Re: [patch][ia64]Refuse kprobe on ivt code

[Keshavamurthy Anil S <anil.s.keshavamurthy@intel.com>]

On Thu, Jun 23, 2005 at 06:38:33PM -0700, David Mosberger wrote:
> Please do the checking based on the .text.ivt section instead (and add
> the necessary labels to vmlinux.S and asm-ia64/sections.h).

Subject: Refuse kprobe insert on IVT code

Not safe to insert kprobes on IVT code.

This patch checks to see if the address on which Kprobes is being
inserted is  in ivt code and if it is in ivt code then
refuse to register kprobe.

Take 1: This patch is based on review comments from David Mosberger,
now checking based on .text.ivt

Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>

======================= arch/ia64/kernel/kprobes.c     |   14 ++++++++++++++
 arch/ia64/kernel/vmlinux.lds.S |    7 ++++++-
 include/asm-ia64/sections.h    |    1 +
 3 files changed, 21 insertions(+), 1 deletion(-)

Index: linux-2.6.12-mm1/arch/ia64/kernel/kprobes.c
=================================--- linux-2.6.12-mm1.orig/arch/ia64/kernel/kprobes.c
+++ linux-2.6.12-mm1/arch/ia64/kernel/kprobes.c
@@ -263,6 +263,14 @@ static inline void get_kprobe_inst(bundl
 	}
 }
 
+/* Returns non-zero if the addr is in the Interrupt Vector Table */
+static inline int in_ivt_functions(unsigned long addr)
+{
+	extern char __start_ivt_text[], __end_ivt_text[];
+	return (addr >= (unsigned long)__start_ivt_text
+		&& addr < (unsigned long)__end_ivt_text);
+}
+
 static int valid_kprobe_addr(int template, int slot, unsigned long addr)
 {
 	if ((slot > 2) || ((bundle_encoding[template][1] = L) && slot > 1)) {
@@ -271,6 +279,12 @@ static int valid_kprobe_addr(int templat
 		return -EINVAL;
 	}
 
+ 	if (in_ivt_functions(addr)) {
+ 		printk(KERN_WARNING "Kprobes can't be inserted inside "
+				"IVT code at 0x%lx\n", addr);
+ 		return -EINVAL;
+ 	}
+
 	if (slot = 1) {
 		printk(KERN_WARNING "Inserting kprobes on slot #1 "
 		       "is not supported\n");
Index: linux-2.6.12-mm1/arch/ia64/kernel/vmlinux.lds.S
=================================--- linux-2.6.12-mm1.orig/arch/ia64/kernel/vmlinux.lds.S
+++ linux-2.6.12-mm1/arch/ia64/kernel/vmlinux.lds.S
@@ -8,6 +8,11 @@
 #define LOAD_OFFSET	(KERNEL_START - KERNEL_TR_PAGE_SIZE)
 #include <asm-generic/vmlinux.lds.h>
 
+#define IVT_TEXT							\
+		VMLINUX_SYMBOL(__start_ivt_text) = .;			\
+		*(.text.ivt)						\
+		VMLINUX_SYMBOL(__end_ivt_text) = .;
+
 OUTPUT_FORMAT("elf64-ia64-little")
 OUTPUT_ARCH(ia64)
 ENTRY(phys_start)
@@ -39,7 +44,7 @@ SECTIONS
 
   .text : AT(ADDR(.text) - LOAD_OFFSET)
     {
-	*(.text.ivt)
+	IVT_TEXT
 	*(.text)
 	SCHED_TEXT
 	LOCK_TEXT
Index: linux-2.6.12-mm1/include/asm-ia64/sections.h
=================================--- linux-2.6.12-mm1.orig/include/asm-ia64/sections.h
+++ linux-2.6.12-mm1/include/asm-ia64/sections.h
@@ -17,6 +17,7 @@ extern char __start_gate_vtop_patchlist[
 extern char __start_gate_fsyscall_patchlist[], __end_gate_fsyscall_patchlist[];
 extern char __start_gate_brl_fsys_bubble_down_patchlist[], __end_gate_brl_fsys_bubble_down_patchlist[];
 extern char __start_unwind[], __end_unwind[];
+extern char __start_ivt_text[], __end_ivt_text[];
 
 #endif /* _ASM_IA64_SECTIONS_H */