diff options
Diffstat (limited to 'arch/arm64/kernel/probes/kprobes.c')
| -rw-r--r-- | arch/arm64/kernel/probes/kprobes.c | 67 |
1 files changed, 20 insertions, 47 deletions
diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index bf9768588288..f5077ea7af6d 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -19,7 +19,7 @@ #include <linux/kasan.h> #include <linux/kernel.h> #include <linux/kprobes.h> -#include <linux/module.h> +#include <linux/extable.h> #include <linux/slab.h> #include <linux/stop_machine.h> #include <linux/stringify.h> @@ -31,7 +31,7 @@ #include <asm/insn.h> #include <asm/uaccess.h> #include <asm/irq.h> -#include <asm-generic/sections.h> +#include <asm/sections.h> #include "decode-insn.h" @@ -41,18 +41,6 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); static void __kprobes post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *); -static inline unsigned long min_stack_size(unsigned long addr) -{ - unsigned long size; - - if (on_irq_stack(addr, raw_smp_processor_id())) - size = IRQ_STACK_PTR(raw_smp_processor_id()) - addr; - else - size = (unsigned long)current_thread_info() + THREAD_START_SP - addr; - - return min(size, FIELD_SIZEOF(struct kprobe_ctlblk, jprobes_stack)); -} - static void __kprobes arch_prepare_ss_slot(struct kprobe *p) { /* prepare insn slot */ @@ -178,13 +166,18 @@ static void __kprobes set_current_kprobe(struct kprobe *p) } /* - * The D-flag (Debug mask) is set (masked) upon debug exception entry. - * Kprobes needs to clear (unmask) D-flag -ONLY- in case of recursive - * probe i.e. when probe hit from kprobe handler context upon - * executing the pre/post handlers. In this case we return with - * D-flag clear so that single-stepping can be carried-out. - * - * Leave D-flag set in all other cases. + * When PSTATE.D is set (masked), then software step exceptions can not be + * generated. + * SPSR's D bit shows the value of PSTATE.D immediately before the + * exception was taken. PSTATE.D is set while entering into any exception + * mode, however software clears it for any normal (none-debug-exception) + * mode in the exception entry. Therefore, when we are entering into kprobe + * breakpoint handler from any normal mode then SPSR.D bit is already + * cleared, however it is set when we are entering from any debug exception + * mode. + * Since we always need to generate single step exception after a kprobe + * breakpoint exception therefore we need to clear it unconditionally, when + * we become sure that the current breakpoint exception is for kprobe. */ static void __kprobes spsr_set_debug_flag(struct pt_regs *regs, int mask) @@ -257,10 +250,7 @@ static void __kprobes setup_singlestep(struct kprobe *p, set_ss_context(kcb, slot); /* mark pending ss */ - if (kcb->kprobe_status == KPROBE_REENTER) - spsr_set_debug_flag(regs, 0); - else - WARN_ON(regs->pstate & PSR_D_BIT); + spsr_set_debug_flag(regs, 0); /* IRQs and single stepping do not mix well. */ kprobes_save_local_irqflag(kcb, regs); @@ -345,8 +335,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr) BUG(); kernel_disable_single_step(); - if (kcb->kprobe_status == KPROBE_REENTER) - spsr_set_debug_flag(regs, 1); if (kcb->kprobe_status == KPROBE_REENTER) restore_previous_kprobe(kcb); @@ -469,9 +457,6 @@ kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr) kprobes_restore_local_irqflag(kcb, regs); kernel_disable_single_step(); - if (kcb->kprobe_status == KPROBE_REENTER) - spsr_set_debug_flag(regs, 1); - post_kprobe_handler(kcb, regs); } @@ -489,20 +474,15 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) { struct jprobe *jp = container_of(p, struct jprobe, kp); struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - long stack_ptr = kernel_stack_pointer(regs); kcb->jprobe_saved_regs = *regs; /* - * As Linus pointed out, gcc assumes that the callee - * owns the argument space and could overwrite it, e.g. - * tailcall optimization. So, to be absolutely safe - * we also save and restore enough stack bytes to cover - * the argument area. + * Since we can't be sure where in the stack frame "stacked" + * pass-by-value arguments are stored we just don't try to + * duplicate any of the stack. Do not use jprobes on functions that + * use more than 64 bytes (after padding each to an 8 byte boundary) + * of arguments, or pass individual arguments larger than 16 bytes. */ - kasan_disable_current(); - memcpy(kcb->jprobes_stack, (void *)stack_ptr, - min_stack_size(stack_ptr)); - kasan_enable_current(); instruction_pointer_set(regs, (unsigned long) jp->entry); preempt_disable(); @@ -554,19 +534,12 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) } unpause_graph_tracing(); *regs = kcb->jprobe_saved_regs; - kasan_disable_current(); - memcpy((void *)stack_addr, kcb->jprobes_stack, - min_stack_size(stack_addr)); - kasan_enable_current(); preempt_enable_no_resched(); return 1; } bool arch_within_kprobe_blacklist(unsigned long addr) { - extern char __idmap_text_start[], __idmap_text_end[]; - extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[]; - if ((addr >= (unsigned long)__kprobes_text_start && addr < (unsigned long)__kprobes_text_end) || (addr >= (unsigned long)__entry_text_start && |