| Message ID | 20170119145114.GA19772@pjb1027-Latitude-E5410 (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jan 19, 2017 at 11:51:14PM +0900, Jinbum Park wrote: > 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) This is clearly a rework and move of the existing x86 test, and not the addition of a completely new test (see Arjan's comment about his credit being removed...). I would recommend that you turn this into a series that makes the x86 code generic, then moves it out into a common location where it can be used by others. e.g. 1) make the test use put_user() 2) move the rodata_test() call and the prototype to a common location 3) move the test out to mm/ (with no changes to the file itself) Otherwise, comments below. > diff --git a/mm/rodata_test.c b/mm/rodata_test.c > new file mode 100644 > index 0000000..d5b0504 > --- /dev/null > +++ b/mm/rodata_test.c > @@ -0,0 +1,63 @@ > +/* > + * rodata_test.c: functional test for mark_rodata_ro function > + * > + * (C) Copyright 2017 Jinbum Park <jinb.park7@gmail.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/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; > + } As I mentioned in the original posting, you need to change to KERNEL_DS for the put_user. Russell's suggestion to use probe_kernel_write() is strictly better; please do that instead. Thanks, Mark.
1) make the test use put_user() 2) move the rodata_test() call and the prototype to a common location 3) move the test out to mm/ (with no changes to file itself) Where is the best place for common test file in general?? kernel/rodata_test.c include/rodata_test.h => Is it fine?? I can't see common file about rodata. So I'm confused where the best place is.
Where is the best place for common test file in general?? kernel/rodata_test.c include/rodata_test.h => Is it fine?? I can't see common file about rodata. So I'm confused where the best place is. 2017. 1. 20. 오전 12:58에 "Mark Rutland" <mark.rutland@arm.com>님이 작성: > On Thu, Jan 19, 2017 at 11:51:14PM +0900, Jinbum Park wrote: > > 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) > > This is clearly a rework and move of the existing x86 test, and not the > addition of a completely new test (see Arjan's comment about his credit > being removed...). > > I would recommend that you turn this into a series that makes the x86 > code generic, then moves it out into a common location where it can be > used by others. e.g. > > 1) make the test use put_user() > 2) move the rodata_test() call and the prototype to a common location > 3) move the test out to mm/ (with no changes to the file itself) > > Otherwise, comments below. > > > diff --git a/mm/rodata_test.c b/mm/rodata_test.c > > new file mode 100644 > > index 0000000..d5b0504 > > --- /dev/null > > +++ b/mm/rodata_test.c > > @@ -0,0 +1,63 @@ > > +/* > > + * rodata_test.c: functional test for mark_rodata_ro function > > + * > > + * (C) Copyright 2017 Jinbum Park <jinb.park7@gmail.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/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; > > + } > > As I mentioned in the original posting, you need to change to KERNEL_DS > for the put_user. > > Russell's suggestion to use probe_kernel_write() is strictly better; > please do that instead. > > Thanks, > Mark. >
On Fri, Jan 20, 2017 at 03:49:46PM +0900, park jinbum wrote: > Where is the best place for common test file in general?? > > kernel/rodata_test.c > include/rodata_test.h => Is it fine?? I had assumed you would use mm/rodata_test.c, as you do in this patch (i.e. a *new* common file). That seems fine to me. Thanks, Mark.
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@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 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..d5b0504 --- /dev/null +++ b/mm/rodata_test.c @@ -0,0 +1,63 @@ +/* + * rodata_test.c: functional test for mark_rodata_ro function + * + * (C) Copyright 2017 Jinbum Park <jinb.park7@gmail.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/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"); +}
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@gmail.com> --- 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 | 63 ++++++++++++++++++++++++++++++++ 10 files changed, 79 insertions(+), 104 deletions(-) delete mode 100644 arch/x86/kernel/test_rodata.c create mode 100644 mm/rodata_test.c