[Crash-utility] 32 bit linux-2.6.24-git8 user_regs_struct change breaks opening kdump crashfiles

[Dave Anderson]

----- "Joe Porter" <joe.porter at ccur.com> wrote:

> Hello crash,
> 
> The user_regs_struct was redefined in
> linux-2.6.24-git8/include/asm-x86/user_32.h.
> 
> This results in the following error when opening 32 bit kdump
> crashfiles:
> -------------------------------------------------------------------------
> please wait... (determining panic task)
> crash: invalid structure member offset: user_regs_struct_ebp
>        FILE: netdump.c  LINE: 687  FUNCTION: get_netdump_panic_task()
> 
> [/sbin/crash] error trace: 80e09f4 => 8154159 => 814fc3f => 813ec75
> 
>   813ec75: OFFSET_verify+126
>   814fc3f: get_netdump_panic_task+1196
>   8154159: get_kdump_panic_task+11
>   80e09f4: get_dumpfile_panic_task+153
> --------------------------------------------------------------------
> 
> I've inserted a patch to crash-4.0-7.4/x86.c that fixes this for all
> linux-2.6.24-git8
> and later kernels (2.6.25 -> 2.6.28-rc5).  I've also inserted the
> kernel change that
> caused the breakage.
> 
> The fix is bad because it breaks all kernels <= linux-2.6.24-git7.  
> 
> A better fix would be backward and forward compatible with all
> kernels, but since there
> was a lot of hardwired code revolving around the old 32 bit
> user_regs_struct I thought I
> would just submit this patch to expose the problem and maybe look for
> a better fix in the
> next crash update.

Right -- it wouldn't be a "better fix", but rather the "only fix"
that's going to be acceptable.  

Does the new kernel that has the name changes end up using the
initial attempts to set the size, esp and ebp offsets?  Or does
it always end up using the "if (!VALID_STRUCT())" section?  It's
only going to use one or the other, depending upon whether the
user_regs_struct gets exported-to/included-in the debuginfo data.

Dave

> 
> thx, joe
> 
> --- crash-4.0-7.4.orig/x86.c	2008-10-14 09:35:40.000000000 -0400
> +++ crash-4.0-7.4/x86.c	2008-11-17 13:37:40.000000000 -0500
> @@ -1774,29 +1774,39 @@
>  			machdep->flags |= OMIT_FRAME_PTR;
>  		STRUCT_SIZE_INIT(user_regs_struct, "user_regs_struct");
>  		MEMBER_OFFSET_INIT(user_regs_struct_ebp,
> -			"user_regs_struct", "ebp");
> +			"user_regs_struct", "bp");
>  		MEMBER_OFFSET_INIT(user_regs_struct_esp,
> -			"user_regs_struct", "esp");
> +			"user_regs_struct", "sp");
>  		if (!VALID_STRUCT(user_regs_struct)) {
>  			/*  Use this hardwired version -- sometimes the 
>  			 *  debuginfo doesn't pick this up even though
>  			 *  it exists in the kernel; it shouldn't change.
>  			 */
>  			struct x86_user_regs_struct {
> -			        long ebx, ecx, edx, esi, edi, ebp, eax;
> -			        unsigned short ds, __ds, es, __es;
> -			        unsigned short fs, __fs, gs, __gs;
> -			        long orig_eax, eip;
> -			        unsigned short cs, __cs;
> -			        long eflags, esp;
> -			        unsigned short ss, __ss;
> +				unsigned long   bx;
> +				unsigned long   cx;
> +				unsigned long   dx;
> +				unsigned long   si;
> +				unsigned long   di;
> +				unsigned long   bp;
> +				unsigned long   ax;
> +				unsigned long   ds;
> +				unsigned long   es;
> +				unsigned long   fs;
> +				unsigned long   gs;
> +				unsigned long   orig_ax;
> +				unsigned long   ip;
> +				unsigned long   cs;
> +				unsigned long   flags;
> +				unsigned long   sp;
> +				unsigned long   ss;
>  			};
>  			ASSIGN_SIZE(user_regs_struct) = 
>  				sizeof(struct x86_user_regs_struct);
>  			ASSIGN_OFFSET(user_regs_struct_ebp) =
> -				offsetof(struct x86_user_regs_struct, ebp);
> +				offsetof(struct x86_user_regs_struct, bp);
>  			ASSIGN_OFFSET(user_regs_struct_esp) =
> -				offsetof(struct x86_user_regs_struct, esp);
> +				offsetof(struct x86_user_regs_struct, sp);
>  		}
>  		MEMBER_OFFSET_INIT(thread_struct_cr3, "thread_struct", "cr3");
>  		STRUCT_SIZE_INIT(cpuinfo_x86, "cpuinfo_x86");
> 
> --------------------------------------------------------------------------------
> 
> --- linux-2.6.24-git7/include/asm-x86/user_32.h 2008-01-24
> 17:58:37.000000000 -0500
> +++ linux-2.6.24-git8/include/asm-x86/user_32.h 2008-11-11
> 18:56:13.000000000 -0500
> @@ -75,13 +75,23 @@
>   * doesn't use the extra segment registers)
>   */
>  struct user_regs_struct {
> -       long ebx, ecx, edx, esi, edi, ebp, eax;
> -       unsigned short ds, __ds, es, __es;
> -       unsigned short fs, __fs, gs, __gs;
> -       long orig_eax, eip;
> -       unsigned short cs, __cs;
> -       long eflags, esp;
> -       unsigned short ss, __ss;
> +       unsigned long   bx;
> +       unsigned long   cx;
> +       unsigned long   dx;
> +       unsigned long   si;
> +       unsigned long   di;
> +       unsigned long   bp;
> +       unsigned long   ax;
> +       unsigned long   ds;
> +       unsigned long   es;
> +       unsigned long   fs;
> +       unsigned long   gs;
> +       unsigned long   orig_ax;
> +       unsigned long   ip;
> +       unsigned long   cs;
> +       unsigned long   flags;
> +       unsigned long   sp;
> +       unsigned long   ss;
>  };
> 
>  /* When the kernel dumps core, it starts by dumping the user struct
> -
> 
> --
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