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authorPeter Maydell <peter.maydell@linaro.org>2017-10-06 16:46:49 +0100
committerPeter Maydell <peter.maydell@linaro.org>2017-10-06 16:46:49 +0100
commit35337cc391245f251bfb9134f181c33e6375d6c1 (patch)
tree6380c59cf3108f9cec2bcfb2108819623814c3f0 /ui/sdl_zoom.c
parent9901c576f6c02d43206e5faaf6e362ab7ea83246 (diff)
target/arm: Implement security attribute lookups for memory accesses
Implement the security attribute lookups for memory accesses in the get_phys_addr() functions, causing these to generate various kinds of SecureFault for bad accesses. The major subtlety in this code relates to handling of the case when the security attributes the SAU assigns to the address don't match the current security state of the CPU. In the ARM ARM pseudocode for validating instruction accesses, the security attributes of the address determine whether the Secure or NonSecure MPU state is used. At face value, handling this would require us to encode the relevant bits of state into mmu_idx for both S and NS at once, which would result in our needing 16 mmu indexes. Fortunately we don't actually need to do this because a mismatch between address attributes and CPU state means either: * some kind of fault (usually a SecureFault, but in theory perhaps a UserFault for unaligned access to Device memory) * execution of the SG instruction in NS state from a Secure & NonSecure code region The purpose of SG is simply to flip the CPU into Secure state, so we can handle it by emulating execution of that instruction directly in arm_v7m_cpu_do_interrupt(), which means we can treat all the mismatch cases as "throw an exception" and we don't need to encode the state of the other MPU bank into our mmu_idx values. This commit doesn't include the actual emulation of SG; it also doesn't include implementation of the IDAU, which is a per-board way to specify hard-coded memory attributes for addresses, which override the CPU-internal SAU if they specify a more secure setting than the SAU is programmed to. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 1506092407-26985-15-git-send-email-peter.maydell@linaro.org
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