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@xxxxxxx> --- arch/arm/kernel/swp_emulate.c | 12 ++++++++++++ 1 files changed, 12 insertions(+), 0 deletions(-) diff --git a/arch/arm/kernel/swp_emulate.c b/arch/arm/kernel/swp_emulate.c index 5f452f8..6a5210e 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 +186,17 @@ 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_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; + } + if (current->pid != previous_pid) { pr_debug("\"%s\" (%ld) uses deprecated SWP{B} instruction\n", current->comm, (unsigned long)current->pid); _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/linux-arm-kernel