[PATCH 1/2] powerpc: kprobes: blacklist exception handlers

[Naveen N. Rao]

Introduce __head_end to mark end of the early fixed sections and use the
same to blacklist all exception handlers from kprobes.

Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/sections.h | 1 +
 arch/powerpc/kernel/kprobes.c       | 9 +++++++++
 arch/powerpc/kernel/vmlinux.lds.S   | 2 ++
 3 files changed, 12 insertions(+)

diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
index 7dc006b58369..5d0c5b103302 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h
@@ -10,6 +10,7 @@
 
 extern char __start_interrupts[];
 extern char __end_interrupts[];
+extern char __head_end[];
 
 extern char __prom_init_toc_start[];
 extern char __prom_init_toc_end[];
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 71286dfd76a0..59159337a097 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -35,6 +35,7 @@
 #include <asm/code-patching.h>
 #include <asm/cacheflush.h>
 #include <asm/sstep.h>
+#include <asm/sections.h>
 #include <linux/uaccess.h>
 
 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
@@ -112,6 +113,14 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
 	return addr;
 }
 
+bool arch_within_kprobe_blacklist(unsigned long addr)
+{
+	return  (addr >= (unsigned long)__kprobes_text_start &&
+		 addr < (unsigned long)__kprobes_text_end) ||
+		(addr >= (unsigned long)_stext &&
+		 addr < (unsigned long)__head_end);
+}
+
 int arch_prepare_kprobe(struct kprobe *p)
 {
 	int ret = 0;
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 7394b770ae1f..f6eee507e0b9 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -77,6 +77,8 @@ SECTIONS
 #endif
 	} :kernel
 
+	__head_end = .;
+
 	/*
 	 * If the build dies here, it's likely code in head_64.S is referencing
 	 * labels it can't reach, and the linker inserting stubs without the
-- 
2.12.1