[PATCH 4/4] [RFC] Use generic ARM instruction set condition code checks for kprobes.

[Leif Lindholm]

This patch changes the kprobes implementation to use the generic ARM
instruction set condition code checks, rather than a dedicated
implementation.

Note, this is a direct interface change, and the resulting code is not
the prettiest, but this is an RFC only.

This code builds and links, but current 3.2-rc2 does not boot on my
Versatile Express board with CONFIG_ARM_KPROBES_TEST enabled either
with or without this patch.

Cc: Tixy <tixy at yxit.co.uk>
Signed-off-by: Leif Lindholm <leif.lindholm at arm.com>
---
 arch/arm/kernel/kprobes-test.c |   71 +++-------------------------------------
 1 files changed, 5 insertions(+), 66 deletions(-)

diff --git a/arch/arm/kernel/kprobes-test.c b/arch/arm/kernel/kprobes-test.c
index e17cdd6..6f5328a 100644
--- a/arch/arm/kernel/kprobes-test.c
+++ b/arch/arm/kernel/kprobes-test.c
@@ -202,6 +202,8 @@
 #include <linux/slab.h>
 #include <linux/kprobes.h>
 
+#include <asm/opcodes.h>
+
 #include "kprobes.h"
 #include "kprobes-test.h"
 
@@ -1048,69 +1050,6 @@ static int test_instance;
  */
 #define PSR_IGNORE_BITS (PSR_A_BIT | PSR_F_BIT)
 
-static unsigned long test_check_cc(int cc, unsigned long cpsr)
-{
-	unsigned long temp;
-
-	switch (cc) {
-	case 0x0: /* eq */
-		return cpsr & PSR_Z_BIT;
-
-	case 0x1: /* ne */
-		return (~cpsr) & PSR_Z_BIT;
-
-	case 0x2: /* cs */
-		return cpsr & PSR_C_BIT;
-
-	case 0x3: /* cc */
-		return (~cpsr) & PSR_C_BIT;
-
-	case 0x4: /* mi */
-		return cpsr & PSR_N_BIT;
-
-	case 0x5: /* pl */
-		return (~cpsr) & PSR_N_BIT;
-
-	case 0x6: /* vs */
-		return cpsr & PSR_V_BIT;
-
-	case 0x7: /* vc */
-		return (~cpsr) & PSR_V_BIT;
-
-	case 0x8: /* hi */
-		cpsr &= ~(cpsr >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */
-		return cpsr & PSR_C_BIT;
-
-	case 0x9: /* ls */
-		cpsr &= ~(cpsr >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */
-		return (~cpsr) & PSR_C_BIT;
-
-	case 0xa: /* ge */
-		cpsr ^= (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
-		return (~cpsr) & PSR_N_BIT;
-
-	case 0xb: /* lt */
-		cpsr ^= (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
-		return cpsr & PSR_N_BIT;
-
-	case 0xc: /* gt */
-		temp = cpsr ^ (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
-		temp |= (cpsr << 1);	   /* PSR_N_BIT |= PSR_Z_BIT */
-		return (~temp) & PSR_N_BIT;
-
-	case 0xd: /* le */
-		temp = cpsr ^ (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
-		temp |= (cpsr << 1);	   /* PSR_N_BIT |= PSR_Z_BIT */
-		return temp & PSR_N_BIT;
-
-	case 0xe: /* al */
-	case 0xf: /* unconditional */
-		return true;
-	}
-	BUG();
-	return false;
-}
-
 static int is_last_scenario;
 static int probe_should_run; /* 0 = no, 1 = yes, -1 = unknown */
 static int memory_needs_checking;
@@ -1128,7 +1067,7 @@ static unsigned long test_context_cpsr(int scenario)
 
 	if (!test_case_is_thumb) {
 		/* Testing ARM code */
-		probe_should_run = test_check_cc(current_instruction >> 28, cpsr) != 0;
+		probe_should_run = arm_check_condition(current_instruction, cpsr) != 0;
 		if (scenario == 15)
 			is_last_scenario = true;
 
@@ -1136,7 +1075,7 @@ static unsigned long test_context_cpsr(int scenario)
 		/* Testing Thumb code without setting ITSTATE */
 		if (kprobe_test_cc_position) {
 			int cc = (current_instruction >> kprobe_test_cc_position) & 0xf;
-			probe_should_run = test_check_cc(cc, cpsr) != 0;
+			probe_should_run = arm_check_condition(cc << 28, cpsr) != 0;
 		}
 
 		if (scenario == 15)
@@ -1163,7 +1102,7 @@ static unsigned long test_context_cpsr(int scenario)
 		cpsr |= (mask & 0x8) << 23;	/* ITSTATE<1> */
 		cpsr |= (mask & 0x10) << 21;	/* ITSTATE<0> */
 
-		probe_should_run = test_check_cc((cpsr >> 12) & 0xf, cpsr) != 0;
+		probe_should_run = arm_check_condition(((cpsr >> 12) & 0xf) << 28, cpsr) != 0;
 
 	} else {
 		/* Testing Thumb code with several combinations of ITSTATE */