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powerpc: Add Initiate Coprocessor Store Word (icswx) support

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Icswx is a PowerPC instruction to send data to a co-processor. On Book-S
processors the LPAR_ID and process ID (PID) of the owning process are
registered in the window context of the co-processor at initialization
time. When the icswx instruction is executed the L2 generates a cop-reg
transaction on PowerBus. The transaction has no address and the
processor does not perform an MMU access to authenticate the transaction.
The co-processor compares the LPAR_ID and the PID included in the
transaction and the LPAR_ID and PID held in the window context to
determine if the process is authorized to generate the transaction.

The OS needs to assign a 16-bit PID for the process. This cop-PID needs
to be updated during context switch. The cop-PID needs to be destroyed
when the context is destroyed.

Signed-off-by: Sonny Rao <sonnyrao@linux.vnet.ibm.com>
Signed-off-by: Tseng-Hui (Frank) Lin <thlin@linux.vnet.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Tseng-Hui (Frank) Lin
2011-05-02 20:43:04 +00:00
committed by Benjamin Herrenschmidt
parent a32e252f7c
commit 851d2e2fe8
6 changed files with 249 additions and 1 deletions
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10
arch/powerpc/include/asm/mmu_context.h
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@@ -32,6 +32,10 @@ extern void __destroy_context(unsigned long context_id);
extern void mmu_context_init(void);
#endif
extern void switch_cop(struct mm_struct *next);
extern int use_cop(unsigned long acop, struct mm_struct *mm);
extern void drop_cop(unsigned long acop, struct mm_struct *mm);
/*
* switch_mm is the entry point called from the architecture independent
* code in kernel/sched.c
@@ -55,6 +59,12 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
if (prev == next)
return;
#ifdef CONFIG_PPC_ICSWX
/* Switch coprocessor context only if prev or next uses a coprocessor */
if (prev->context.acop || next->context.acop)
switch_cop(next);
#endif /* CONFIG_PPC_ICSWX */
/* We must stop all altivec streams before changing the HW
* context
*/