From c245dcd326fb9f8cca4b396796f0d2e54171b5c9 Mon Sep 17 00:00:00 2001 From: Leif Lindholm Date: Mon, 12 Dec 2011 19:45:24 +0100 Subject: [PATCH] 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 Reviewed-by: Will Deacon Signed-off-by: Russell King --- arch/arm/kernel/swp_emulate.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) 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 #include +#include #include #include @@ -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);