From: James Cowgill <James.Cowgill@imgtec.com> To: "James Hogan" <james.hogan@imgtec.com>, "Paolo Bonzini" <pbonzini@redhat.com>, "Radim Krčmář" <rkrcmar@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org>, <linux-mips@linux-mips.org>, <kvm@vger.kernel.org>, James Cowgill <James.Cowgill@imgtec.com> Subject: [PATCH v2] KVM: MIPS: Fix maybe-uninitialized build failure Date: Tue, 20 Jun 2017 10:57:51 +0100 [thread overview] Message-ID: <20170620095751.5443-1-James.Cowgill@imgtec.com> (raw) This commit fixes a "maybe-uninitialized" build failure in arch/mips/kvm/tlb.c when KVM, DYNAMIC_DEBUG and JUMP_LABEL are all enabled. The failure is: In file included from ./include/linux/printk.h:329:0, from ./include/linux/kernel.h:13, from ./include/asm-generic/bug.h:15, from ./arch/mips/include/asm/bug.h:41, from ./include/linux/bug.h:4, from ./include/linux/thread_info.h:11, from ./include/asm-generic/current.h:4, from ./arch/mips/include/generated/asm/current.h:1, from ./include/linux/sched.h:11, from arch/mips/kvm/tlb.c:13: arch/mips/kvm/tlb.c: In function ‘kvm_mips_host_tlb_inv’: ./include/linux/dynamic_debug.h:126:3: error: ‘idx_kernel’ may be used uninitialized in this function [-Werror=maybe-uninitialized] __dynamic_pr_debug(&descriptor, pr_fmt(fmt), \ ^~~~~~~~~~~~~~~~~~ arch/mips/kvm/tlb.c:169:16: note: ‘idx_kernel’ was declared here int idx_user, idx_kernel; ^~~~~~~~~~ There is a similar error relating to "idx_user". Both errors were observed with GCC 6. As far as I can tell, it is impossible for either idx_user or idx_kernel to be uninitialized when they are later read in the calls to kvm_debug, but to satisfy the compiler, add zero initializers to both variables. Signed-off-by: James Cowgill <James.Cowgill@imgtec.com> Fixes: 57e3869cfaae ("KVM: MIPS/TLB: Generalise host TLB invalidate to kernel ASID") Cc: <stable@vger.kernel.org> # 4.11+ --- arch/mips/kvm/tlb.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/mips/kvm/tlb.c b/arch/mips/kvm/tlb.c index 7c6336dd2638..7cd92166a0b9 100644 --- a/arch/mips/kvm/tlb.c +++ b/arch/mips/kvm/tlb.c @@ -166,7 +166,11 @@ static int _kvm_mips_host_tlb_inv(unsigned long entryhi) int kvm_mips_host_tlb_inv(struct kvm_vcpu *vcpu, unsigned long va, bool user, bool kernel) { - int idx_user, idx_kernel; + /* + * Initialize idx_user and idx_kernel to workaround bogus + * maybe-initialized warning when using GCC 6. + */ + int idx_user = 0, idx_kernel = 0; unsigned long flags, old_entryhi; local_irq_save(flags); -- 2.11.0
WARNING: multiple messages have this Message-ID (diff)
From: James Cowgill <James.Cowgill@imgtec.com> To: "James Hogan" <james.hogan@imgtec.com>, "Paolo Bonzini" <pbonzini@redhat.com>, "Radim Krčmář" <rkrcmar@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org, kvm@vger.kernel.org, James Cowgill <James.Cowgill@imgtec.com> Subject: [PATCH v2] KVM: MIPS: Fix maybe-uninitialized build failure Date: Tue, 20 Jun 2017 10:57:51 +0100 [thread overview] Message-ID: <20170620095751.5443-1-James.Cowgill@imgtec.com> (raw) Message-ID: <20170620095751.4sc9x8dYuda5wDvGZBRRRaw-lAEuG5sezTOh2vgtvIA@z> (raw) This commit fixes a "maybe-uninitialized" build failure in arch/mips/kvm/tlb.c when KVM, DYNAMIC_DEBUG and JUMP_LABEL are all enabled. The failure is: In file included from ./include/linux/printk.h:329:0, from ./include/linux/kernel.h:13, from ./include/asm-generic/bug.h:15, from ./arch/mips/include/asm/bug.h:41, from ./include/linux/bug.h:4, from ./include/linux/thread_info.h:11, from ./include/asm-generic/current.h:4, from ./arch/mips/include/generated/asm/current.h:1, from ./include/linux/sched.h:11, from arch/mips/kvm/tlb.c:13: arch/mips/kvm/tlb.c: In function ‘kvm_mips_host_tlb_inv’: ./include/linux/dynamic_debug.h:126:3: error: ‘idx_kernel’ may be used uninitialized in this function [-Werror=maybe-uninitialized] __dynamic_pr_debug(&descriptor, pr_fmt(fmt), \ ^~~~~~~~~~~~~~~~~~ arch/mips/kvm/tlb.c:169:16: note: ‘idx_kernel’ was declared here int idx_user, idx_kernel; ^~~~~~~~~~ There is a similar error relating to "idx_user". Both errors were observed with GCC 6. As far as I can tell, it is impossible for either idx_user or idx_kernel to be uninitialized when they are later read in the calls to kvm_debug, but to satisfy the compiler, add zero initializers to both variables. Signed-off-by: James Cowgill <James.Cowgill@imgtec.com> Fixes: 57e3869cfaae ("KVM: MIPS/TLB: Generalise host TLB invalidate to kernel ASID") Cc: <stable@vger.kernel.org> # 4.11+ --- arch/mips/kvm/tlb.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/mips/kvm/tlb.c b/arch/mips/kvm/tlb.c index 7c6336dd2638..7cd92166a0b9 100644 --- a/arch/mips/kvm/tlb.c +++ b/arch/mips/kvm/tlb.c @@ -166,7 +166,11 @@ static int _kvm_mips_host_tlb_inv(unsigned long entryhi) int kvm_mips_host_tlb_inv(struct kvm_vcpu *vcpu, unsigned long va, bool user, bool kernel) { - int idx_user, idx_kernel; + /* + * Initialize idx_user and idx_kernel to workaround bogus + * maybe-initialized warning when using GCC 6. + */ + int idx_user = 0, idx_kernel = 0; unsigned long flags, old_entryhi; local_irq_save(flags); -- 2.11.0
next reply other threads:[~2017-06-20 9:58 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-06-20 9:57 James Cowgill [this message] 2017-06-20 9:57 ` [PATCH v2] KVM: MIPS: Fix maybe-uninitialized build failure James Cowgill 2017-06-20 14:54 ` James Hogan 2017-06-20 15:07 ` Radim Krčmář
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