mm: add arch-independent testcases for RODATA

This patch makes 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 a 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 the above issues, write arch-independent testcases and move it
to shared location.

[jinb.park7@gmail.com: fix config dependency]
  Link: http://lkml.kernel.org/r/20170209131625.GA16954@pjb1027-Latitude-E5410
Link: http://lkml.kernel.org/r/20170129105436.GA9303@pjb1027-Latitude-E5410
Signed-off-by: Jinbum Park <jinb.park7@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Valentin Rothberg <valentinrothberg@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

6 files changed, 0 insertions, 103 deletions

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index c4cba00dbdee..63c1d13aaf9f 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 872877d930de..e7e1942edff7 100644
--- a/arch/x86/include/asm/cacheflush.h
+++ b/arch/x86/include/asm/cacheflush.h
@@ -90,18 +90,8 @@ void clflush_cache_range(void *addr, unsigned int size);
 
 #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 bdcdb3b3a219..84c00592d359 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_NMI_SELFTEST) += nmi_selftest.o
 
 obj-$(CONFIG_KVM_GUEST)		+= kvm.o kvmclock.o
diff --git a/arch/x86/kernel/test_rodata.c b/arch/x86/kernel/test_rodata.c
deleted file mode 100644
index 222e84e2432e..000000000000
--- 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@linux.intel.com>
- *
- * 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 928d657de829..2b4b53e6793f 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 97346f987ef2..15173d37f399 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);