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ARM: kprobes: Add it_advance() 

This advances the ITSTATE bits in CPSR to their values for the next
instruction.

Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
This commit is contained in:
Jon Medhurst 2011-06-16 14:53:56 +01:00 committed by Tixy
parent eaf4f33fec
commit 6aaa8b5570
1 changed files with 25 additions and 0 deletions
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25
arch/arm/kernel/kprobes.h
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@ -68,6 +68,31 @@ void __init find_str_pc_offset(void);
#endif
/*
* Update ITSTATE after normal execution of an IT block instruction.
*
* The 8 IT state bits are split into two parts in CPSR:
* ITSTATE<1:0> are in CPSR<26:25>
* ITSTATE<7:2> are in CPSR<15:10>
*/
static inline unsigned long it_advance(unsigned long cpsr)
{
if ((cpsr & 0x06000400) == 0) {
/* ITSTATE<2:0> == 0 means end of IT block, so clear IT state */
cpsr &= ~PSR_IT_MASK;
} else {
/* We need to shift left ITSTATE<4:0> */
const unsigned long mask = 0x06001c00; /* Mask ITSTATE<4:0> */
unsigned long it = cpsr & mask;
it <<= 1;
it |= it >> (27 - 10); /* Carry ITSTATE<2> to correct place */
it &= mask;
cpsr &= ~mask;
cpsr |= it;
}
return cpsr;
}
/*
* Test if load/store instructions writeback the address register.
* if P (bit 24) == 0 or W (bit 21) == 1