Update Linux to v5.10.109
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz
Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/arch/x86/kernel/cpu/rdrand.c b/arch/x86/kernel/cpu/rdrand.c
index 5c900f9..c4be620 100644
--- a/arch/x86/kernel/cpu/rdrand.c
+++ b/arch/x86/kernel/cpu/rdrand.c
@@ -29,7 +29,8 @@
#ifdef CONFIG_ARCH_RANDOM
void x86_init_rdrand(struct cpuinfo_x86 *c)
{
- unsigned long tmp;
+ unsigned int changed = 0;
+ unsigned long tmp, prev;
int i;
if (!cpu_has(c, X86_FEATURE_RDRAND))
@@ -42,5 +43,24 @@
return;
}
}
+
+ /*
+ * Stupid sanity-check whether RDRAND does *actually* generate
+ * some at least random-looking data.
+ */
+ prev = tmp;
+ for (i = 0; i < SANITY_CHECK_LOOPS; i++) {
+ if (rdrand_long(&tmp)) {
+ if (prev != tmp)
+ changed++;
+
+ prev = tmp;
+ }
+ }
+
+ if (WARN_ON_ONCE(!changed))
+ pr_emerg(
+"RDRAND gives funky smelling output, might consider not using it by booting with \"nordrand\"");
+
}
#endif