Messages in this thread | | | Date | Thu, 10 Sep 2009 07:16:48 +0200 | From | Ingo Molnar <> | Subject | Re: [GIT PULL] Xen bugfixes |
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* Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> Hi, > > Here's 3 patches which fix two Xen PV spinlock bugs, and makes > CONFIG_CC_STACKPROTECTOR work on both 32- and 64-bit. > > The spinlock bugs are both rare races: > - lock can briefly hold the lock while interrupts are enabled, allowing an ISR to deadlock > - unlock doesn't enforce CPU memory ordering between the actual unlock write and the check > to see if there are any pending waiters, so it can end up deciding there's nobody to > kick on unlock, leaving another CPU hanging. It needs a full mb() to guarantee the correct > ordering. > > The stack-protector fix bites the bullet and does a full GDT setup > early so that we can load %gs for the stack-protector canary > segment on i386. This also removes the assumption that the > initial percpu %fs segment has a zero base. > > x86-64 still just needs the GS_BASE MSR written, but that now > happens using the same code as i386 rather than being special > cased. > > Thanks, > J > > The following changes since commit e07cccf4046978df10f2e13fe2b99b2f9b3a65db: > Linus Torvalds (1): > Linux 2.6.31-rc9 > > are available in the git repository at: > > git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git bugfix > > Jeremy Fitzhardinge (2): > xen: make -fstack-protector work under Xen > xen: only enable interrupts while actually blocking for spinlock > > Yang Xiaowei (1): > xen: use stronger barrier after unlocking lock > > arch/x86/mm/Makefile | 4 ++ > arch/x86/xen/Makefile | 2 + > arch/x86/xen/enlighten.c | 131 +++++++++++++++++++++++++++++++++++++++------- > arch/x86/xen/smp.c | 1 + > arch/x86/xen/spinlock.c | 28 ++++++---- > drivers/xen/Makefile | 3 + > 6 files changed, 140 insertions(+), 29 deletions(-)
Pulled, thanks a lot Jeremy!
A few comments:
> +# Make sure __phys_addr has no stackprotector > +nostackp := $(call cc-option, -fno-stack-protector) > +CFLAGS_ioremap.o := $(nostackp) > +
Sure we could move __phys_addr into its own file and thus avoid turning off stackprotector for the rest of ioremap.c?
> --- a/arch/x86/xen/Makefile > +++ b/arch/x86/xen/Makefile > @@ -8,6 +8,7 @@ endif > # Make sure early boot has no stackprotector > nostackp := $(call cc-option, -fno-stack-protector) > CFLAGS_enlighten.o := $(nostackp) > +CFLAGS_mmu.o := $(nostackp)
A similar argument could be made here - what proportion of mmu.c is affected?
Also, once the commits have hit upstream feel free bounce them to stable@kernel.org - they dont have Cc: <stable@kernel.org> tags for automatic back-merging requests. The fixes narrowly missed v2.6.31.
Ingo
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