[Linux-ia64] [PATCH] IA-32 emulation patch: ptrace get_FPREGS bug fix

[Linux-ia64] [PATCH] IA-32 emulation patch: ptrace get_FPREGS bug fix

[Pallipadi, Venkatesh]

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A bug-fix in IA-32 emulation ptrace code. The bug originally got
introduced with the addition of FPXREGS support in ptrace.

The bug is in ptrace get/set FPREGS routine. gdb by default will not use
FPREGS routines when FPXREGS routines are supported.  So we may not see
this bug during normal gdb operations. But, if gdb (or any other app)
directly tries to get/set FPREGS (probably an old version of gdb), it
will end with an segmentation fault due to this bug.

Attached patch fixes the issue. The patch is taken against 2.5.69. But
it applies to 2.4 tree as well. 

Please let me know, if you need any more information on this.

Thanks,
-Venkatesh

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diff -urN linux-2.5.69/arch/ia64/ia32/sys_ia32.c linux-2.5.69-fix/arch/ia64/ia32/sys_ia32.c
--- linux-2.5.69/arch/ia64/ia32/sys_ia32.c	Mon May 12 14:20:23 2003
+++ linux-2.5.69-fix/arch/ia64/ia32/sys_ia32.c	Fri May 30 11:26:25 2003
@@ -1860,7 +1860,7 @@
 	ptp = ia64_task_regs(tsk);
 	tos = (tsk->thread.fsr >> 11) & 7;
 	for (i = 0; i < 8; i++)
-		put_fpreg(i, (struct _fpreg_ia32 *)&save->st_space[4*i], ptp, swp, tos);
+		put_fpreg(i, &save->st_space[i], ptp, swp, tos);
 	return 0;
 }
 
@@ -1893,7 +1893,7 @@
 	ptp = ia64_task_regs(tsk);
 	tos = (tsk->thread.fsr >> 11) & 7;
 	for (i = 0; i < 8; i++)
-		get_fpreg(i, (struct _fpreg_ia32 *)&save->st_space[4*i], ptp, swp, tos);
+		get_fpreg(i, &save->st_space[i], ptp, swp, tos);
 	return 0;
 }
 
diff -urN linux-2.5.69/include/asm-ia64/ia32.h linux-2.5.69-fix/include/asm-ia64/ia32.h
--- linux-2.5.69/include/asm-ia64/ia32.h	Mon May 12 14:20:32 2003
+++ linux-2.5.69-fix/include/asm-ia64/ia32.h	Fri May 30 11:26:25 2003
@@ -108,7 +108,8 @@
 	int	fcs;
 	int	foo;
 	int	fos;
-	int	st_space[20];	/* 8*10 bytes for each FP-reg = 80 bytes */
+	/* 8*10 bytes for each FP-reg = 80 bytes */
+	struct _fpreg_ia32 	st_space[8];
 };
 
 struct ia32_user_fxsr_struct {

Re: [Linux-ia64] [PATCH] IA-32 emulation patch: ptrace get_FPREGS bug fix

[David Mosberger]

>>>>> On Fri, 30 May 2003 18:19:02 -0700, "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com> said:

  Venkatesh> A bug-fix in IA-32 emulation ptrace code. The bug
  Venkatesh> originally got introduced with the addition of FPXREGS
  Venkatesh> support in ptrace.

Applied, thanks.

	--david

Re: [Linux-ia64] [PATCH] IA-32 emulation patch: ptrace get_FPREGS bug fix

[Bjorn Helgaas]

On Friday 30 May 2003 7:19 pm, Pallipadi, Venkatesh wrote:
> A bug-fix in IA-32 emulation ptrace code. The bug originally got
> introduced with the addition of FPXREGS support in ptrace.

I applied this for 2.4.  Thanks!