[lldb-dev] [PATCH] Incorrect register map for Linux 32-bit - Correction supplied

Matthew Gardiner mg11 at csr.com
Fri Feb 14 03:39:07 PST 2014


The register map in RegisterContextLinux_i386.cpp is in disagreement 
with that seen in /usr/include/sys/user.h. The result is that offset 
calculations for the dr0-dr7 are incorrect. I've had a look at the 
source and determined that this can't be fixed portably (i.e. for 
32/64-bit) with:

FXSAVE i387;

since FXSAVE deploys a union and thus the size of the struct would be 
the same in either architecture, which would be undesirable. I have 
fixed this on my system with:

Index: source/Plugins/Process/POSIX/RegisterContextLinux_i386.cpp
--- source/Plugins/Process/POSIX/RegisterContextLinux_i386.cpp	(revision 
+++ source/Plugins/Process/POSIX/RegisterContextLinux_i386.cpp	(working 
@@ -34,11 +34,23 @@
      uint32_t ss;

+struct FPR_i386
+  long int cwd;
+  long int swd;
+  long int twd;
+  long int fip;
+  long int fcs;
+  long int foo;
+  long int fos;
+  long int st_space [20];
  struct UserArea
      GPR      regs;          // General purpose registers.
      int32_t  fpvalid;       // True if FPU is being used.
-    FXSAVE   i387;          // FPU registers.
+    FPR_i386   i387;        // FPU registers.
      uint32_t tsize;         // Text segment size.
      uint32_t dsize;         // Data segment size.
      uint32_t ssize;         // Stack segment size.

That is, by repetition of the linux FPR area within the lldb codebase. 
(I could not use the more obvious FPR as my struct name, as it collided 
with a previous use of the name).

Would someone be able to view/consider/submit my patch?


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