Messages in this thread | | | Subject | Re: [PATCH entry v2 3/6] x86/entry/xen: Route #DB correctly on Xen PV | From | Jürgen Groß <> | Date | Mon, 6 Jul 2020 10:57:07 +0200 |
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On 06.07.20 10:41, Michal Kubecek wrote: > On Fri, Jul 03, 2020 at 10:02:55AM -0700, Andy Lutomirski wrote: >> On Xen PV, #DB doesn't use IST. We still need to correctly route it >> depending on whether it came from user or kernel mode. >> >> This patch gets rid of DECLARE/DEFINE_IDTENTRY_XEN -- it was too >> hard to follow the logic. Instead, route #DB and NMI through >> DECLARE/DEFINE_IDTENTRY_RAW on Xen, and do the right thing for #DB. >> Also add more warnings to the exc_debug* handlers to make this type >> of failure more obvious. >> >> This fixes various forms of corruption that happen when usermode >> triggers #DB on Xen PV. >> >> Fixes: 4c0dcd8350a0 ("x86/entry: Implement user mode C entry points for #DB and #MCE") >> Signed-off-by: Andy Lutomirski <luto@kernel.org> >> --- >> arch/x86/include/asm/idtentry.h | 24 ++++++------------------ >> arch/x86/kernel/traps.c | 12 ++++++++++++ >> arch/x86/xen/enlighten_pv.c | 28 ++++++++++++++++++++++++---- >> arch/x86/xen/xen-asm_64.S | 5 ++--- >> 4 files changed, 44 insertions(+), 25 deletions(-) >> >> diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h >> index cf51c50eb356..94333ac3092b 100644 >> --- a/arch/x86/include/asm/idtentry.h >> +++ b/arch/x86/include/asm/idtentry.h > [...] >> @@ -570,11 +554,15 @@ DECLARE_IDTENTRY_MCE(X86_TRAP_MC, exc_machine_check); >> >> /* NMI */ >> DECLARE_IDTENTRY_NMI(X86_TRAP_NMI, exc_nmi); >> -DECLARE_IDTENTRY_XEN(X86_TRAP_NMI, nmi); >> +#ifdef CONFIG_XEN_PV >> +DECLARE_IDTENTRY_RAW(X86_TRAP_NMI, xenpv_exc_nmi); >> +#endif >> >> /* #DB */ >> DECLARE_IDTENTRY_DEBUG(X86_TRAP_DB, exc_debug); >> -DECLARE_IDTENTRY_XEN(X86_TRAP_DB, debug); >> +#ifdef CONFIG_XEN_PV >> +DECLARE_IDTENTRY_RAW(X86_TRAP_DB, xenpv_exc_debug); >> +#endif >> >> /* #DF */ >> DECLARE_IDTENTRY_DF(X86_TRAP_DF, exc_double_fault); > > Hello, > > this patch - now in mainline as commit 13cbc0cd4a30 ("x86/entry/32: Fix > #MC and #DB wiring on x86_32") - seems to break i586 builds with > CONFIG_XEN_PV=y as xenpv_exc_nmi and xenpv_exc_debug are only defined > with CONFIG_X86_64: > > [ 1279s] ld: arch/x86/entry/entry_32.o: in function `asm_xenpv_exc_nmi': > [ 1279s] /home/abuild/rpmbuild/BUILD/kernel-pae-5.8.rc4/linux-5.8-rc4/linux-obj/../arch/x86/include/asm/idtentry.h:557: undefined reference to `xenpv_exc_nmi' > [ 1279s] ld: arch/x86/entry/entry_32.o: in function `asm_xenpv_exc_debug': > [ 1279s] /home/abuild/rpmbuild/BUILD/kernel-pae-5.8.rc4/linux-5.8-rc4/linux-obj/../arch/x86/include/asm/idtentry.h:567: undefined reference to `xenpv_exc_debug'
Fix is already queued in tip/tip.git x86/urgent
Juergen
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