| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 23/74] x86: kvm: avoid constant-conversion warning | Date | Mon, 5 Aug 2019 15:02:36 +0200 |
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[ Upstream commit a6a6d3b1f867d34ba5bd61aa7bb056b48ca67cff ]
clang finds a contruct suspicious that converts an unsigned character to a signed integer and back, causing an overflow:
arch/x86/kvm/mmu.c:4605:39: error: implicit conversion from 'int' to 'u8' (aka 'unsigned char') changes value from -205 to 51 [-Werror,-Wconstant-conversion] u8 wf = (pfec & PFERR_WRITE_MASK) ? ~w : 0; ~~ ^~ arch/x86/kvm/mmu.c:4607:38: error: implicit conversion from 'int' to 'u8' (aka 'unsigned char') changes value from -241 to 15 [-Werror,-Wconstant-conversion] u8 uf = (pfec & PFERR_USER_MASK) ? ~u : 0; ~~ ^~ arch/x86/kvm/mmu.c:4609:39: error: implicit conversion from 'int' to 'u8' (aka 'unsigned char') changes value from -171 to 85 [-Werror,-Wconstant-conversion] u8 ff = (pfec & PFERR_FETCH_MASK) ? ~x : 0; ~~ ^~
Add an explicit cast to tell clang that everything works as intended here.
Signed-off-by: Arnd Bergmann <arnd@arndb.de> Link: https://github.com/ClangBuiltLinux/linux/issues/95 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> --- arch/x86/kvm/mmu.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index e0f982e35c96b..cdc0c460950f3 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -4532,11 +4532,11 @@ static void update_permission_bitmask(struct kvm_vcpu *vcpu, */ /* Faults from writes to non-writable pages */ - u8 wf = (pfec & PFERR_WRITE_MASK) ? ~w : 0; + u8 wf = (pfec & PFERR_WRITE_MASK) ? (u8)~w : 0; /* Faults from user mode accesses to supervisor pages */ - u8 uf = (pfec & PFERR_USER_MASK) ? ~u : 0; + u8 uf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0; /* Faults from fetches of non-executable pages*/ - u8 ff = (pfec & PFERR_FETCH_MASK) ? ~x : 0; + u8 ff = (pfec & PFERR_FETCH_MASK) ? (u8)~x : 0; /* Faults from kernel mode fetches of user pages */ u8 smepf = 0; /* Faults from kernel mode accesses of user pages */ -- 2.20.1
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