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 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
