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authorBjörn Gustavsson <[email protected]>2015-06-29 13:24:31 +0200
committerBjörn Gustavsson <[email protected]>2015-07-03 14:28:03 +0200
commitdfe1c58c504531361fa3f8ed874238a9ff552640 (patch)
tree42dc0c14edb059bfb6e331ddf81f6f1f41aa3bae /erts/emulator
parent26f1810479a837ab338e7a9e3aef027a9e4b098d (diff)
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beam_makeops: Eliminate crash because of unsafe packing
Consider an hypothetical instruction: do_something x x c The loader would crash if we tried to load an instance of the instruction with the last operand referencing a literal: {do_something,{x,0},{x,1},{literal,{a,b,c}}} Teach beam_makeops to turn off packing for such unsafe instructions.
Diffstat (limited to 'erts/emulator')
-rwxr-xr-xerts/emulator/utils/beam_makeops13
1 files changed, 13 insertions, 0 deletions
diff --git a/erts/emulator/utils/beam_makeops b/erts/emulator/utils/beam_makeops
index e90ed94187..7c94546ea4 100755
--- a/erts/emulator/utils/beam_makeops
+++ b/erts/emulator/utils/beam_makeops
@@ -1057,6 +1057,7 @@ sub do_pack {
my($packable_args) = 0;
my @is_packable; # Packability (boolean) for each argument.
my $wide_packing = 0;
+ my(@orig_args) = @args;
#
# Count the number of packable arguments. If we encounter any 's' or 'd'
@@ -1077,6 +1078,18 @@ sub do_pack {
}
} elsif ($arg =~ /^[sd]/) {
return ('', '', @args);
+ } elsif ($arg =~ /^[scq]/ and $packable_args > 0) {
+ # When packing, this operand will be picked up from the
+ # code array, put onto the packing stack, and later put
+ # back into a different location in the code. The problem
+ # is that if this operand is a literal, the original
+ # location in the code would have been remembered in a
+ # literal patch. For packing to work, we would have to
+ # adjust the position in the literal patch. For the
+ # moment, adding additional instructions to the packing
+ # engine to handle this does not seem worth it, so we will
+ # just turn off packing.
+ return ('', '', @args);
} else {
push @is_packable, 0;
}