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arm64: mm: update CONTEXTIDR register to contain PID of current process

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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>
This commit is contained in:
Will Deacon
2013-01-17 12:31:45 +00:00
committed by Catalin Marinas
parent 3a0310eb36
commit ec45d1cfd3
3 changed files with 26 additions and 1 deletions
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4
arch/arm64/kernel/process.c
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@@ -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;
}