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| author | Björn Gustavsson <[email protected]> | 2017-06-26 10:30:54 +0200 |
|---|---|---|
| committer | Björn Gustavsson <[email protected]> | 2017-06-26 10:50:33 +0200 |
| commit | f405b07bc6136c76a016da67dc65e5c7ec9d8f9f (patch) | |
| tree | cac72d10b734fc0712997e06959518be5291579b | |
| parent | bd2752e3d2ec91572e4d0c2fb35951f8f6bdc9f6 (diff) | |
| download | otp-f405b07bc6136c76a016da67dc65e5c7ec9d8f9f.tar.gz otp-f405b07bc6136c76a016da67dc65e5c7ec9d8f9f.tar.bz2 otp-f405b07bc6136c76a016da67dc65e5c7ec9d8f9f.zip | |
Eliminate potential unsafe use of general destination
a3407eaa2104d6 eliminated the -gen_dest flag for macros in ops.tab.
It turns out that the new implementation (taking the address of the
X or X destination register) is unsafe if the destination is a Y
register and there can be a GC. The problem is that the address to
the Y register will change if there is a GC.
Fortunately, the few instructions in OTP 20 that have a general
destinations are safe. The put_list_ssd instruction never does a GC.
The bit syntax instructions that may do a GC will always store the
result to an X register.
To be completely sure, rewrite the destination register from 'd' to
'x' for the bit syntax instructions. That means that a bit syntax
instruction with a Y register destionation will abort the loading
if it is encountered.
| -rw-r--r-- | erts/emulator/beam/ops.tab | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/erts/emulator/beam/ops.tab b/erts/emulator/beam/ops.tab index cdf9cb58b9..44613c7d85 100644 --- a/erts/emulator/beam/ops.tab +++ b/erts/emulator/beam/ops.tab @@ -1174,9 +1174,9 @@ bs_get_binary2 Fail=f Ms=x Live=u Sz=sq Unit=u Flags=u Dst=d => \ %macro: i_bs_get_binary2 BsGetBinary_2 -fail_action %macro: i_bs_get_binary_all2 BsGetBinaryAll_2 -fail_action -i_bs_get_binary_imm2 f x I I I d -i_bs_get_binary2 f x I s I d -i_bs_get_binary_all2 f x I I d +i_bs_get_binary_imm2 f x I I I x +i_bs_get_binary2 f x I s I x +i_bs_get_binary_all2 f x I I x i_bs_get_binary_all_reuse x f I # Fetching float from binaries. @@ -1186,7 +1186,7 @@ bs_get_float2 Fail=f Ms=x Live=u Sz=s Unit=u Flags=u Dst=d => \ bs_get_float2 Fail=f Ms=x Live=u Sz=q Unit=u Flags=u Dst=d => jump Fail %macro: i_bs_get_float2 BsGetFloat2 -fail_action -i_bs_get_float2 f x I s I d +i_bs_get_float2 f x I s I x # Miscellanous |