[PATCH v2] mm: add arch-independent testcases for RODATA
From: Jinbum Park
Date: Thu Jan 19 2017 - 10:39:33 EST
This patch adds arch-independent testcases for RODATA.
Both x86 and x86_64 already have testcases for RODATA,
But they are arch-specific because using inline assembly directly.
and cacheflush.h is not suitable location for rodata-test related things.
Since they were in cacheflush.h,
If someone change the state of CONFIG_DEBUG_RODATA_TEST,
It cause overhead of kernel build.
To solve above issue,
write arch-independent testcases and move it to shared location. (main.c)
Signed-off-by: Jinbum Park <jinb.park7@xxxxxxxxx>
---
v2: Restore original credit of mm/rodata_test.c
arch/x86/Kconfig.debug | 8 -----
arch/x86/include/asm/cacheflush.h | 10 ------
arch/x86/kernel/Makefile | 1 -
arch/x86/kernel/test_rodata.c | 75 ---------------------------------------
arch/x86/mm/init_32.c | 4 ---
arch/x86/mm/init_64.c | 5 ---
init/main.c | 10 +++++-
mm/Kconfig.debug | 6 ++++
mm/Makefile | 1 +
mm/rodata_test.c | 64 +++++++++++++++++++++++++++++++++
10 files changed, 80 insertions(+), 104 deletions(-)
delete mode 100644 arch/x86/kernel/test_rodata.c
create mode 100644 mm/rodata_test.c
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 67eec55..5df54a8 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -74,14 +74,6 @@ config EFI_PGT_DUMP
issues with the mapping of the EFI runtime regions into that
table.
-config DEBUG_RODATA_TEST
- bool "Testcase for the marking rodata read-only"
- default y
- ---help---
- This option enables a testcase for the setting rodata read-only
- as well as for the change_page_attr() infrastructure.
- If in doubt, say "N"
-
config DEBUG_WX
bool "Warn on W+X mappings at boot"
select X86_PTDUMP_CORE
diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h
index 872877d..e7e1942e 100644
--- a/arch/x86/include/asm/cacheflush.h
+++ b/arch/x86/include/asm/cacheflush.h
@@ -90,18 +90,8 @@
#define mmio_flush_range(addr, size) clflush_cache_range(addr, size)
-extern const int rodata_test_data;
extern int kernel_set_to_readonly;
void set_kernel_text_rw(void);
void set_kernel_text_ro(void);
-#ifdef CONFIG_DEBUG_RODATA_TEST
-int rodata_test(void);
-#else
-static inline int rodata_test(void)
-{
- return 0;
-}
-#endif
-
#endif /* _ASM_X86_CACHEFLUSH_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 581386c..f6caf82 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -100,7 +100,6 @@ obj-$(CONFIG_HPET_TIMER) += hpet.o
obj-$(CONFIG_APB_TIMER) += apb_timer.o
obj-$(CONFIG_AMD_NB) += amd_nb.o
-obj-$(CONFIG_DEBUG_RODATA_TEST) += test_rodata.o
obj-$(CONFIG_DEBUG_NX_TEST) += test_nx.o
obj-$(CONFIG_DEBUG_NMI_SELFTEST) += nmi_selftest.o
diff --git a/arch/x86/kernel/test_rodata.c b/arch/x86/kernel/test_rodata.c
deleted file mode 100644
index 222e84e..0000000
--- a/arch/x86/kernel/test_rodata.c
+++ /dev/null
@@ -1,75 +0,0 @@
-/*
- * test_rodata.c: functional test for mark_rodata_ro function
- *
- * (C) Copyright 2008 Intel Corporation
- * Author: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; version 2
- * of the License.
- */
-#include <asm/cacheflush.h>
-#include <asm/sections.h>
-#include <asm/asm.h>
-
-int rodata_test(void)
-{
- unsigned long result;
- unsigned long start, end;
-
- /* test 1: read the value */
- /* If this test fails, some previous testrun has clobbered the state */
- if (!rodata_test_data) {
- printk(KERN_ERR "rodata_test: test 1 fails (start data)\n");
- return -ENODEV;
- }
-
- /* test 2: write to the variable; this should fault */
- /*
- * If this test fails, we managed to overwrite the data
- *
- * This is written in assembly to be able to catch the
- * exception that is supposed to happen in the correct
- * case
- */
-
- result = 1;
- asm volatile(
- "0: mov %[zero],(%[rodata_test])\n"
- " mov %[zero], %[rslt]\n"
- "1:\n"
- ".section .fixup,\"ax\"\n"
- "2: jmp 1b\n"
- ".previous\n"
- _ASM_EXTABLE(0b,2b)
- : [rslt] "=r" (result)
- : [rodata_test] "r" (&rodata_test_data), [zero] "r" (0UL)
- );
-
-
- if (!result) {
- printk(KERN_ERR "rodata_test: test data was not read only\n");
- return -ENODEV;
- }
-
- /* test 3: check the value hasn't changed */
- /* If this test fails, we managed to overwrite the data */
- if (!rodata_test_data) {
- printk(KERN_ERR "rodata_test: Test 3 fails (end data)\n");
- return -ENODEV;
- }
- /* test 4: check if the rodata section is 4Kb aligned */
- start = (unsigned long)__start_rodata;
- end = (unsigned long)__end_rodata;
- if (start & (PAGE_SIZE - 1)) {
- printk(KERN_ERR "rodata_test: .rodata is not 4k aligned\n");
- return -ENODEV;
- }
- if (end & (PAGE_SIZE - 1)) {
- printk(KERN_ERR "rodata_test: .rodata end is not 4k aligned\n");
- return -ENODEV;
- }
-
- return 0;
-}
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 928d657..2b4b53e 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -864,9 +864,6 @@ static noinline int do_test_wp_bit(void)
return flag;
}
-const int rodata_test_data = 0xC3;
-EXPORT_SYMBOL_GPL(rodata_test_data);
-
int kernel_set_to_readonly __read_mostly;
void set_kernel_text_rw(void)
@@ -939,7 +936,6 @@ void mark_rodata_ro(void)
set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
size >> 10);
- rodata_test();
#ifdef CONFIG_CPA_DEBUG
printk(KERN_INFO "Testing CPA: undo %lx-%lx\n", start, start + size);
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 97346f9..15173d3 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1000,9 +1000,6 @@ void __init mem_init(void)
mem_init_print_info(NULL);
}
-const int rodata_test_data = 0xC3;
-EXPORT_SYMBOL_GPL(rodata_test_data);
-
int kernel_set_to_readonly;
void set_kernel_text_rw(void)
@@ -1071,8 +1068,6 @@ void mark_rodata_ro(void)
all_end = roundup((unsigned long)_brk_end, PMD_SIZE);
set_memory_nx(text_end, (all_end - text_end) >> PAGE_SHIFT);
- rodata_test();
-
#ifdef CONFIG_CPA_DEBUG
printk(KERN_INFO "Testing CPA: undo %lx-%lx\n", start, end);
set_memory_rw(start, (end-start) >> PAGE_SHIFT);
diff --git a/init/main.c b/init/main.c
index e47373d..15b42bf 100644
--- a/init/main.c
+++ b/init/main.c
@@ -932,11 +932,19 @@ static int __init set_debug_rodata(char *str)
__setup("rodata=", set_debug_rodata);
#endif
+#ifdef CONFIG_DEBUG_RODATA_TEST
+void rodata_test(void);
+#else
+static inline void rodata_test(void) {}
+#endif
+
#ifdef CONFIG_DEBUG_RODATA
static void mark_readonly(void)
{
- if (rodata_enabled)
+ if (rodata_enabled) {
mark_rodata_ro();
+ rodata_test();
+ }
else
pr_info("Kernel memory protection disabled.\n");
}
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index afcc550..e4f22ce 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -90,3 +90,9 @@ config DEBUG_PAGE_REF
careful when enabling this feature because it adds about 30 KB to the
kernel code. However the runtime performance overhead is virtually
nil until the tracepoints are actually enabled.
+
+config DEBUG_RODATA_TEST
+ bool "Testcase for the marking rodata read-only"
+ depends on DEBUG_RODATA
+ ---help---
+ This option enables a testcase for the setting rodata read-only.
\ No newline at end of file
diff --git a/mm/Makefile b/mm/Makefile
index 433eaf9..d6199d4 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -83,6 +83,7 @@ obj-$(CONFIG_MEMORY_FAILURE) += memory-failure.o
obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o
obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o
obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o
+obj-$(CONFIG_DEBUG_RODATA_TEST) += rodata_test.o
obj-$(CONFIG_PAGE_OWNER) += page_owner.o
obj-$(CONFIG_CLEANCACHE) += cleancache.o
obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o
diff --git a/mm/rodata_test.c b/mm/rodata_test.c
new file mode 100644
index 0000000..fb953c0
--- /dev/null
+++ b/mm/rodata_test.c
@@ -0,0 +1,64 @@
+/*
+ * rodata_test.c: functional test for mark_rodata_ro function
+ *
+ * (C) Copyright 2008 Intel Corporation
+ * Author: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+#include <asm/uaccess.h>
+#include <asm/sections.h>
+
+const int rodata_test_data = 0xC3;
+EXPORT_SYMBOL_GPL(rodata_test_data);
+
+void rodata_test(void)
+{
+ unsigned long start, end, rodata_addr;
+ int zero = 0;
+
+ /* prepare test */
+ rodata_addr = ((unsigned long)&rodata_test_data);
+
+ /* test 1: read the value */
+ /* If this test fails, some previous testrun has clobbered the state */
+ if (!rodata_test_data) {
+ pr_err("rodata_test: test 1 fails (start data)\n");
+ return;
+ }
+
+ /* test 2: write to the variable; this should fault */
+ /*
+ * This must be written in assembly to be able to catch the
+ * exception that is supposed to happen in the correct case.
+ *
+ * So that put_user macro is used to write arch-independent assembly.
+ */
+ if (!put_user(zero, (int *)rodata_addr)) {
+ pr_err("rodata_test: test data was not read only\n");
+ return;
+ }
+
+ /* test 3: check the value hasn't changed */
+ if (rodata_test_data == zero) {
+ pr_err("rodata_test: test data was changed\n");
+ return;
+ }
+
+ /* test 4: check if the rodata section is PAGE_SIZE aligned */
+ start = (unsigned long)__start_rodata;
+ end = (unsigned long)__end_rodata;
+ if (start & (PAGE_SIZE - 1)) {
+ pr_err("rodata_test: start of .rodata is not page size aligned\n");
+ return;
+ }
+ if (end & (PAGE_SIZE - 1)) {
+ pr_err("rodata_test: end of .rodata is not page size aligned\n");
+ return;
+ }
+
+ pr_info("rodata_test: all tests were successful\n");
+}
--
1.9.1