MIPS: math-emu: Fix jalr emulation when rd == $0
When emulating a jalr instruction with rd == $0, the code in isBranchInstr was incorrectly writing to GPR $0 which should actually always remain zeroed. This would lead to any further instructions emulated which use $0 operating on a bogus value until the task is next context switched, at which point the value of $0 in the task context would be restored to the correct zero by a store in SAVE_SOME. Fix this by not writing to rd if it is $0. Fixes: 102cedc3 ("MIPS: microMIPS: Floating point support.") Signed-off-by: NPaul Burton <paul.burton@imgtec.com> Cc: Maciej W. Rozycki <macro@imgtec.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Cc: stable <stable@vger.kernel.org> # v3.10 Patchwork: https://patchwork.linux-mips.org/patch/13160/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
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