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authorWill Deacon <will.deacon@arm.com>2013-01-17 12:31:45 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2013-02-11 18:24:18 +0000
commitec45d1cfd3cb65121fc52f39efc17d832f4f7b91 (patch)
treef588db6111ee97aeddd69e05646cd49c31b353a0 /arch/arm64/include
parent3a0310eb369aae985d6409d8ff1340146578e5c1 (diff)
downloadlinaro-lsk-ec45d1cfd3cb65121fc52f39efc17d832f4f7b91.tar.gz
arm64: mm: update CONTEXTIDR register to contain PID of current process
This patch is a port of 575320d62 ("ARM: 7445/1: mm: update CONTEXTIDR register to contain PID of current process") from ARM that introduces a new Kconfig option which, when enabled, causes the kernel to write the PID of the current task into the CONTEXTIDR register on context switch. This is useful when analysing hardware trace, since writes to this register can be configured to emit an event into the trace stream. Signed-off-by: Will Deacon <will.deacon@arm.com> [catalin.marinas@arm.com: contextidr_thread_switch() moved to mmu_context.h] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/include')
-rw-r--r--arch/arm64/include/asm/mmu_context.h15
1 files changed, 15 insertions, 0 deletions
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.
*/