From 303c61925d9256be02dcbda8f1e5e0d4adf8b3b9 Mon Sep 17 00:00:00 2001 From: jah Date: Sat, 12 Sep 2020 07:04:00 +0000 Subject: [PATCH] amd64: prevent KCSan false positives on LAPIC mapping For configurations without x2APIC support (guests, older hardware), the global LAPIC MMIO mapping will trigger false-positive KCSan reports as it will appear that multiple CPUs are concurrently reading and writing the same address. This isn't actually true, as the underlying physical access will be performed on the local CPU's APIC. Additionally, because LAPIC access can happen during event timer configuration, the resulting KCSan printf can produce a panic due to attempted recursion on event timer resources. Add a __nosanitizethread preprocessor define to prevent the compiler from inserting TSan hooks, and apply it to the x86 LAPIC accessors. PR: 249149 Reported by: gbe Reviewed by: andrew, kib Tested by: gbe Differential Revision: https://reviews.freebsd.org/D26354 --- newlib/libc/include/sys/cdefs.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/newlib/libc/include/sys/cdefs.h b/newlib/libc/include/sys/cdefs.h index 1be994ffd..da7290921 100644 --- a/newlib/libc/include/sys/cdefs.h +++ b/newlib/libc/include/sys/cdefs.h @@ -716,8 +716,10 @@ */ #if __has_attribute(no_sanitize) && defined(__clang__) #define __nosanitizeaddress __attribute__((no_sanitize("address"))) +#define __nosanitizethread __attribute__((no_sanitize("thread"))) #else #define __nosanitizeaddress +#define __nosanitizethread #endif /* Guard variables and structure members by lock. */ -- 2.43.5