Re: regression from c/s 22071:c5aed2e049bc (ept: Put locks around ept_get_entry) ?

[Olaf Hering <olaf@aepfle.de>]

On Thu, Dec 16, Keir Fraser wrote:

> Excellent. I will lay groundwork and fix pte_{read,write}_atomic directly in
> -unstable and -4.0-testing. I will then post a proposed fix for EPT to the
> list. I don't know that code so well and I may not otherwise catch all
> places that require use of the new accessor macros.

Keir,

this failure may be related to the changes that went just into
xen-unstable, fails in openSuSE 11.2 and 11.3 on 32bit:

make[2]: Entering directory `/usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/arch/x86'
gcc -fomit-frame-pointer -fmessage-length=0 -O2 -Wall  -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables  -fasynchronous-unwind-tables -O1 -fno-omit-frame-pointer  -fno-optimize-sibling-calls -m32 -march=i686 -g -fno-strict-aliasing  -std=gnu99 -Wall -Wstrict-prototypes -Wno-unused-value  -Wdeclaration-after-statement  -nostdinc -fno-builtin -fno-common  -Wredundant-decls -iwithprefix include -Werror -Wno-pointer-arith -pipe  -I/usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/include   -I/usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/include/asm-x86/mach-generic   -I/usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/include/asm-x86/mach-default  -msoft-float -fno-stack-protector -fno-exceptions -g -D__XEN__  -DVERBOSE -DCRASH_DEBUG -fno-omit-frame-pointer -DCONFIG_FRAME_POINTER  -DMAX_PHYS_CPUS=32 -MMD -MF .xen.d -O1 -fno-omit-frame-pointer  -fno-optimize-sibling-calls -m32 -march=i686 -g -fno-strict-aliasing  -std=gnu99 -Wall -Wstrict-prototypes -Wno-unused-value  -Wdeclaration-after-statement  -nostdinc -fno-builtin -fno-common  -Wredundant-decls -iwithprefix include -Werror -Wno-pointer-arith -pipe  -I/usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/include   -I/usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/include/asm-x86/mach-generic   -I/usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/include/asm-x86/mach-default  -msoft-float -fno-stack-protector -fno-exceptions -g -D__XEN__  -DVERBOSE -DCRASH_DEBUG -fno-omit-frame-pointer -DCONFIG_FRAME_POINTER  -DMAX_PHYS_CPUS=32 -MMD -MF .asm-offsets.s.d -S -o asm-offsets.s  x86_32/asm-offsets.c
cc1: warnings being treated as errors
In file included from /usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/include/asm/spinlock.h:6,
                 from /usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/include/xen/spinlock.h:6,
                 from /usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/include/xen/sched.h:7,
                 from x86_32/asm-offsets.c:9:
/usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/include/asm/atomic.h: In function 'atomic_write64':
/usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/include/asm/atomic.h:39: error: operation on 'old' may be undefined
make[2]: *** [asm-offsets.s] Error 1
make[2]: Leaving directory `/usr/src/packages/BUILD/xen-unstable.hg-4.1.22571/xen/arch/x86'

 36 static inline void atomic_write64(volatile uint64_t *addr, uint64_t val)
 37 {
 38     uint64_t old = *addr, new, *__addr = (uint64_t *)addr;
 39     while ( (old = __cmpxchg8b(__addr, old, val)) != old )
 40         old = new;
 41 }