Messages in this thread Patch in this message | | | From | Masami Hiramatsu <> | Subject | [PATCH -tip V3] [BUGFIX] kprobes/x86: Do not jump-optimize kprobes on irq entry code | Date | Tue, 25 Jul 2017 23:54:49 +0900 |
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Since the kernel segment registers are not prepared at the entry of irq-entry code, if a kprobe on such code is jump-optimized, accessing per-cpu variables may cause kernel panic. However, if the kprobe is not optimized, it kicks int3 exception and set segment registers correctly.
This checks probe-address and if it is in irq-entry code, it prohibits optimizing such kprobes. This means we can continuously probing such interrupt handlers by kprobes but it is not optimized anymore.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Reported-by: Francis Deslauriers <francis.deslauriers@efficios.com> Tested-by: Francis Deslauriers <francis.deslauriers@efficios.com> --- Changes in V3: - Define __irqentry_text_start/end symbols when CONFIG_OPTPROBES=y. --- arch/x86/kernel/kprobes/opt.c | 9 ++++++--- include/asm-generic/vmlinux.lds.h | 6 ++++-- include/linux/interrupt.h | 3 ++- 3 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index 69ea0bc..c26e7f9 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -29,6 +29,7 @@ #include <linux/kallsyms.h> #include <linux/ftrace.h> #include <linux/frame.h> +#include <linux/interrupt.h> #include <asm/text-patching.h> #include <asm/cacheflush.h> @@ -251,10 +252,12 @@ static int can_optimize(unsigned long paddr) /* * Do not optimize in the entry code due to the unstable - * stack handling. + * stack handling and registers setup. */ - if ((paddr >= (unsigned long)__entry_text_start) && - (paddr < (unsigned long)__entry_text_end)) + if (((paddr >= (unsigned long)__entry_text_start) && + (paddr < (unsigned long)__entry_text_end)) || + ((paddr >= (unsigned long)__irqentry_text_start) && + (paddr < (unsigned long)__irqentry_text_end))) return 0; /* Check there is enough space for a relative jump. */ diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index da0be9a..3092a1f 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -483,7 +483,8 @@ *(.entry.text) \ VMLINUX_SYMBOL(__entry_text_end) = .; -#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) +#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) || \ + defined(CONFIG_OPTPROBES) #define IRQENTRY_TEXT \ ALIGN_FUNCTION(); \ VMLINUX_SYMBOL(__irqentry_text_start) = .; \ @@ -493,7 +494,8 @@ #define IRQENTRY_TEXT #endif -#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) +#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) || \ + defined(CONFIG_OPTPROBES) #define SOFTIRQENTRY_TEXT \ ALIGN_FUNCTION(); \ VMLINUX_SYMBOL(__softirqentry_text_start) = .; \ diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index a2fdddd..a1b78f4 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -726,7 +726,8 @@ extern int early_irq_init(void); extern int arch_probe_nr_irqs(void); extern int arch_early_irq_init(void); -#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) +#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) || \ + defined(CONFIG_KPROBES) /* * We want to know which function is an entrypoint of a hardirq or a softirq. */
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