ST.as only takes S9 (255) for offset. This was going out of range when
accessing a task_struct field with 4k NR_CPUS (due to 128b of coumaks
itself in there).
Workaround by using an intermediate register to do the address scaling.
There is some duplication of fix for ctx_sw.c and ctx_sw_asm.S however
given that C version will go away soon I'm not bothering to factor out
the common code.
Reported-by: Noam Camus <noamc@ezchip.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This is trickier than prev two:
* context switching code saves kernel mode callee regs in the format of
struct callee_regs thus needs adjustment. This also reduces the height
of topmost kernel stack frame by 1 word.
* Since kernel stack unwinder is sensitive to height of topmost kernel
stack frame, that needs a word of adjustment too.
ptrace needs a bit of updating since pt_regs now diverges from
user_regs_struct.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC common code to enable a SMP system + ISS provided SMP extensions.
ARC700 natively lacks SMP support, hence some of the core features are
are only enabled if SoCs have the necessary h/w pixie-dust. This
includes:
-Inter Processor Interrupts (IPI)
-Cache coherency
-load-locked/store-conditional
...
The low level exception handling would be completely broken in SMP
because we don't have hardware assisted stack switching. Thus a fair bit
of this code is repurposing the MMU_SCRATCH reg for event handler
prologues to keep them re-entrant.
Many thanks to Rajeshwar Ranga for his initial "major" contributions to
SMP Port (back in 2008), and to Noam Camus and Gilad Ben-Yossef for help
with resurrecting that in 3.2 kernel (2012).
Note that this platform code is again singleton design pattern - so
multiple SMP platforms won't build at the moment - this deficiency is
addressed in subsequent patches within this series.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rajeshwar Ranga <rajeshwar.ranga@gmail.com>
Cc: Noam Camus <noamc@ezchip.com>
Cc: Gilad Ben-Yossef <gilad@benyossef.com>
Vineet Gupta