[PATCH 14/51] ARM: kprobes: Add it_advance()
Tixy
tixy at yxit.co.uk
Sat Jul 9 06:57:01 EDT 2011
From: Jon Medhurst <tixy at yxit.co.uk>
This advances the ITSTATE bits in CPSR to their values for the next
instruction.
Signed-off-by: Jon Medhurst <tixy at yxit.co.uk>
---
arch/arm/kernel/kprobes.h | 25 +++++++++++++++++++++++++
1 files changed, 25 insertions(+), 0 deletions(-)
diff --git a/arch/arm/kernel/kprobes.h b/arch/arm/kernel/kprobes.h
index a84b14d..5e2485c 100644
--- a/arch/arm/kernel/kprobes.h
+++ b/arch/arm/kernel/kprobes.h
@@ -69,6 +69,31 @@ void __init find_str_pc_offset(void);
/*
+ * 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
*/
--
1.7.2.5
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