diff options
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/Kconfig.debug | 8 | ||||
| -rw-r--r-- | arch/arm64/include/asm/mmu_context.h | 15 | ||||
| -rw-r--r-- | arch/arm64/kernel/process.c | 4 |
3 files changed, 26 insertions, 1 deletions
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug index 79871cd78da..51493430f14 100644 --- a/arch/arm64/Kconfig.debug +++ b/arch/arm64/Kconfig.debug @@ -33,4 +33,12 @@ config EARLY_PRINTK is assumed that the early console device has been initialised by the boot loader prior to starting the Linux kernel. +config PID_IN_CONTEXTIDR + bool "Write the current PID to the CONTEXTIDR register" + help + Enabling this option causes the kernel to write the current PID to + 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/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index f68465dee02..e2bc385adb6 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -35,6 +35,21 @@ extern unsigned int cpu_last_asid; void __init_new_context(struct task_struct *tsk, struct mm_struct *mm); void __new_context(struct mm_struct *mm); +#ifdef CONFIG_PID_IN_CONTEXTIDR +static inline void contextidr_thread_switch(struct task_struct *next) +{ + asm( + " msr contextidr_el1, %0\n" + " isb" + : + : "r" (task_pid_nr(next))); +} +#else +static inline void contextidr_thread_switch(struct task_struct *next) +{ +} +#endif + /* * Set TTBR0 to empty_zero_page. No translations will be possible via TTBR0. */ diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index cb0956bc96e..a8fbd7eaa2e 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -45,9 +45,10 @@ #include <asm/compat.h> #include <asm/cacheflush.h> +#include <asm/fpsimd.h> +#include <asm/mmu_context.h> #include <asm/processor.h> #include <asm/stacktrace.h> -#include <asm/fpsimd.h> static void setup_restart(void) { @@ -319,6 +320,7 @@ struct task_struct *__switch_to(struct task_struct *prev, /* the actual thread switch */ last = cpu_switch_to(prev, next); + contextidr_thread_switch(next); return last; } |