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author | Peter Zijlstra <peterz@infradead.org> | 2022-02-02 03:49:42 +0300 |
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committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-04-13 20:37:47 +0300 |
commit | 989b5db215a2f22f89d730b607b071d964780f10 (patch) | |
tree | a48dcc261dd512fc47863dd9280176aa31885276 /fs | |
parent | 1aa0e8b144b6474c4914439d232d15bfe883636b (diff) | |
download | linux-989b5db215a2f22f89d730b607b071d964780f10.tar.xz |
x86/uaccess: Implement macros for CMPXCHG on user addresses
Add support for CMPXCHG loops on userspace addresses. Provide both an
"unsafe" version for tight loops that do their own uaccess begin/end, as
well as a "safe" version for use cases where the CMPXCHG is not buried in
a loop, e.g. KVM will resume the guest instead of looping when emulation
of a guest atomic accesses fails the CMPXCHG.
Provide 8-byte versions for 32-bit kernels so that KVM can do CMPXCHG on
guest PAE PTEs, which are accessed via userspace addresses.
Guard the asm_volatile_goto() variation with CC_HAS_ASM_GOTO_TIED_OUTPUT,
the "+m" constraint fails on some compilers that otherwise support
CC_HAS_ASM_GOTO_OUTPUT.
Cc: stable@vger.kernel.org
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220202004945.2540433-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'fs')
0 files changed, 0 insertions, 0 deletions