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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
This commit is contained in:
jah 2020-09-12 07:04:00 +00:00 committed by Sebastian Huber
parent 47efca5ac3
commit 303c61925d
1 changed files with 2 additions and 0 deletions
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2
newlib/libc/include/sys/cdefs.h
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@ -716,8 +716,10 @@
*/ */
#if __has_attribute(no_sanitize) && defined(__clang__) #if __has_attribute(no_sanitize) && defined(__clang__)
#define __nosanitizeaddress __attribute__((no_sanitize("address"))) #define __nosanitizeaddress __attribute__((no_sanitize("address")))
#define __nosanitizethread __attribute__((no_sanitize("thread")))
#else #else
#define __nosanitizeaddress #define __nosanitizeaddress
#define __nosanitizethread
#endif #endif
/* Guard variables and structure members by lock. */ /* Guard variables and structure members by lock. */