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@xxxxxxxxxx> Reported-by: Francis Deslauriers <francis.deslauriers@xxxxxxxxxxxx> Tested-by: Francis Deslauriers <francis.deslauriers@xxxxxxxxxxxx> --- arch/x86/kernel/kprobes/opt.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index 69ea0bc1cfa3..4f98aad38237 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -39,6 +39,7 @@ #include <asm/insn.h> #include <asm/debugreg.h> #include <asm/set_memory.h> +#include <asm/sections.h> #include "common.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. */
