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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Jason Wessel <jason.wessel@windriver.com>
Cc: linux-kernel@vger.kernel.org, kgdb-bugreport@lists.sourceforge.net
Subject: Re: [PATCH 2/3] kgdb,i386: use address that SP register points to in the exception frame
Date: Fri, 15 May 2009 08:16:26 -0700 (PDT)	[thread overview]
Message-ID: <alpine.LFD.2.01.0905150814180.3343@localhost.localdomain> (raw)
In-Reply-To: <1242393479-19351-3-git-send-email-jason.wessel@windriver.com>



On Fri, 15 May 2009, Jason Wessel wrote:
>
> The treatment of the SP register is different on x86_64 and i386.
> This is a regression fix that lived outside the mainline kernel from
> 2.6.27 to now.  The regression was a result of the original merge
> consolidation of the i386 and x86_64 archs to x86.
> 
> The incorrectly reported SP on i386 prevented stack tracebacks from
> working correctly in gdb.

Is this only ever used for kernel register state?

Because in the _general_ case, the code should likely be something like

	if (user_mode_vm(regs)) {
		gdb_regs[GDB_SS] = regs->ss;
		gdb_regs[GDB_SP] = regs->sp;
	} else {
		gdb_regs[GDB_SS] = __KERNEL_DS;
		gdb_regs[GDB_SP] = (unsigned long)&regs->sp
	}

if the 'regs' contents can ever point to user mode state.

		Linus

  parent reply	other threads:[~2009-05-15 15:17 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-15 13:17 [git pull] kgdb 2.6.30-rc5 regression fixes Jason Wessel
2009-05-15 13:17 ` [PATCH 1/3] sysrq, intel_fb: fix sysrq g collision Jason Wessel
2009-05-15 13:17   ` [PATCH 2/3] kgdb,i386: use address that SP register points to in the exception frame Jason Wessel
2009-05-15 13:17     ` [PATCH 3/3] kgdb: gdb documentation fix Jason Wessel
2009-05-15 15:16     ` Linus Torvalds [this message]
2009-05-15 19:20       ` [PATCH 2/3] kgdb,i386: use address that SP register points to in the exception frame Jason Wessel

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