aboutsummaryrefslogtreecommitdiff
path: root/arch/um/include
diff options
context:
space:
mode:
authorGravatar Jason A. Donenfeld <Jason@zx2c4.com> 2022-04-08 18:03:13 +0200
committerGravatar Jason A. Donenfeld <Jason@zx2c4.com> 2022-05-13 23:59:23 +0200
commit3bd4abc07a267e6a8b33d7f8717136e18f921c53 (patch)
tree58f883f0c0bdb6332d4ce7d45bd48a49758c71fd /arch/um/include
parentnios2: use fallback for random_get_entropy() instead of zero (diff)
downloadlinux-3bd4abc07a267e6a8b33d7f8717136e18f921c53.tar.gz
linux-3bd4abc07a267e6a8b33d7f8717136e18f921c53.tar.bz2
linux-3bd4abc07a267e6a8b33d7f8717136e18f921c53.zip
x86/tsc: Use fallback for random_get_entropy() instead of zero
In the event that random_get_entropy() can't access a cycle counter or similar, falling back to returning 0 is suboptimal. Instead, fallback to calling random_get_entropy_fallback(), which isn't extremely high precision or guaranteed to be entropic, but is certainly better than returning zero all the time. If CONFIG_X86_TSC=n, then it's possible for the kernel to run on systems without RDTSC, such as 486 and certain 586, so the fallback code is only required for that case. As well, fix up both the new function and the get_cycles() function from which it was derived to use cpu_feature_enabled() rather than boot_cpu_has(), and use !IS_ENABLED() instead of #ifndef. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: x86@kernel.org
Diffstat (limited to 'arch/um/include')
0 files changed, 0 insertions, 0 deletions