ARM SMC Calling Convention interface

Hi,

This patch set is based on the Generic TEE subsystem v6 patchset
(https://lwn.net/Articles/662495/) sent out a some time ago. By isolating the ARM SMC Calling Convention patches that are useful for other purposes than to support the Generic TEE subsystem some complexity is removed from that patch set.

This patch set adds a common interface to do an SMC or HVC following ARM SMC Calling Convention. The interface is implemented for both the arm and arm64 architectures and updates the PSCI driver to use this interface instead for firmware communication.

Kevins previous Tested-by tag isn't included as the changes in the config variables may affect some of the builds.

v7:
* Use shift macros for all fields supplied to ARM_SMCCC_CALL_VAL()
* Move "select HAVE_ARM_SMCCC if CPU_V7" from "select HAVE_ARM_SMCCC if CPU_V7"
* arm: "config ARM_PSCI" now depends on HAVE_ARM_SMCCC instead of CPU_V7

v6:
* Move HAVE_ARM_SMCCC from init/Kconfig

v5:
* Fixes compile errors for Thumb-2 kernels reported by Kevin Hilman
* drivers: psci: replace psci firmware calls

v4:
* Rebased on v4.4-rc3 to resolve a PSCI conflict
* drivers: psci: replace psci firmware calls

v3:
* Moved the export of arm_smccc_{smc,hvc} to armksyms.c for both arm and arm64
* arm: add implementation for arm-smccc

* arm64: add implementation for arm-smccc
drivers: psci: replace psci firmware calls

v2:
* Added unwinding support in the assembly functions

Thanks,
Jens

Jens Wiklander (4):
arm/arm64: add arm-smccc
arm: add implementation for arm-smccc
arm64: add implementation for arm-smccc
drivers: psci: replace psci firmware calls

 arch/Kconfig                    |   3 ++
 arch/arm/Kconfig                |   3 +-
 arch/arm/kernel/Makefile        |   3 +-
 arch/arm/kernel/armksyms.c      |   6 +++
 arch/arm/kernel/psci-call.S     |  31 ------------
 arch/arm/kernel/smccc-call.S    |  62 ++++++++++++++++++++++++
 arch/arm64/Kconfig              |   1 +
 arch/arm64/kernel/Makefile      |   4 +-
 arch/arm64/kernel/arm64ksyms.c  |   5 ++
 arch/arm64/kernel/asm-offsets.c |   3 ++
 arch/arm64/kernel/psci-call.S   |  28 -----------
 arch/arm64/kernel/smccc-call.S  |  43 +++++++++++++++++
 drivers/firmware/psci.c         |  23 ++++++++-
 include/linux/arm-smccc.h       | 104 ++++++++++++++++++++++++++++++++++++++++
 14 files changed, 254 insertions(+), 65 deletions(-)
 delete mode 100644 arch/arm/kernel/psci-call.S
 create mode 100644 arch/arm/kernel/smccc-call.S
 delete mode 100644 arch/arm64/kernel/psci-call.S
 create mode 100644 arch/arm64/kernel/smccc-call.S
 create mode 100644 include/linux/arm-smccc.h

1.9.1

Adds helpers to do SMC and HVC based on ARM SMC Calling Convention. CONFIG_HAVE_ARM_SMCCC is enabled for architectures that may support the SMC or HVC instruction. It's the responsibility of the caller to know if the SMC instruction is supported by the platform.

This patch doesn't provide an implementation of the declared functions. Later patches will bring in implementations and set CONFIG_HAVE_ARM_SMCCC for ARM and ARM64 respectively.

---
 arch/Kconfig              |   3 ++
 include/linux/arm-smccc.h | 104 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 107 insertions(+)
 create mode 100644 include/linux/arm-smccc.h

index 4e949e5..ce3c0b0 100644
@@ -564,4 +564,7 @@ config OLD_SIGACTION
 config COMPAT_OLD_SIGACTION
 	bool
 
+config HAVE_ARM_SMCCC
+	bool
+
 source "kernel/gcov/Kconfig"

1.9.1

Adds implementation for arm-smccc and enables CONFIG_HAVE_SMCCC for architectures that may support arm-smccc. It's the responsibility of the caller to know if the SMC instruction is supported by the platform.

---
 arch/arm/Kconfig             |  1 +
 arch/arm/kernel/Makefile     |  2 ++
 arch/arm/kernel/armksyms.c   |  6 +++++
 arch/arm/kernel/smccc-call.S | 62 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 71 insertions(+)
 create mode 100644 arch/arm/kernel/smccc-call.S

index 34e1569..36b9490 100644
@@ -37,6 +37,7 @@ config ARM
 	select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32
 	select HAVE_ARCH_SECCOMP_FILTER if (AEABI && !OABI_COMPAT)
 	select HAVE_ARCH_TRACEHOOK
+	select HAVE_ARM_SMCCC if CPU_V7
 	select HAVE_BPF_JIT
 	select HAVE_CC_STACKPROTECTOR
 	select HAVE_CONTEXT_TRACKING

index af9e59b..d2d0042 100644
@@ -92,4 +92,6 @@ obj-y				+= psci-call.o
 obj-$(CONFIG_SMP)		+= psci_smp.o
 endif
 
+obj-$(CONFIG_HAVE_ARM_SMCCC)	+= smccc-call.o
+
 extra-y := $(head-y) vmlinux.lds

index f89811f..7e45f69 100644
@@ -16,6 +16,7 @@
 #include <linux/syscalls.h>
 #include <linux/uaccess.h>
 #include <linux/io.h>
+#include <linux/arm-smccc.h>
 
 #include <asm/checksum.h>
 #include <asm/ftrace.h>

@@ -175,3 +176,8 @@ EXPORT_SYMBOL(__gnu_mcount_nc);
 EXPORT_SYMBOL(__pv_phys_pfn_offset);
 EXPORT_SYMBOL(__pv_offset);
 #endif
+
+#ifdef CONFIG_HAVE_ARM_SMCCC
+EXPORT_SYMBOL(arm_smccc_smc);
+EXPORT_SYMBOL(arm_smccc_hvc);
+#endif

1.9.1

Adds implementation for arm-smccc and enables CONFIG_HAVE_SMCCC.

---
 arch/arm64/Kconfig              |  1 +
 arch/arm64/kernel/Makefile      |  2 +-
 arch/arm64/kernel/arm64ksyms.c  |  5 +++++
 arch/arm64/kernel/asm-offsets.c |  3 +++
 arch/arm64/kernel/smccc-call.S  | 43 +++++++++++++++++++++++++++++++++++++++++
 5 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/kernel/smccc-call.S

index 871f217..96513d0 100644
@@ -92,6 +92,7 @@ config ARM64
 	select SPARSE_IRQ
 	select SYSCTL_EXCEPTION_TRACE
 	select HAVE_CONTEXT_TRACKING
+	select HAVE_ARM_SMCCC
 	help
 	  ARM 64-bit (AArch64) Linux support.
 

index 474691f..0170bea 100644
@@ -17,7 +17,7 @@ arm64-obj-y		:= debug-monitors.o entry.o irq.o fpsimd.o		\
 			   hyp-stub.o psci.o psci-call.o cpu_ops.o insn.o	\
 			   return_address.o cpuinfo.o cpu_errata.o		\
 			   cpufeature.o alternative.o cacheinfo.o		\
-			   smp.o smp_spin_table.o topology.o
+			   smp.o smp_spin_table.o topology.o smccc-call.o
 
 extra-$(CONFIG_EFI)			:= efi-entry.o
 

index 3b6d8cc..678f30b0 100644
@@ -26,6 +26,7 @@
 #include <linux/syscalls.h>
 #include <linux/uaccess.h>
 #include <linux/io.h>
+#include <linux/arm-smccc.h>
 
 #include <asm/checksum.h>
 

@@ -68,3 +69,7 @@ EXPORT_SYMBOL(test_and_change_bit);
 #ifdef CONFIG_FUNCTION_TRACER
 EXPORT_SYMBOL(_mcount);
 #endif
+
+	/* arm-smccc */
+EXPORT_SYMBOL(arm_smccc_smc);
+EXPORT_SYMBOL(arm_smccc_hvc);

index 25de8b2..bb493d4 100644
@@ -28,6 +28,7 @@
 #include <asm/suspend.h>
 #include <asm/vdso_datapage.h>
 #include <linux/kbuild.h>
+#include <linux/arm-smccc.h>
 
 int main(void)
 {

@@ -161,5 +162,7 @@ int main(void)
   DEFINE(SLEEP_SAVE_SP_PHYS,	offsetof(struct sleep_save_sp, save_ptr_stash_phys));
   DEFINE(SLEEP_SAVE_SP_VIRT,	offsetof(struct sleep_save_sp, save_ptr_stash));
 #endif
+  DEFINE(ARM_SMCCC_RES_X0_OFFS,	offsetof(struct arm_smccc_res, a0));
+  DEFINE(ARM_SMCCC_RES_X2_OFFS,	offsetof(struct arm_smccc_res, a2));
   return 0;
 }

1.9.1

Switch to use a generic interface for issuing SMC/HVC based on ARM SMC Calling Convention. Removes now the now unused psci-call.S.

---
 arch/arm/Kconfig              |  2 +-
 arch/arm/kernel/Makefile      |  1 -
 arch/arm/kernel/psci-call.S   | 31 -------------------------------
 arch/arm64/kernel/Makefile    |  2 +-
 arch/arm64/kernel/psci-call.S | 28 ----------------------------
 drivers/firmware/psci.c       | 23 +++++++++++++++++++++--
 6 files changed, 23 insertions(+), 64 deletions(-)
 delete mode 100644 arch/arm/kernel/psci-call.S
 delete mode 100644 arch/arm64/kernel/psci-call.S

index 36b9490..2687c93 100644
@@ -1482,7 +1482,7 @@ config HOTPLUG_CPU
 
 config ARM_PSCI
 	bool "Support for the ARM Power State Coordination Interface (PSCI)"
-	depends on CPU_V7
+	depends on HAVE_ARM_SMCCC
 	select ARM_PSCI_FW
 	help
 	  Say Y here if you want Linux to communicate with system firmware

index d2d0042..80856de 100644
@@ -88,7 +88,6 @@ obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 
 obj-$(CONFIG_ARM_VIRT_EXT)	+= hyp-stub.o
 ifeq ($(CONFIG_ARM_PSCI),y)
-obj-y				+= psci-call.o
 obj-$(CONFIG_SMP)		+= psci_smp.o
 endif
 

deleted file mode 100644
index a78e9e1..0000000
@@ -1,31 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * Copyright (C) 2015 ARM Limited
- *
- * Author: Mark Rutland <[email protected]>
- */
-
-#include <linux/linkage.h>
-
-#include <asm/opcodes-sec.h>
-#include <asm/opcodes-virt.h>
-
-/* int __invoke_psci_fn_hvc(u32 function_id, u32 arg0, u32 arg1, u32 arg2) */
-ENTRY(__invoke_psci_fn_hvc)
-	__HVC(0)
-	bx	lr
-ENDPROC(__invoke_psci_fn_hvc)
-
-/* int __invoke_psci_fn_smc(u32 function_id, u32 arg0, u32 arg1, u32 arg2) */
-ENTRY(__invoke_psci_fn_smc)
-	__SMC(0)
-	bx	lr
-ENDPROC(__invoke_psci_fn_smc)

index 0170bea..27bf1e5 100644
@@ -14,7 +14,7 @@ CFLAGS_REMOVE_return_address.o = -pg
 arm64-obj-y		:= debug-monitors.o entry.o irq.o fpsimd.o		\
 			   entry-fpsimd.o process.o ptrace.o setup.o signal.o	\
 			   sys.o stacktrace.o time.o traps.o io.o vdso.o	\
-			   hyp-stub.o psci.o psci-call.o cpu_ops.o insn.o	\
+			   hyp-stub.o psci.o cpu_ops.o insn.o	\
 			   return_address.o cpuinfo.o cpu_errata.o		\
 			   cpufeature.o alternative.o cacheinfo.o		\
 			   smp.o smp_spin_table.o topology.o smccc-call.o

deleted file mode 100644
index cf83e61..0000000
@@ -1,28 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * Copyright (C) 2015 ARM Limited
- *
- * Author: Will Deacon <[email protected]>
- */
-
-#include <linux/linkage.h>
-
-/* int __invoke_psci_fn_hvc(u64 function_id, u64 arg0, u64 arg1, u64 arg2) */
-ENTRY(__invoke_psci_fn_hvc)
-	hvc	#0
-	ret
-ENDPROC(__invoke_psci_fn_hvc)
-
-/* int __invoke_psci_fn_smc(u64 function_id, u64 arg0, u64 arg1, u64 arg2) */
-ENTRY(__invoke_psci_fn_smc)
-	smc	#0
-	ret
-ENDPROC(__invoke_psci_fn_smc)

index d24f35d..f25cd79 100644
@@ -13,6 +13,7 @@
 
 #define pr_fmt(fmt) "psci: " fmt
 
+#include <linux/arm-smccc.h>
 #include <linux/errno.h>
 #include <linux/linkage.h>
 #include <linux/of.h>

@@ -58,8 +59,6 @@ struct psci_operations psci_ops;
 
 typedef unsigned long (psci_fn)(unsigned long, unsigned long,
 				unsigned long, unsigned long);
-asmlinkage psci_fn __invoke_psci_fn_hvc;
-asmlinkage psci_fn __invoke_psci_fn_smc;
 static psci_fn *invoke_psci_fn;
 
 enum psci_function {

@@ -107,6 +106,26 @@ bool psci_power_state_is_valid(u32 state)
 	return !(state & ~valid_mask);
 }
 
+static unsigned long __invoke_psci_fn_hvc(unsigned long function_id,
+			unsigned long arg0, unsigned long arg1,
+			unsigned long arg2)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_hvc(function_id, arg0, arg1, arg2, 0, 0, 0, 0, &res);
+	return res.a0;
+}
+
+static unsigned long __invoke_psci_fn_smc(unsigned long function_id,
+			unsigned long arg0, unsigned long arg1,
+			unsigned long arg2)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_smc(function_id, arg0, arg1, arg2, 0, 0, 0, 0, &res);
+	return res.a0;
+}
+
 static int psci_to_linux_errno(int errno)
 {
 	switch (errno) {

1.9.1

I see that you have a lot of people addressed as 'To', which usually means that nobody is going to apply the patches, because none of us knows who should be responsible ;-)

Is the plan still for Russell to pick them up in his tree? Please clarify in the introductory mail what you would like to happen (more review, apply to some tree, get Acks, ...) and change the recipient list accordingly.

Arnd

That is the plan as they are core ARM functionality, but it's now too late for them to be applied prior to Christmas and the merge window. My tree is now closed to new submissions for Christmas.

RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

Thanks, I'll keep that in mind next time.

OK, thanks for the help so far and merry Christmas. I'll make another attempt after the merge window has closed then.

--
Jens

OK, I applied this on top of v4.4-rc6 and pushed it through another round of build[1] and boot[2] testing and things look fine.

Kevin

[1] https://kernelci.org/build/arm-soc/kernel/v4.4-rc6-4-g1ab3cf17f5bd/
[2] https://kernelci.org/boot/all/job/arm-soc/kernel/v4.4-rc6-4-g1ab3cf17f5bd/