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Date: Tue, 24 Jan 2017 18:41:59 +0000
From: Mark Rutland <mark.rutland@....com>
To: Jinbum Park <jinb.park7@...il.com>
Cc: tglx@...utronix.de, mingo@...hat.com, hpa@...or.com, x86@...nel.org,
keescook@...omium.org, arjan@...ux.intel.com,
akpm@...uxfoundation.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, labbott@...hat.com,
kernel-hardening@...ts.openwall.com,
kernel-janitors@...r.kernel.org, linux@...linux.org.uk
Subject: Re: [PATCH v3] mm: add arch-independent testcases for RODATA
On Wed, Jan 25, 2017 at 01:04:34AM +0900, Jinbum Park wrote:
> 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 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,
> Move x86's testcases to shared location able to be called by other archs.
> and move declaration of rodata_test_data to separate header file.
>
> Signed-off-by: Jinbum Park <jinb.park7@...il.com>
> ---
> v3: Use probe_kernel_write() instead of put_user()
> Move declaration of rodata_test_data to separate header (rodata_test.h)
> Fix a kbuild-test-robot-error related to DEBUG_NX_TEST
>
> v2: Restore original credit of mm/rodata_test.c
>
> arch/x86/Kconfig.debug | 10 +-----
> 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 | 4 +--
> include/linux/rodata_test.h | 24 +++++++++++++
> mm/Kconfig.debug | 7 ++++
> mm/Makefile | 1 +
> mm/rodata_test.c | 63 ++++++++++++++++++++++++++++++++
> 10 files changed, 98 insertions(+), 101 deletions(-)
> delete mode 100644 arch/x86/kernel/test_rodata.c
> create mode 100644 include/linux/rodata_test.h
> create mode 100644 mm/rodata_test.c
> diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
> index 928d657..874b57c 100644
> --- a/arch/x86/mm/init_32.c
> +++ b/arch/x86/mm/init_32.c
> @@ -51,6 +51,7 @@
> #include <asm/cacheflush.h>
> #include <asm/page_types.h>
> #include <asm/init.h>
> +#include <linux/rodata_test.h>
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 5fff913..663d475 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -54,6 +54,7 @@
> #include <asm/init.h>
> #include <asm/uv/uv.h>
> #include <asm/setup.h>
> +#include <linux/rodata_test.h>
Rather than fixing up the include here, could we move the rodata_test()
call out into mark_readonly()? e.g.
diff --git a/init/main.c b/init/main.c
index b0c9d6f..d72a8d0 100644
--- a/init/main.c
+++ b/init/main.c
@@ -82,6 +82,7 @@
#include <linux/proc_ns.h>
#include <linux/io.h>
#include <linux/cache.h>
+#include <linux/rodata_test.h>
#include <asm/io.h>
#include <asm/bugs.h>
@@ -937,10 +938,12 @@ static int __init set_debug_rodata(char *str)
#ifdef CONFIG_DEBUG_RODATA
static void mark_readonly(void)
{
- if (rodata_enabled)
+ if (rodata_enabled) {
mark_rodata_ro();
- else
+ rodata_test();
+ } else {
pr_info("Kernel memory protection disabled.\n");
+ }
}
#else
static inline void mark_readonly(void)
... that would remove a few lines of code, and we wouldn't have to add
more in other architectures.
I've given this a go with that applied on arm64. It reported success,
and with mark_rodata_ro() hacked out it detected that .rodata was
writeable.
Thanks,
Mark.
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