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Mark RutlandandGreg Kroah-Hartman
193d669c7a
commitae24f6b06eupstream. The sve_save_state() and sve_load_state() functions take a 32-bit int argument that describes whether to save/restore the FFR. Their assembly implementations consume the entire 64-bit register containing this 32-bit value, and will attempt to save/restore the FFR if any bit of that 64-bit register is non-zero. Per the AAPCS64 parameter passing rules, the callee is responsible for any necessary widening, and the upper 32-bits are permitted to contain arbitrary values. If the upper 32 bits are non-zero, this could result in an unexpected attempt to save/restore the FFR, and consequently could lead to unexpected traps/undefs/faults. In practice compilers are very unlikely to generate code where the upper 32-bits would be non-zero, but they are permitted to do so. Fix this by only consuming the low 32 bits of the register, and update comments accordingly. The hyp code __sve_save_state() and __sve_restore_state() functions don't have the same latent bug as they override the full 64-bit register containing the argument. Fixes:9f58486657("arm64/sve: Make access to FFR optional") Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Fuad Tabba <tabba@google.com> Cc: James Morse <james.morse@arm.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Brown <broonie@kernel.org> Cc: Oliver Upton <oupton@kernel.org> Cc: Vladimir Murzin <vladimir.murzin@arm.com> Cc: Will Deacon <will@kernel.org> Cc: stable@vger.kernel.org Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>