Peter Zijlstra ed63e785cc x86/uaccess: Implement macros for CMPXCHG on user addresses ... [ Upstream commit 989b5db215a2f22f89d730b607b071d964780f10 ] 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> Signed-off-by: Sasha Levin <sashal@kernel.org>		2024-11-18 22:25:35 +01:00
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asm	x86/uaccess: Implement macros for CMPXCHG on user addresses	2024-11-18 22:25:35 +01:00
uapi/asm	Import A536BXXU9EXDC	2024-06-15 16:02:09 -03:00