[PATCH v7 13/14] kprobes: port blacklist kprobes to linker table

["Luis R. Rodriguez" <mcgrof@kernel.org>]

kprobe makes use of two sections, the one dealing with the actual
kprobes was recently ported using the standard section range API.
The blacklist functionality of kprobes is still using a custom
section and declaring its custom section using the linker script
as follows:

type  Linux-section custom section name  begin                    end
table .init.data    _kprobe_blacklist    __start_kprobe_blacklist __stop_kprobe_blacklist

This ports the _kprobe_blacklist custom section to the standard
Linux linker table API allowing us remove all the custom blacklist
kprobe section declarations from the linker script.

This has been tested by trying to register a kprobe on a blacklisted
symbol (these are declared with NOKPROBE_SYMBOL()), and confirms that
this fails to work as expected. This was tested with:

 # insmod samples/kprobes/kprobe_example.ko symbol="get_kprobe"

This fails to load as expected with:

insmod: ERROR: could not insert module samples/kprobes/kprobe_example.ko: Invalid parameters

v5: Use push_section_tbl() for _ASM_NOKPROBE() for x86, and
    _ASM_NOKPROBE_SYMBOL() on powerpc
v4: ported over _ASM_NOKPROBE_SYMBOL() on powerpc and
    ASM_NOKPROBE() on x86
v3: this patch was introduced in this series

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/powerpc/include/asm/ppc_asm.h |  4 ++--
 arch/x86/include/asm/asm.h         |  4 +++-
 include/asm-generic/kprobes.h      |  4 ++--
 include/asm-generic/vmlinux.lds.h  | 10 ----------
 include/linux/kprobes.h            |  2 ++
 kernel/kprobes.c                   | 11 ++++-------
 6 files changed, 13 insertions(+), 22 deletions(-)

diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index 0846413b3a2e..20cd9c00eef5 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -9,7 +9,7 @@
 #include <asm/processor.h>
 #include <asm/ppc-opcode.h>
 #include <asm/firmware.h>
-#include <asm/ranges.h>
+#include <asm/tables.h>
 
 #ifdef __ASSEMBLY__
 
@@ -266,7 +266,7 @@ GLUE(.,name):
  */
 #ifdef CONFIG_KPROBES
 #define _ASM_NOKPROBE_SYMBOL(entry)			\
-	.pushsection "_kprobe_blacklist","aw";		\
+	push_section_tbl(.init.data, _kprobe_blacklist, any, aw); \
 	PPC_LONG (entry) ;				\
 	.popsection
 #else
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 7acb51c49fec..48b1bc85c0e6 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -1,6 +1,8 @@
 #ifndef _ASM_X86_ASM_H
 #define _ASM_X86_ASM_H
 
+#include <asm/tables.h>
+
 #ifdef __ASSEMBLY__
 # define __ASM_FORM(x)	x
 # define __ASM_FORM_RAW(x)     x
@@ -74,7 +76,7 @@
 	_ASM_EXTABLE_HANDLE(from, to, ex_handler_ext)
 
 # define _ASM_NOKPROBE(entry)					\
-	.pushsection "_kprobe_blacklist","aw" ;			\
+	push_section_tbl_any(.init.data, _kprobe_blacklist, aw);\
 	_ASM_ALIGN ;						\
 	_ASM_PTR (entry);					\
 	.popsection
diff --git a/include/asm-generic/kprobes.h b/include/asm-generic/kprobes.h
index 02a26b975187..7d29a208390e 100644
--- a/include/asm-generic/kprobes.h
+++ b/include/asm-generic/kprobes.h
@@ -3,14 +3,14 @@
 
 #if defined(__KERNEL__) && !defined(__ASSEMBLY__)
 #ifdef CONFIG_KPROBES
+#include <linux/tables.h>
 #include <asm/ranges.h>
 /*
  * Blacklist ganerating macro. Specify functions which is not probed
  * by using this macro.
  */
 # define __NOKPROBE_SYMBOL(fname)				\
-static unsigned long __used					\
-	__attribute__((__section__("_kprobe_blacklist")))	\
+static LINKTABLE_INIT_DATA(_kprobe_blacklist, all)		\
 	_kbl_addr_##fname = (unsigned long)fname;
 # define NOKPROBE_SYMBOL(fname)	__NOKPROBE_SYMBOL(fname)
 /* Use this to forbid a kprobes attach on very low level functions */
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 499caf5b4361..9f062af1f728 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -114,15 +114,6 @@
 #define BRANCH_PROFILE()
 #endif
 
-#ifdef CONFIG_KPROBES
-#define KPROBE_BLACKLIST()	. = ALIGN(8);				      \
-				VMLINUX_SYMBOL(__start_kprobe_blacklist) = .; \
-				KEEP(*(_kprobe_blacklist))		      \
-				VMLINUX_SYMBOL(__stop_kprobe_blacklist) = .;
-#else
-#define KPROBE_BLACKLIST()
-#endif
-
 #ifdef CONFIG_EVENT_TRACING
 #define FTRACE_EVENTS()	. = ALIGN(8);					\
 			VMLINUX_SYMBOL(__start_ftrace_events) = .;	\
@@ -551,7 +542,6 @@
 	*(.init.rodata)							\
 	FTRACE_EVENTS()							\
 	TRACE_SYSCALLS()						\
-	KPROBE_BLACKLIST()						\
 	MEM_DISCARD(init.rodata)					\
 	CLK_OF_TABLES()							\
 	RESERVEDMEM_OF_TABLES()						\
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 445cc6fe7afa..2707820cbb56 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -44,8 +44,10 @@
 
 #ifdef CONFIG_KPROBES
 #include <linux/ranges.h>
+#include <linux/tables.h>
 
 DECLARE_SECTION_RANGE(kprobes);
+DECLARE_LINKTABLE(unsigned long, _kprobe_blacklist);
 
 /* kprobe_status settings */
 #define KPROBE_HIT_ACTIVE	0x00000001
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 82191f328e21..9d102ac95256 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2053,14 +2053,13 @@ NOKPROBE_SYMBOL(dump_kprobe);
  * since a kprobe need not necessarily be at the beginning
  * of a function.
  */
-static int __init populate_kprobe_blacklist(unsigned long *start,
-					     unsigned long *end)
+static int __init populate_kprobe_blacklist(void)
 {
 	unsigned long *iter;
 	struct kprobe_blacklist_entry *ent;
 	unsigned long entry, offset = 0, size = 0;
 
-	for (iter = start; iter < end; iter++) {
+	linktable_for_each(iter, _kprobe_blacklist) {
 		entry = arch_deref_entry_point((void *)*iter);
 
 		if (!kernel_text_address(entry) ||
@@ -2125,8 +2124,7 @@ static struct notifier_block kprobe_module_nb = {
 };
 
 /* Markers of _kprobe_blacklist section */
-extern unsigned long __start_kprobe_blacklist[];
-extern unsigned long __stop_kprobe_blacklist[];
+DEFINE_LINKTABLE_INIT_DATA(unsigned long, _kprobe_blacklist);
 
 /* Actual kprobes section range */
 DEFINE_SECTION_RANGE(kprobes, .text);
@@ -2143,8 +2141,7 @@ static int __init init_kprobes(void)
 		raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
 	}
 
-	err = populate_kprobe_blacklist(__start_kprobe_blacklist,
-					__stop_kprobe_blacklist);
+	err = populate_kprobe_blacklist();
 	if (err) {
 		pr_err("kprobes: failed to populate blacklist: %d\n", err);
 		pr_err("Please take care of using kprobes.\n");
-- 
2.11.0