Merge tag 'drm/tegra/for-4.8-rc4' of git://anongit.freedesktop.org/tegra/linux into...

[cascardo/linux.git] / arch / arm64 / kernel / probes / kprobes.c

diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
index bf97685..c6b0f40 100644 (file)
--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -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 */
@@ -489,20 +477,15 @@ 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();
@@ -554,10 +537,6 @@ 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;
 }