Fix 32-bit thread debugging on x86_64

From: Daniel Jacobowitz
Date: Sun Jul 31 2005 - 15:09:03 EST


The IA32 ptrace emulation currently returns the wrong registers for
fs/gs; it's returning what x86_64 calls gs_base. We need regs.gsindex
in order for GDB to correctly locate the TLS area. Without this patch,
the 32-bit GDB testsuite bombs on a 64-bit kernel. With it, results
look about like I'd expect, although there are still a handful of
kernel-related failures (vsyscall related?).

Signed-off-by: Daniel Jacobowitz <dan@xxxxxxxxxxxxxxxx>

diff -r -p -u z/linux-2.6.11/arch/x86_64/ia32/ptrace32.c linux-2.6.11/arch/x86_64/ia32/ptrace32.c
--- linux-2.6.12.3.orig/arch/x86_64/ia32/ptrace32.c 2005-03-02 02:37:52.000000000 -0500
+++ linux-2.6.12.3/arch/x86_64/ia32/ptrace32.c 2005-07-31 15:29:48.000000000 -0400
@@ -43,11 +43,11 @@ static int putreg32(struct task_struct *
switch (regno) {
case offsetof(struct user32, regs.fs):
if (val && (val & 3) != 3) return -EIO;
- child->thread.fs = val & 0xffff;
+ child->thread.fsindex = val & 0xffff;
break;
case offsetof(struct user32, regs.gs):
if (val && (val & 3) != 3) return -EIO;
- child->thread.gs = val & 0xffff;
+ child->thread.gsindex = val & 0xffff;
break;
case offsetof(struct user32, regs.ds):
if (val && (val & 3) != 3) return -EIO;
@@ -138,10 +138,10 @@ static int getreg32(struct task_struct *

switch (regno) {
case offsetof(struct user32, regs.fs):
- *val = child->thread.fs;
+ *val = child->thread.fsindex;
break;
case offsetof(struct user32, regs.gs):
- *val = child->thread.gs;
+ *val = child->thread.gsindex;
break;
case offsetof(struct user32, regs.ds):
*val = child->thread.ds;

--
Daniel Jacobowitz
CodeSourcery, LLC
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/