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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/Kconfig.debug
parent3a0310eb369aae985d6409d8ff1340146578e5c1 (diff)
downloadlinux-linaro-stable-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/Kconfig.debug')
-rw-r--r--arch/arm64/Kconfig.debug8
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
index 79871cd78da8..51493430f142 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.
+
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