Eric Lee / smarc-fsl-linux-kernel

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Commit ad05711cec12131e1277ce749a99d08ecf233aa7

Authored by David A. Long
Committed by Catalin Marinas
1 parent 7f1d642fbb

arm64: Remove stack duplicating code from jprobes 

Because the arm64 calling standard allows stacked function arguments to be
anywhere in the stack frame, do not attempt to duplicate the stack frame for
jprobes handler functions.

Documentation changes to describe this issue have been broken out into a
separate patch in order to simultaneously address them in other
architecture(s).

Signed-off-by: David A. Long <dave.long@linaro.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Showing 2 changed files with 5 additions and 28 deletions Side-by-side Diff

arch/arm64/include/asm/kprobes.h
Diff comments   View file @ ad05711
... ... @@ -22,7 +22,6 @@
22 22  
23 23 #define __ARCH_WANT_KPROBES_INSN_SLOT
24 24 #define MAX_INSN_SIZE 1
25   -#define MAX_STACK_SIZE 128
26 25  
27 26 #define flush_insn_slot(p) do { } while (0)
28 27 #define kretprobe_blacklist_size 0
... ... @@ -47,7 +46,6 @@
47 46 struct prev_kprobe prev_kprobe;
48 47 struct kprobe_step_ctx ss_ctx;
49 48 struct pt_regs jprobe_saved_regs;
50   - char jprobes_stack[MAX_STACK_SIZE];
51 49 };
52 50  
53 51 void arch_remove_kprobe(struct kprobe *);
arch/arm64/kernel/probes/kprobes.c
Diff comments   View file @ ad05711
... ... @@ -41,18 +41,6 @@
41 41 static void __kprobes
42 42 post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *);
43 43  
44   -static inline unsigned long min_stack_size(unsigned long addr)
45   -{
46   - unsigned long size;
47   -
48   - if (on_irq_stack(addr, raw_smp_processor_id()))
49   - size = IRQ_STACK_PTR(raw_smp_processor_id()) - addr;
50   - else
51   - size = (unsigned long)current_thread_info() + THREAD_START_SP - addr;
52   -
53   - return min(size, FIELD_SIZEOF(struct kprobe_ctlblk, jprobes_stack));
54   -}
55   -
56 44 static void __kprobes arch_prepare_ss_slot(struct kprobe *p)
57 45 {
58 46 /* prepare insn slot */
59 47  
60 48  
... ... @@ -489,20 +477,15 @@
489 477 {
490 478 struct jprobe *jp = container_of(p, struct jprobe, kp);
491 479 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
492   - long stack_ptr = kernel_stack_pointer(regs);
493 480  
494 481 kcb->jprobe_saved_regs = *regs;
495 482 /*
496   - * As Linus pointed out, gcc assumes that the callee
497   - * owns the argument space and could overwrite it, e.g.
498   - * tailcall optimization. So, to be absolutely safe
499   - * we also save and restore enough stack bytes to cover
500   - * the argument area.
  483 + * Since we can't be sure where in the stack frame "stacked"
  484 + * pass-by-value arguments are stored we just don't try to
  485 + * duplicate any of the stack. Do not use jprobes on functions that
  486 + * use more than 64 bytes (after padding each to an 8 byte boundary)
  487 + * of arguments, or pass individual arguments larger than 16 bytes.
501 488 */
502   - kasan_disable_current();
503   - memcpy(kcb->jprobes_stack, (void *)stack_ptr,
504   - min_stack_size(stack_ptr));
505   - kasan_enable_current();
506 489  
507 490 instruction_pointer_set(regs, (unsigned long) jp->entry);
508 491 preempt_disable();
... ... @@ -554,10 +537,6 @@
554 537 }
555 538 unpause_graph_tracing();
556 539 *regs = kcb->jprobe_saved_regs;
557   - kasan_disable_current();
558   - memcpy((void *)stack_addr, kcb->jprobes_stack,
559   - min_stack_size(stack_addr));
560   - kasan_enable_current();
561 540 preempt_enable_no_resched();
562 541 return 1;
563 542 }