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authorLeif Lindholm <leif.lindholm@arm.com>2011-12-12 19:45:24 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-12-13 08:52:03 +0000
commitc245dcd326fb9f8cca4b396796f0d2e54171b5c9 (patch)
tree4c7d4f696a6912a64d5acd4f01ca42d453722b86 /arch/arm/kernel/swp_emulate.c
parente7f626db83689f55089717a6d771c57afe1adc1a (diff)
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ARM: 7208/1: Add condition code checking to SWP emulation handler.
This patch fixes two separate issues with the SWP emulation handler: 1: Certain processors implementing ARMv7-A can (legally) take an undef exception even when the condition code would have meant that the instruction should not have been executed. 2: Opcodes with all flags set (condition code = 0xf) have been reused in recent, and not-so-recent, versions of the ARM architecture to implement unconditional extensions to the instruction set. The existing code would still have processed any undefs triggered by executing an opcode with such a value. This patch uses the new generic ARM instruction set condition code checks to implement proper handling of these situations. Signed-off-by: Leif Lindholm <leif.lindholm@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/swp_emulate.c')
-rw-r--r--arch/arm/kernel/swp_emulate.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/arm/kernel/swp_emulate.c b/arch/arm/kernel/swp_emulate.c
index 5f452f8fde05..df745188f5de 100644
--- a/arch/arm/kernel/swp_emulate.c
+++ b/arch/arm/kernel/swp_emulate.c
@@ -25,6 +25,7 @@
#include <linux/syscalls.h>
#include <linux/perf_event.h>
+#include <asm/opcodes.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
@@ -185,6 +186,21 @@ static int swp_handler(struct pt_regs *regs, unsigned int instr)
perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, regs->ARM_pc);
+ res = arm_check_condition(instr, regs->ARM_cpsr);
+ switch (res) {
+ case ARM_OPCODE_CONDTEST_PASS:
+ break;
+ case ARM_OPCODE_CONDTEST_FAIL:
+ /* Condition failed - return to next instruction */
+ regs->ARM_pc += 4;
+ return 0;
+ case ARM_OPCODE_CONDTEST_UNCOND:
+ /* If unconditional encoding - not a SWP, undef */
+ return -EFAULT;
+ default:
+ return -EINVAL;
+ }
+
if (current->pid != previous_pid) {
pr_debug("\"%s\" (%ld) uses deprecated SWP{B} instruction\n",
current->comm, (unsigned long)current->pid);
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