diff options
| -rw-r--r-- | arch/arm/Kconfig.debug | 9 | ||||
| -rw-r--r-- | arch/arm/mm/context.c | 35 | ||||
| -rw-r--r-- | arch/arm/mm/proc-v6.S | 6 | ||||
| -rw-r--r-- | arch/arm/mm/proc-v7-2level.S | 5 |
4 files changed, 55 insertions, 0 deletions
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug index 01a134141216..521e15bc6401 100644 --- a/arch/arm/Kconfig.debug +++ b/arch/arm/Kconfig.debug @@ -369,4 +369,13 @@ config ARM_KPROBES_TEST help Perform tests of kprobes API and instruction set simulation. +config PID_IN_CONTEXTIDR + bool "Write the current PID to the CONTEXTIDR register" + depends on CPU_COPY_V6 + help + Enabling this option causes the kernel to write the current PID to + the PROCID field of the CONTEXTIDR register, at the expense of some + additional instructions during context switch. Say Y here only if you + are planning to use hardware trace tools with this kernel. + endmenu diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c index 806cc4f63516..119bc52ab93e 100644 --- a/arch/arm/mm/context.c +++ b/arch/arm/mm/context.c @@ -14,6 +14,7 @@ #include <linux/percpu.h> #include <asm/mmu_context.h> +#include <asm/thread_notify.h> #include <asm/tlbflush.h> static DEFINE_RAW_SPINLOCK(cpu_asid_lock); @@ -48,6 +49,40 @@ void cpu_set_reserved_ttbr0(void) } #endif +#ifdef CONFIG_PID_IN_CONTEXTIDR +static int contextidr_notifier(struct notifier_block *unused, unsigned long cmd, + void *t) +{ + u32 contextidr; + pid_t pid; + struct thread_info *thread = t; + + if (cmd != THREAD_NOTIFY_SWITCH) + return NOTIFY_DONE; + + pid = task_pid_nr(thread->task) << ASID_BITS; + asm volatile( + " mrc p15, 0, %0, c13, c0, 1\n" + " bfi %1, %0, #0, %2\n" + " mcr p15, 0, %1, c13, c0, 1\n" + : "=r" (contextidr), "+r" (pid) + : "I" (ASID_BITS)); + isb(); + + return NOTIFY_OK; +} + +static struct notifier_block contextidr_notifier_block = { + .notifier_call = contextidr_notifier, +}; + +static int __init contextidr_notifier_init(void) +{ + return thread_register_notifier(&contextidr_notifier_block); +} +arch_initcall(contextidr_notifier_init); +#endif + /* * We fork()ed a process, and we need a new context for the child * to run in. diff --git a/arch/arm/mm/proc-v6.S b/arch/arm/mm/proc-v6.S index 5900cd520e84..86b8b480634f 100644 --- a/arch/arm/mm/proc-v6.S +++ b/arch/arm/mm/proc-v6.S @@ -107,6 +107,12 @@ ENTRY(cpu_v6_switch_mm) mcr p15, 0, r2, c7, c5, 6 @ flush BTAC/BTB mcr p15, 0, r2, c7, c10, 4 @ drain write buffer mcr p15, 0, r0, c2, c0, 0 @ set TTB 0 +#ifdef CONFIG_PID_IN_CONTEXTIDR + mrc p15, 0, r2, c13, c0, 1 @ read current context ID + bic r2, r2, #0xff @ extract the PID + and r1, r1, #0xff + orr r1, r1, r2 @ insert into new context ID +#endif mcr p15, 0, r1, c13, c0, 1 @ set context ID #endif mov pc, lr diff --git a/arch/arm/mm/proc-v7-2level.S b/arch/arm/mm/proc-v7-2level.S index 42ac069c8012..fd045e706390 100644 --- a/arch/arm/mm/proc-v7-2level.S +++ b/arch/arm/mm/proc-v7-2level.S @@ -46,6 +46,11 @@ ENTRY(cpu_v7_switch_mm) #ifdef CONFIG_ARM_ERRATA_430973 mcr p15, 0, r2, c7, c5, 6 @ flush BTAC/BTB #endif +#ifdef CONFIG_PID_IN_CONTEXTIDR + mrc p15, 0, r2, c13, c0, 1 @ read current context ID + lsr r2, r2, #8 @ extract the PID + bfi r1, r2, #8, #24 @ insert into new context ID +#endif #ifdef CONFIG_ARM_ERRATA_754322 dsb #endif |