *p)
{
+ unsigned long addr = (unsigned long) p->addr;
+ int page_readonly = 0;
+
+ if (kernel_readonly_text(addr)) {
+ page_readonly = 1;
+ change_page_attr(virt_to_page(addr), 1, PAGE_KERNEL_RWX);
+ global_flush_tlb();
+ }
*p->addr = p->opcode;
flush_icache_range((unsigned long) p->addr,
(unsigned long) p->addr + sizeof(kprobe_opcode_t));
+ if (page_readonly) {
+ change_page_attr(virt_to_page(addr), 1, PAGE_KERNEL_RX);
+ global_flush_tlb();
+ }
}
void __kprobes arch_remove_kprobe(struct kprobe *p)
diff -puN arch/i386/mm/init.c~kprobes-i386-fix-for-mark-ro-data arch/i386/mm/init.c
--- a/arch/i386/mm/init.c~kprobes-i386-fix-for-mark-ro-data
+++ a/arch/i386/mm/init.c
@@ -45,6 +45,7 @@
#include <asm/sections.h>
#include <asm/paravirt.h>
+int kernel_text_is_ro;
unsigned int __VMALLOC_RESERVE = 128 << 20;
DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
@@ -808,6 +809,7 @@ void mark_rodata_ro(void)
change_page_attr(virt_to_page(start),
size >> PAGE_SHIFT, PAGE_KERNEL_RX);
printk("Write protecting the kernel text: %luk\n", size >> 10);
+ kernel_text_is_ro = 1;
}
start += size;
diff -puN include/asm-i386/kprobes.h~kprobes-i386-fix-for-mark-ro-data include/asm-i386/kprobes.h
--- a/include/asm-i386/kprobes.h~kprobes-i386-fix-for-mark-ro-data
+++ a/include/asm-i386/kprobes.h
@@ -26,6 +26,8 @@
*/
#include <linux/types.h>
#include <linux/ptrace.h>
+#include <linux/pfn.h>
+#include <asm-generic/sections.h>
#define __ARCH_WANT_KPROBES_INSN_SLOT
@@ -90,4 +92,14 @@ static inline void restore_interrupts(st
extern int kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data);
+extern int kernel_text_is_ro;
+static inline int kernel_readonly_text(unsigned long address)
+{
+
+ if (kernel_text_is_ro && ((address >= PFN_ALIGN(_text))
+ && (address < PFN_ALIGN(_etext))))
+ return 1;
+
+ return 0;
+}
#endif /* _ASM_KPROBES_H */
diff -puN include/asm-i386/pgtable.h~kprobes-i386-fix-for-mark-ro-data include/asm-i386/pgtable.h
--- a/include/asm-i386/pgtable.h~kprobes-i386-fix-for-mark-ro-data
+++ a/include/asm-i386/pgtable.h
@@ -159,6 +159,7 @@ void paging_init(void);
extern unsigned long long __PAGE_KERNEL, __PAGE_KERNEL_EXEC;
#define __PAGE_KERNEL_RO (__PAGE_KERNEL & ~_PAGE_RW)
#define __PAGE_KERNEL_RX (__PAGE_KERNEL_EXEC & ~_PAGE_RW)
+#define __PAGE_KERNEL_RWX (__PAGE_KERNEL_EXEC | _PAGE_RW)
#define __PAGE_KERNEL_NOCACHE (__PAGE_KERNEL | _PAGE_PCD)
#define __PAGE_KERNEL_LARGE (__PAGE_KERNEL | _PAGE_PSE)
#define __PAGE_KERNEL_LARGE_EXEC (__PAGE_KERNEL_EXEC | _PAGE_PSE)
@@ -167,6 +168,7 @@ extern unsigned long long __PAGE_KERNEL,
#define PAGE_KERNEL_RO __pgprot(__PAGE_KERNEL_RO)
#define PAGE_KERNEL_EXEC __pgprot(__PAGE_KERNEL_EXEC)
#define PAGE_KERNEL_RX __pgprot(__PAGE_KERNEL_RX)
+#define PAGE_KERNEL_RWX __pgprot(__PAGE_KERNEL_RWX)
#define PAGE_KERNEL_NOCACHE __pgprot(__PAGE_KERNEL_NOCACHE)
#define PAGE_KERNEL_LARGE __pgprot(__PAGE_KERNEL_LARGE)
#define PAGE_KERNEL_LARGE_EXEC __pgprot(__PAGE_KERNEL_LARGE_EXEC)
_
Patches currently in -mm which might be from prasanna@xxxxxxxxxx are
kprobes-x86_64-fix-for-mark-ro-data.patch
kprobes-i386-fix-for-mark-ro-data.patch
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