From a4c0e91d1d65bc58f928b80ed824e10e165da22c Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 5 Jul 2020 21:33:11 +0200 Subject: [PATCH 1/4] x86/entry/32: Fix XEN_PV build dependency xenpv_exc_nmi() and xenpv_exc_debug() are only defined on 64-bit kernels, but they snuck into the 32-bit build via , causing the link to fail: ld: arch/x86/entry/entry_32.o: in function `asm_xenpv_exc_nmi': (.entry.text+0x817): undefined reference to `xenpv_exc_nmi' ld: arch/x86/entry/entry_32.o: in function `asm_xenpv_exc_debug': (.entry.text+0x827): undefined reference to `xenpv_exc_debug' Only use them on 64-bit kernels. Fixes: f41f0824224e: ("x86/entry/xen: Route #DB correctly on Xen PV") Cc: Andy Lutomirski Cc: Thomas Gleixner Cc: Peter Zijlstra (Intel) Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- arch/x86/include/asm/idtentry.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index eeac6dc2adaa..f3d70830bf2a 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -553,7 +553,7 @@ DECLARE_IDTENTRY_RAW(X86_TRAP_MC, exc_machine_check); /* NMI */ DECLARE_IDTENTRY_NMI(X86_TRAP_NMI, exc_nmi); -#ifdef CONFIG_XEN_PV +#if defined(CONFIG_XEN_PV) && defined(CONFIG_X86_64) DECLARE_IDTENTRY_RAW(X86_TRAP_NMI, xenpv_exc_nmi); #endif @@ -563,7 +563,7 @@ DECLARE_IDTENTRY_DEBUG(X86_TRAP_DB, exc_debug); #else DECLARE_IDTENTRY_RAW(X86_TRAP_DB, exc_debug); #endif -#ifdef CONFIG_XEN_PV +#if defined(CONFIG_XEN_PV) && defined(CONFIG_X86_64) DECLARE_IDTENTRY_RAW(X86_TRAP_DB, xenpv_exc_debug); #endif From bce9b042ec73e8662b8119d4ca47e7c78b20d0bf Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 8 Jul 2020 21:28:05 +0200 Subject: [PATCH 2/4] x86/traps: Disable interrupts in exc_aligment_check() exc_alignment_check() fails to disable interrupts before returning to the entry code. Fixes: ca4c6a9858c2 ("x86/traps: Make interrupt enable/disable symmetric in C code") Reported-by: syzbot+0889df9502bc0f112b31@syzkaller.appspotmail.com Signed-off-by: Thomas Gleixner Acked-by: Andy Lutomirski Link: https://lkml.kernel.org/r/20200708192934.076519438@linutronix.de --- arch/x86/kernel/traps.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 6ed8cc5fbe8f..4f3a509e5547 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -299,6 +299,8 @@ DEFINE_IDTENTRY_ERRORCODE(exc_alignment_check) do_trap(X86_TRAP_AC, SIGBUS, "alignment check", regs, error_code, BUS_ADRALN, NULL); + + local_irq_disable(); } #ifdef CONFIG_VMAP_STACK From 006e1ced516d2bfd9db63a32b5dba3c2abf43b04 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 8 Jul 2020 21:28:06 +0200 Subject: [PATCH 3/4] x86/entry: Mark check_user_regs() noinstr It's called from the non-instrumentable section. Fixes: c9c26150e61d ("x86/entry: Assert that syscalls are on the right stack") Signed-off-by: Thomas Gleixner Acked-by: Andy Lutomirski Link: https://lkml.kernel.org/r/20200708192934.191497962@linutronix.de --- arch/x86/entry/common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index e83b3f14897c..ea7b515e3bc2 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -46,7 +46,7 @@ #include /* Check that the stack and regs on entry from user mode are sane. */ -static void check_user_regs(struct pt_regs *regs) +static noinstr void check_user_regs(struct pt_regs *regs) { if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) { /* From bd87e6f6610aa96fde01ee6653e162213f7ec836 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 8 Jul 2020 21:28:07 +0200 Subject: [PATCH 4/4] x86/entry/common: Make prepare_exit_to_usermode() static No users outside this file anymore. Signed-off-by: Thomas Gleixner Acked-by: Andy Lutomirski Link: https://lkml.kernel.org/r/20200708192934.301116609@linutronix.de --- arch/x86/entry/common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index ea7b515e3bc2..f09288431f28 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -294,7 +294,7 @@ static void __prepare_exit_to_usermode(struct pt_regs *regs) #endif } -__visible noinstr void prepare_exit_to_usermode(struct pt_regs *regs) +static noinstr void prepare_exit_to_usermode(struct pt_regs *regs) { instrumentation_begin(); __prepare_exit_to_usermode(regs);