Messages in this thread | | | Subject | Re: [PATCH 2/2] KVM: arm/arm64: Print the EC hex value with its exact width | From | Zenghui Yu <> | Date | Wed, 11 Sep 2019 17:19:05 +0800 |
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Hi Marc,
On 2019/9/11 16:31, Marc Zyngier wrote: > On Wed, 11 Sep 2019 03:33:36 +0100, > Zenghui Yu <yuzenghui@huawei.com> wrote: >> >> EC is the bits [31:26] of ESR_ELx on arm64 (HSR on arm). Print the >> hex value with its exact width (8). >> >> Signed-off-by: Zenghui Yu <yuzenghui@huawei.com> >> --- >> virt/kvm/arm/trace.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/virt/kvm/arm/trace.h b/virt/kvm/arm/trace.h >> index 204d210d01c2..022b0a060034 100644 >> --- a/virt/kvm/arm/trace.h >> +++ b/virt/kvm/arm/trace.h >> @@ -42,7 +42,7 @@ TRACE_EVENT(kvm_exit, >> __entry->vcpu_pc = vcpu_pc; >> ), >> >> - TP_printk("%s: HSR_EC: 0x%04x (%s), PC: 0x%08lx", >> + TP_printk("%s: HSR_EC: 0x%02x (%s), PC: 0x%08lx", >> __print_symbolic(__entry->ret, kvm_arm_exception_type), >> __entry->esr_ec, >> __print_symbolic(__entry->esr_ec, kvm_arm_exception_class), > > Although you're right that 8 bits ought to be enough, this is a change > to the output of the tracepoint, which userspace could (does?) parse.
Well-written userspace tools should only parse the low 8 bits (if they do parse). But even if the high bits are parsed, they're always 0. So I don't think this change will have a bad impact on userspace.
> I'm thus reluctant to change anything there, knowing that we don't > lose any information, and just print two extra zeroes.
Anyway this is not a fix, feel free to ignore it if you're worried about that there might be some issues ;)
> Am I missing anything?
No.
Thanks, zenghui
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