On 4/3/21 11:40 PM, Madhavan T. Venkataraman wrote: > > > On 4/3/21 10:46 PM, Madhavan T. Venkataraman wrote: >>> I'm somewhat arm-ignorant, so take the following comments with a grain >>> of salt. >>> >>> >>> I don't think changing these to 'bl' is necessary, unless you wanted >>> __primary_switched() and __secondary_switched() to show up in the >>> stacktrace for some reason? If so, that seems like a separate patch. >>> >> The problem is with __secondary_switched. If you trace the code back to where >> a secondary CPU is started, I don't see any calls anywhere. There are only >> branches if I am not mistaken. So, the return address register never gets >> set up with a proper address. The stack trace shows some hexadecimal value >> instead of a symbol name. >> > > Actually, I take that back. There are calls in that code path. But I did only > see some hexadecimal value instead of a proper address in the stack trace. > Sorry about that confusion. > Again, I apologize. I had this confused with something else in my notes. So, the stack trace looks like this without my changes to convert the branch to secondary_start_kernel() to a call: ... [ 0.022492] secondary_start_kernel+0x188/0x1e0 [ 0.022503] 0xf8689e1cc It looks like the code calls __enable_mmu before reaching the place where it branches to secondary_start_kernel(). bl __enable_mmu The return address register should be set to the next instruction address. I am guessing that the return address is 0xf8689e1cc because of the idmap stuff. Madhavan
