Re: [PATCH v4 4/4] arm/arm64: arch_timer: Use archdata to indicate vdso suitability

Instead of comparing the name to a magic string, use archdata to
explicitly communicate whether the arch timer is suitable for
direct vdso access.

Signed-off-by: Scott Wood <redacted>
---
v4: new patch

I'm putting this after the other patches, in the hopes that if there
are issues with this patch, it doesn't hold up the others.

 arch/arm/Kconfig                     |  1 +
 arch/arm/include/asm/clocksource.h   |  8 ++++++++
 arch/arm/kernel/vdso.c               |  2 +-
 arch/arm64/Kconfig                   |  1 +
 arch/arm64/include/asm/clocksource.h |  8 ++++++++
 arch/arm64/kernel/vdso.c             |  2 +-
 drivers/clocksource/arm_arch_timer.c | 11 +++--------
 7 files changed, 23 insertions(+), 10 deletions(-)
 create mode 100644 arch/arm/include/asm/clocksource.h
 create mode 100644 arch/arm64/include/asm/clocksource.h

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 90542db..dcdcd78 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig

@@ -1,6 +1,7 @@
 config ARM
 	bool
 	default y
+	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_ELF_RANDOMIZE

diff --git a/arch/arm/include/asm/clocksource.h b/arch/arm/include/asm/clocksource.h
new file mode 100644
index 0000000..0b350a7
--- /dev/null
+++ b/arch/arm/include/asm/clocksource.h

@@ -0,0 +1,8 @@
+#ifndef _ASM_CLOCKSOURCE_H
+#define _ASM_CLOCKSOURCE_H
+
+struct arch_clocksource_data {
+	bool vdso_direct;	/* Usable for direct VDSO access? */
+};
+
+#endif

diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
index 994e971..a0affd1 100644
--- a/arch/arm/kernel/vdso.c
+++ b/arch/arm/kernel/vdso.c

@@ -270,7 +270,7 @@ static bool tk_is_cntvct(const struct timekeeper *tk)
 	if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
 		return false;
 
-	if (strcmp(tk->tkr_mono.clock->name, "arch_sys_counter") != 0)
+	if (!tk->tkr_mono.clock->archdata.vdso_direct)
 		return false;
 
 	return true;

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 5a0a691..24c4b2c 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig

@@ -3,6 +3,7 @@ config ARM64
 	select ACPI_CCA_REQUIRED if ACPI
 	select ACPI_GENERIC_GSI if ACPI
 	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
+	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select ARCH_HAS_ELF_RANDOMIZE

diff --git a/arch/arm64/include/asm/clocksource.h b/arch/arm64/include/asm/clocksource.h
new file mode 100644
index 0000000..0b350a7
--- /dev/null
+++ b/arch/arm64/include/asm/clocksource.h

@@ -0,0 +1,8 @@
+#ifndef _ASM_CLOCKSOURCE_H
+#define _ASM_CLOCKSOURCE_H
+
+struct arch_clocksource_data {
+	bool vdso_direct;	/* Usable for direct VDSO access? */
+};