Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751465AbdLAUXt (ORCPT ); Fri, 1 Dec 2017 15:23:49 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:35071 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751031AbdLAUXs (ORCPT ); Fri, 1 Dec 2017 15:23:48 -0500 From: Boris Ostrovsky To: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, jgross@suse.com, luto@kernel.org, Boris Ostrovsky Subject: [PATCH v3] x86/entry/64/paravirt: Use paravirt-safe macro to access eflags Date: Fri, 1 Dec 2017 15:23:25 -0500 Message-Id: <1512159805-6314-1-git-send-email-boris.ostrovsky@oracle.com> X-Mailer: git-send-email 1.7.1 X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2930 Lines: 92 Commit 1d3e53e8624a ("x86/entry/64: Refactor IRQ stacks and make them NMI-safe") added DEBUG_ENTRY_ASSERT_IRQS_OFF macro that acceses eflags using 'pushfq' instruction when testing for IF bit. On PV Xen guests looking at IF flag directly will always see it set, resulting in 'ud2'. Introduce SAVE_FLAGS() macro that will use appropriate save_fl pv op when running paravirt. Signed-off-by: Boris Ostrovsky --- V3: * Use CLBR_RAX to preserve all registers except %rax arch/x86/entry/entry_64.S | 7 ++++--- arch/x86/include/asm/irqflags.h | 3 +++ arch/x86/include/asm/paravirt.h | 9 +++++++++ arch/x86/kernel/asm-offsets_64.c | 3 +++ 4 files changed, 19 insertions(+), 3 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index f81d50d..18474bb 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -466,12 +466,13 @@ END(irq_entries_start) .macro DEBUG_ENTRY_ASSERT_IRQS_OFF #ifdef CONFIG_DEBUG_ENTRY - pushfq - testl $X86_EFLAGS_IF, (%rsp) + pushq %rax + SAVE_FLAGS(CLBR_RAX) + testl $X86_EFLAGS_IF, %eax jz .Lokay_\@ ud2 .Lokay_\@: - addq $8, %rsp + popq %rax #endif .endm diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h index c8ef23f..89f0895 100644 --- a/arch/x86/include/asm/irqflags.h +++ b/arch/x86/include/asm/irqflags.h @@ -142,6 +142,9 @@ static inline notrace unsigned long arch_local_irq_save(void) swapgs; \ sysretl +#ifdef CONFIG_DEBUG_ENTRY +#define SAVE_FLAGS(x) pushfq; popq %rax +#endif #else #define INTERRUPT_RETURN iret #define ENABLE_INTERRUPTS_SYSEXIT sti; sysexit diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index 283efca..892df37 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -927,6 +927,15 @@ static inline notrace unsigned long arch_local_irq_save(void) PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_usergs_sysret64), \ CLBR_NONE, \ jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_usergs_sysret64)) + +#ifdef CONFIG_DEBUG_ENTRY +#define SAVE_FLAGS(clobbers) \ + PARA_SITE(PARA_PATCH(pv_irq_ops, PV_IRQ_save_fl), clobbers, \ + PV_SAVE_REGS(clobbers | CLBR_CALLEE_SAVE); \ + call PARA_INDIRECT(pv_irq_ops+PV_IRQ_save_fl); \ + PV_RESTORE_REGS(clobbers | CLBR_CALLEE_SAVE);) +#endif + #endif /* CONFIG_X86_32 */ #endif /* __ASSEMBLY__ */ diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c index 630212f..e3a5175 100644 --- a/arch/x86/kernel/asm-offsets_64.c +++ b/arch/x86/kernel/asm-offsets_64.c @@ -23,6 +23,9 @@ int main(void) #ifdef CONFIG_PARAVIRT OFFSET(PV_CPU_usergs_sysret64, pv_cpu_ops, usergs_sysret64); OFFSET(PV_CPU_swapgs, pv_cpu_ops, swapgs); +#ifdef CONFIG_DEBUG_ENTRY + OFFSET(PV_IRQ_save_fl, pv_irq_ops, save_fl); +#endif BLANK(); #endif -- 1.7.1