arm/arm64: KVM: Map the BSS at HYP

When used with a compiler that doesn't implement "asm goto" (such as the AArch64 port of GCC 4.8), jump labels generate a memory access to find out about the value of the key (instead of just patching the code). The key itself is likely to be stored in the BSS. This is perfectly fine, except that we don't map the BSS at HYP, leading to an exploding kernel at the first access. The obvious fix is simply to map the BSS there (which should have been done a long while ago, but hey...). Reported-by: Eric Auger <[email protected]> Tested-by: Eric Auger <[email protected]> Signed-off-by: Marc Zyngier <[email protected]>
ambv · Oct 21, 2016 · c8ea039 · c8ea039
1 parent 60e21a0
commit c8ea039
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
@@ -1312,6 +1312,13 @@ static int init_hyp_mode(void)
 		goto out_err;
 	}
 
+	err = create_hyp_mappings(kvm_ksym_ref(__bss_start),
+				  kvm_ksym_ref(__bss_stop), PAGE_HYP_RO);
+	if (err) {
+		kvm_err("Cannot map bss section\n");
+		goto out_err;
+	}
+
 	/*
 	 * Map the Hyp stack pages
 	 */