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authorJames Hogan <james.hogan@imgtec.com>2016-04-27 23:21:06 +0100
committerLeon Alrae <leon.alrae@imgtec.com>2016-04-28 10:03:24 +0100
commitd96391c1ffeb30a0afa695c86579517c69d9a889 (patch)
tree1999d95b3a6cdb52249bdf35b5982040f4a01fee /target-mips/cpu.h
parentf419a626c76bcb26697883af702862e8623056f9 (diff)
downloadqemu-arm-d96391c1ffeb30a0afa695c86579517c69d9a889.tar.gz
target-mips: Fix RDHWR exception host PC
Commit b00c72180c36 ("target-mips: add PC, XNP reg numbers to RDHWR") changed the rdhwr helpers to use check_hwrena() to check the register being accessed is enabled in CP0_HWREna when used from user mode. If that check fails an EXCP_RI exception is raised at the host PC calculated with GETPC(). However check_hwrena() may not be fully inlined as the do_raise_exception() part of it is common regardless of the arguments. This causes GETPC() to calculate the address in the call in the helper instead of the generated code calling the helper. No TB will be found and the EPC reported with the resulting guest RI exception points to the beginning of the TB instead of the RDHWR instruction. We can't reliably force check_hwrena() to be inlined, and converting it to a macro would be ugly, so instead pass the host PC in as an argument, with each rdhwr helper passing GETPC(). This should avoid any dependence on compiler behaviour, and in practice seems to ensure the full inlining of check_hwrena() on x86_64. This issue causes failures when running a MIPS KVM (trap & emulate) guest in a MIPS QEMU TCG guest, as the inner guest kernel will do a RDHWR of counter, which is disabled in the outer guest's CP0_HWREna by KVM so it can emulate the inner guest's counter. The emulation fails and the RI exception is passed to the inner guest. Fixes: b00c72180c36 ("target-mips: add PC, XNP reg numbers to RDHWR") Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Leon Alrae <leon.alrae@imgtec.com> Cc: Yongbok Kim <yongbok.kim@imgtec.com> Cc: Aurelien Jarno <aurelien@aurel32.net> Reviewed-by: Aurelien Jarno <aurelien@aurel32.net> Reviewed-by: Leon Alrae <leon.alrae@imgtec.com> Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>
Diffstat (limited to 'target-mips/cpu.h')
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