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caml_callback2 crashes on aarch64 #6489

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vicuna opened this issue Jul 15, 2014 · 4 comments
Closed

caml_callback2 crashes on aarch64 #6489

vicuna opened this issue Jul 15, 2014 · 4 comments
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@vicuna
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@vicuna vicuna commented Jul 15, 2014

Original bug ID: 6489
Reporter: Richard Jones
Assigned to: @mshinwell
Status: closed (set by @xavierleroy on 2015-12-11T18:28:12Z)
Resolution: fixed
Priority: normal
Severity: crash
Version: 4.02.0+beta1 / +rc1
Fixed in version: 4.02.0+dev
Category: back end (clambda to assembly)

Bug description

caml_callback2 segfaults when called, on aarch64.

Steps to reproduce

Compile the attached program using:

ocamlopt.opt callback.c callback_ml.ml -o callback

Then run it using:

./callback

The output is:

$ ./callback
f1 (100)
Segmentation fault

Note that caml_callback and caml_callback3 are fine, it's just caml_callback2 which fails.

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@vicuna

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@vicuna vicuna commented Jul 15, 2014

Comment author: Richard Jones

Well, that's not quite true. All of the caml_callback* functions cause heap corruption. If you call Gc.compact () after any of them, then it will segfault. Only caml_callback2 segfaults on its own without any help.

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@vicuna vicuna commented Jul 15, 2014

Comment author: Richard Jones

Please ignore the previous comment, as I made a mistake in my test. Only caml_callback2 is problematic.

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@vicuna vicuna commented Jul 15, 2014

Comment author: Richard Jones

This is caused by a missing close comment */ here:

https://github.com/ocaml/ocaml/blob/4.02/asmrun/arm64.S#L481

The fix is:

--- a/asmrun/arm64.S
+++ b/asmrun/arm64.S
@@ -478,7 +478,7 @@ caml_callback2_exn:
/* Initial shuffling of arguments (x0 = closure, x1 = arg1, x2 = arg2) /
mov TMP, x0
mov x0, x1 /
x0 = first arg */

  •    mov     x1, x2          /* x1 = second arg
    
  •    mov     x1, x2          /* x1 = second arg */
       mov     x2, TMP         /* x2 = closure environment */
       ADDRGLOBAL(ARG, caml_apply2)
       b       .Ljump_to_caml
    
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@vicuna vicuna commented Jul 16, 2014

Comment author: @mshinwell

Very good. Thanks for the fix. Committed to 4.02 and trunk.

@vicuna vicuna closed this Dec 11, 2015
@vicuna vicuna added the back-end label Mar 14, 2019
@vicuna vicuna added the bug label Mar 20, 2019
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