diff options
Diffstat (limited to 'crypto/perlasm/x86_64-xlate.pl')
| -rwxr-xr-x | crypto/perlasm/x86_64-xlate.pl | 29 |
1 files changed, 17 insertions, 12 deletions
diff --git a/crypto/perlasm/x86_64-xlate.pl b/crypto/perlasm/x86_64-xlate.pl index 1ae2442..dd8afe7 100755 --- a/crypto/perlasm/x86_64-xlate.pl +++ b/crypto/perlasm/x86_64-xlate.pl @@ -1072,6 +1072,7 @@ close STDOUT; # movq -16(%rcx),%rbx # movq -8(%rcx),%r15 # movq %rcx,%rsp # restore original rsp +# magic_epilogue: # ret # .size function,.-function # @@ -1084,11 +1085,16 @@ close STDOUT; # EXCEPTION_DISPOSITION handler (EXCEPTION_RECORD *rec,ULONG64 frame, # CONTEXT *context,DISPATCHER_CONTEXT *disp) # { ULONG64 *rsp = (ULONG64 *)context->Rax; -# if (context->Rip >= magic_point) -# { rsp = ((ULONG64 **)context->Rsp)[0]; -# context->Rbp = rsp[-3]; -# context->Rbx = rsp[-2]; -# context->R15 = rsp[-1]; +# ULONG64 rip = context->Rip; +# +# if (rip >= magic_point) +# { rsp = (ULONG64 *)context->Rsp; +# if (rip < magic_epilogue) +# { rsp = (ULONG64 *)rsp[0]; +# context->Rbp = rsp[-3]; +# context->Rbx = rsp[-2]; +# context->R15 = rsp[-1]; +# } # } # context->Rsp = (ULONG64)rsp; # context->Rdi = rsp[1]; @@ -1180,13 +1186,12 @@ close STDOUT; # instruction and reflecting it in finer grade unwind logic in handler. # After all, isn't it why it's called *language-specific* handler... # -# Attentive reader can notice that exceptions would be mishandled in -# auto-generated "gear" epilogue. Well, exception effectively can't -# occur there, because if memory area used by it was subject to -# segmentation violation, then it would be raised upon call to the -# function (and as already mentioned be accounted to caller, which is -# not a problem). If you're still not comfortable, then define tail -# "magic point" just prior ret instruction and have handler treat it... +# SE handlers are also involved in unwinding stack when executable is +# profiled or debugged. Profiling implies additional limitations that +# are too subtle to discuss here. For now it's sufficient to say that +# in order to simplify handlers one should either a) offload original +# %rsp to stack (like discussed above); or b) if you have a register to +# spare for frame pointer, choose volatile one. # # (*) Note that we're talking about run-time, not debug-time. Lack of # unwind information makes debugging hard on both Windows and |