On Wed, Apr 22, 2020 at 12:35:58AM +0700, Phong Tran wrote: > follow the suggestion from > https://github.com/KSPP/linux/issues/35 > > Signed-off-by: Phong Tran <tranmanphong@xxxxxxxxx> > --- > Change since v1: > - Update the Kconfig help text > - Don't check the return value of debugfs_create_file() > - Tested on QEMU aarch64 As on v1, I think that this should be generic across all architectures with CONFIG_DEBUG_WX. Adding this only on arm64 under CONFIG_PTDUMP_DEBUGFS (which does not generally imply a WX check) doesn't seem right. Maybe we need a new ARCH_HAS_CHECK_WX config to make that simpler, but that seems simple to me. Thanks, Marm. > root@qemuarm64:~# zcat /proc/config.gz | grep PTDUMP > CONFIG_GENERIC_PTDUMP=y > CONFIG_PTDUMP_CORE=y > CONFIG_PTDUMP_DEBUGFS=y > root@qemuarm64:~# uname -a > Linux qemuarm64 5.7.0-rc2-00001-g20ddb383c313 #3 SMP PREEMPT Tue Apr 21 23:18:56 +07 2020 aarch64 GNU/Linux > root@qemuarm64:~# echo 1 > /sys/kernel/debug/check_wx_pages > [ 63.261868] Checked W+X mappings: passed, no W+X pages found > --- > arch/arm64/Kconfig.debug | 5 ++++- > arch/arm64/include/asm/ptdump.h | 2 ++ > arch/arm64/mm/dump.c | 1 + > arch/arm64/mm/ptdump_debugfs.c | 18 ++++++++++++++++++ > 4 files changed, 25 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug > index a1efa246c9ed..cd82c9d3664a 100644 > --- a/arch/arm64/Kconfig.debug > +++ b/arch/arm64/Kconfig.debug > @@ -48,7 +48,10 @@ config DEBUG_WX > of other unfixed kernel bugs easier. > > There is no runtime or memory usage effect of this option > - once the kernel has booted up - it's a one time check. > + once the kernel has booted up - it's a one time check at > + boot, and can also be triggered at runtime by echo "1" to > + "check_wx_pages". The "check_wx_pages" is available only with > + CONFIG_PTDUMP_DEBUGFS is enabled. > > If in doubt, say "Y". > > diff --git a/arch/arm64/include/asm/ptdump.h b/arch/arm64/include/asm/ptdump.h > index 38187f74e089..c90a6ec6f59b 100644 > --- a/arch/arm64/include/asm/ptdump.h > +++ b/arch/arm64/include/asm/ptdump.h > @@ -24,9 +24,11 @@ struct ptdump_info { > void ptdump_walk(struct seq_file *s, struct ptdump_info *info); > #ifdef CONFIG_PTDUMP_DEBUGFS > void ptdump_debugfs_register(struct ptdump_info *info, const char *name); > +void ptdump_check_wx_init(void); > #else > static inline void ptdump_debugfs_register(struct ptdump_info *info, > const char *name) { } > +static inline void ptdump_check_wx_init(void) { } > #endif > void ptdump_check_wx(void); > #endif /* CONFIG_PTDUMP_CORE */ > diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c > index 860c00ec8bd3..60c99a047763 100644 > --- a/arch/arm64/mm/dump.c > +++ b/arch/arm64/mm/dump.c > @@ -378,6 +378,7 @@ static int ptdump_init(void) > #endif > ptdump_initialize(); > ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables"); > + ptdump_check_wx_init(); > return 0; > } > device_initcall(ptdump_init); > diff --git a/arch/arm64/mm/ptdump_debugfs.c b/arch/arm64/mm/ptdump_debugfs.c > index d29d722ec3ec..6b0aa16cb17b 100644 > --- a/arch/arm64/mm/ptdump_debugfs.c > +++ b/arch/arm64/mm/ptdump_debugfs.c > @@ -20,3 +20,21 @@ void ptdump_debugfs_register(struct ptdump_info *info, const char *name) > { > debugfs_create_file(name, 0400, NULL, info, &ptdump_fops); > } > + > +static int check_wx_debugfs_set(void *data, u64 val) > +{ > + if (val != 1ULL) > + return -EINVAL; > + > + ptdump_check_wx(); > + > + return 0; > +} > + > +DEFINE_SIMPLE_ATTRIBUTE(check_wx_fops, NULL, check_wx_debugfs_set, "%llu\n"); > + > +void ptdump_check_wx_init(void) > +{ > + debugfs_create_file("check_wx_pages", 0200, NULL, > + NULL, &check_wx_fops) ? 0 : -ENOMEM; > +} > -- > 2.20.1 >
