Messages in this thread | | | Date | Fri, 25 Sep 2009 18:56:38 -0400 | Subject | Re: [GIT PULL] x86: unify sys_iopl | From | Brian Gerst <> |
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The correct fix is to move set_iopl_mask into do_iopl. sys_iopl should only be a wrapper around do_iopl to manage the different calling convention used by 32-bit and 64-bit.
On Fri, Sep 25, 2009 at 6:05 PM, Jeremy Fitzhardinge <jeremy@goop.org> wrote: > Hi Ingo, > > The x86-64 implementation of iopl was buggy because it never ended up calling > set_iopl_mask(). This had no effect on native sys_iopl (because set_iopl_mask > is normally no-op on 64-bit), but it ended up never calling the pvop, which caused > iopl to have no effect on 64-bit Xen guests. > > The two functions are needlessly different anyway. This patch just unifies them > into a single function which is mostly derived from the 32-bit version. > > Thanks, > J > > The following changes since commit c44c9ec0f38b939b3200436e3aa95c1aa83c41c7: > Jeremy Fitzhardinge (1): > x86: split NX setup into separate file to limit unstack-protected code > > are available in the git repository at: > > git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git bugfix > > Jeremy Fitzhardinge (1): > x86: unify sys_iopl > > arch/x86/include/asm/syscalls.h | 8 +++----- > arch/x86/kernel/ioport.c | 11 ++--------- > 2 files changed, 5 insertions(+), 14 deletions(-) > > From 8dbb1d168eb8be6bf43d123fdfb3ba3b03762e62 Mon Sep 17 00:00:00 2001 > From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> > Date: Wed, 23 Sep 2009 16:35:24 -0700 > Subject: [PATCH] x86: unify sys_iopl > > The 32 and 64-bit versions of sys_iopl were needlessly different: > - The 32-bit version ignored its function argument and directly > fetched the parameter from struct regs, presumably code dating > from the neolithic era. > - The 64-bit version never called set_iopl_mask(). Usually this > is a no-op for 64-bit, but it is also a pvop, which meant that > that iopl never worked for 64-bit guests under Xen. > - Both versions use the archaic style of getting pt_regs passed > to them. We can get the current pt_regs with task_pt_regs, which > avoids worrying about the fine details of stack layout. > > We can use the body of the 32-bit function with a few small > adjustments to the function definition. > > Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> > > diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h > index 372b76e..5336ce2 100644 > --- a/arch/x86/include/asm/syscalls.h > +++ b/arch/x86/include/asm/syscalls.h > @@ -33,11 +33,11 @@ long sys_rt_sigreturn(struct pt_regs *); > asmlinkage int sys_set_thread_area(struct user_desc __user *); > asmlinkage int sys_get_thread_area(struct user_desc __user *); > > -/* X86_32 only */ > -#ifdef CONFIG_X86_32 > /* kernel/ioport.c */ > -long sys_iopl(struct pt_regs *); > +asmlinkage long sys_iopl(unsigned int); > > +/* X86_32 only */ > +#ifdef CONFIG_X86_32 > /* kernel/process_32.c */ > int sys_clone(struct pt_regs *); > int sys_execve(struct pt_regs *); > @@ -70,8 +70,6 @@ int sys_vm86(struct pt_regs *); > #else /* CONFIG_X86_32 */ > > /* X86_64 only */ > -/* kernel/ioport.c */ > -asmlinkage long sys_iopl(unsigned int, struct pt_regs *); > > /* kernel/process_64.c */ > asmlinkage long sys_clone(unsigned long, unsigned long, > diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c > index 99c4d30..bad4f22 100644 > --- a/arch/x86/kernel/ioport.c > +++ b/arch/x86/kernel/ioport.c > @@ -119,11 +119,10 @@ static int do_iopl(unsigned int level, struct pt_regs *regs) > return 0; > } > > -#ifdef CONFIG_X86_32 > -long sys_iopl(struct pt_regs *regs) > +asmlinkage long sys_iopl(unsigned int level) > { > - unsigned int level = regs->bx; > struct thread_struct *t = ¤t->thread; > + struct pt_regs *regs = task_pt_regs(current); > int rc; > > rc = do_iopl(level, regs); > @@ -135,9 +134,3 @@ long sys_iopl(struct pt_regs *regs) > out: > return rc; > } > -#else > -asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs) > -{ > - return do_iopl(level, regs); > -} > -#endif > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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