| Message ID | 20170620095751.5443-1-James.Cowgill@imgtec.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Jun 20, 2017 at 10:57:51AM +0100, James Cowgill wrote: > 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+ Acked-by: James Hogan <james.hogan@imgtec.com> Paolo / Radim: is it okay for one of you to pick this one up for 4.12? Thanks James > --- > 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 >
2017-06-20 15:54+0100, James Hogan: > Acked-by: James Hogan <james.hogan@imgtec.com> > > Paolo / Radim: is it okay for one of you to pick this one up for 4.12? It's in, thanks!
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);
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(-)