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authorAndy Lutomirski <luto@amacapital.net>2015-03-05 19:19:02 -0800
committerIngo Molnar <mingo@kernel.org>2015-03-06 08:32:57 +0100
commit8ef46a672a7d852709561d10672b6eaa8a4acd82 (patch)
tree1911a360e3e1f29dbfd38f89b87f0d27269472d4 /arch/x86/lguest
parent5eca7453d61003bf886992388f8cb407e6f0d051 (diff)
downloadlinux-8ef46a672a7d852709561d10672b6eaa8a4acd82.tar.bz2
x86/asm/entry: Add this_cpu_sp0() to read sp0 for the current cpu
We currently store references to the top of the kernel stack in multiple places: kernel_stack (with an offset) and init_tss.x86_tss.sp0 (no offset). The latter is defined by hardware and is a clean canonical way to find the top of the stack. Add an accessor so we can start using it. This needs minor paravirt tweaks. On native, sp0 defines the top of the kernel stack and is therefore always correct. On Xen and lguest, the hypervisor tracks the top of the stack, but we want to start reading sp0 in the kernel. Fixing this is simple: just update our local copy of sp0 as well as the hypervisor's copy on task switches. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/8d675581859712bee09a055ed8f785d80dac1eca.1425611534.git.luto@amacapital.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/lguest')
-rw-r--r--arch/x86/lguest/boot.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index ac4453d8520e..8561585ee2c6 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -1076,6 +1076,7 @@ static void lguest_load_sp0(struct tss_struct *tss,
{
lazy_hcall3(LHCALL_SET_STACK, __KERNEL_DS | 0x1, thread->sp0,
THREAD_SIZE / PAGE_SIZE);
+ tss->x86_tss.sp0 = thread->sp0;
}
/* Let's just say, I wouldn't do debugging under a Guest. */