[PATCH v2 0/3] Allow accessing CSR using CSR number

[PATCH v2 0/3] Allow accessing CSR using CSR number

[Anup Patel]

This patch series adds support to access CSR using both CSR name and
CSR numbers.

Also, we should prefer accessing CSRs using their CSR numbers because:
1. It compiles fine with older toolchains.
2. We can use latest CSR names in #define macro names of CSR numbers
   as-per RISC-V spec. (e.g. sptbr => CSR_SATP, sbadaddr => CSR_STVAL, etc.)
3. We can access newly added CSRs even if toolchain does not recognize
   newly addes CSRs by name. (e.g. BSSTATUS, BSIE, SSIP, etc.)

The patchset can be found in riscv_csr_number_v2 branch of
https//github.com/avpatel/linux.git

Changes since v1:
 - Squash PATCH2 into cpatch3
 - Added new PATCH2 to add interrupt related SCAUSE defines
   in asm/encoding.h

Anup Patel (3):
  RISC-V: Add separate asm/encoding.h for spec related defines
  RISC-V: Add interrupt related SCAUSE defines in asm/encoding.h
  RISC-V: Access CSRs using CSR numbers

 arch/riscv/include/asm/csr.h         | 67 +++-----------------
 arch/riscv/include/asm/encoding.h    | 95 ++++++++++++++++++++++++++++
 arch/riscv/include/asm/irqflags.h    | 10 +--
 arch/riscv/include/asm/mmu_context.h |  7 +-
 arch/riscv/kernel/entry.S            | 22 +++----
 arch/riscv/kernel/head.S             | 12 ++--
 arch/riscv/kernel/irq.c              |  9 +--
 arch/riscv/kernel/perf_event.c       |  4 +-
 arch/riscv/kernel/smp.c              |  2 +-
 arch/riscv/kernel/traps.c            |  6 +-
 arch/riscv/mm/fault.c                |  6 +-
 11 files changed, 139 insertions(+), 101 deletions(-)
 create mode 100644 arch/riscv/include/asm/encoding.h

--
2.17.1

[PATCH v2 1/3] RISC-V: Add separate asm/encoding.h for spec related defines

[Anup Patel]

It's better to have all RISC-V spec related defines in one place
so this patch adds separate asm/encoding.h for such defines which
can be included in assembly as well as C code.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
 arch/riscv/include/asm/csr.h      | 52 +-------------------------
 arch/riscv/include/asm/encoding.h | 62 +++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 51 deletions(-)
 create mode 100644 arch/riscv/include/asm/encoding.h

diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 28a0d1cb374c..8cf698e39463 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -14,57 +14,7 @@
 #ifndef _ASM_RISCV_CSR_H
 #define _ASM_RISCV_CSR_H
 
-#include <linux/const.h>
-
-/* Status register flags */
-#define SR_SIE	_AC(0x00000002, UL) /* Supervisor Interrupt Enable */
-#define SR_SPIE	_AC(0x00000020, UL) /* Previous Supervisor IE */
-#define SR_SPP	_AC(0x00000100, UL) /* Previously Supervisor */
-#define SR_SUM	_AC(0x00040000, UL) /* Supervisor may access User Memory */
-
-#define SR_FS           _AC(0x00006000, UL) /* Floating-point Status */
-#define SR_FS_OFF       _AC(0x00000000, UL)
-#define SR_FS_INITIAL   _AC(0x00002000, UL)
-#define SR_FS_CLEAN     _AC(0x00004000, UL)
-#define SR_FS_DIRTY     _AC(0x00006000, UL)
-
-#define SR_XS           _AC(0x00018000, UL) /* Extension Status */
-#define SR_XS_OFF       _AC(0x00000000, UL)
-#define SR_XS_INITIAL   _AC(0x00008000, UL)
-#define SR_XS_CLEAN     _AC(0x00010000, UL)
-#define SR_XS_DIRTY     _AC(0x00018000, UL)
-
-#ifndef CONFIG_64BIT
-#define SR_SD   _AC(0x80000000, UL) /* FS/XS dirty */
-#else
-#define SR_SD   _AC(0x8000000000000000, UL) /* FS/XS dirty */
-#endif
-
-/* SATP flags */
-#if __riscv_xlen == 32
-#define SATP_PPN     _AC(0x003FFFFF, UL)
-#define SATP_MODE_32 _AC(0x80000000, UL)
-#define SATP_MODE    SATP_MODE_32
-#else
-#define SATP_PPN     _AC(0x00000FFFFFFFFFFF, UL)
-#define SATP_MODE_39 _AC(0x8000000000000000, UL)
-#define SATP_MODE    SATP_MODE_39
-#endif
-
-/* Interrupt Enable and Interrupt Pending flags */
-#define SIE_SSIE _AC(0x00000002, UL) /* Software Interrupt Enable */
-#define SIE_STIE _AC(0x00000020, UL) /* Timer Interrupt Enable */
-#define SIE_SEIE _AC(0x00000200, UL) /* External Interrupt Enable */
-
-#define EXC_INST_MISALIGNED     0
-#define EXC_INST_ACCESS         1
-#define EXC_BREAKPOINT          3
-#define EXC_LOAD_ACCESS         5
-#define EXC_STORE_ACCESS        7
-#define EXC_SYSCALL             8
-#define EXC_INST_PAGE_FAULT     12
-#define EXC_LOAD_PAGE_FAULT     13
-#define EXC_STORE_PAGE_FAULT    15
+#include <asm/encoding.h>
 
 #ifndef __ASSEMBLY__
 
diff --git a/arch/riscv/include/asm/encoding.h b/arch/riscv/include/asm/encoding.h
new file mode 100644
index 000000000000..29699705dc36
--- /dev/null
+++ b/arch/riscv/include/asm/encoding.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2015 Regents of the University of California
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ */
+
+#ifndef _ASM_RISCV_ENCODING_H
+#define _ASM_RISCV_ENCODING_H
+
+#include <linux/const.h>
+
+/* Status register flags */
+#define SR_SIE		_AC(0x00000002, UL) /* Supervisor Interrupt Enable */
+#define SR_SPIE		_AC(0x00000020, UL) /* Previous Supervisor IE */
+#define SR_SPP		_AC(0x00000100, UL) /* Previously Supervisor */
+#define SR_SUM		_AC(0x00040000, UL) /* Supervisor may access User Memory */
+
+#define SR_FS           _AC(0x00006000, UL) /* Floating-point Status */
+#define SR_FS_OFF       _AC(0x00000000, UL)
+#define SR_FS_INITIAL   _AC(0x00002000, UL)
+#define SR_FS_CLEAN     _AC(0x00004000, UL)
+#define SR_FS_DIRTY     _AC(0x00006000, UL)
+
+#define SR_XS           _AC(0x00018000, UL) /* Extension Status */
+#define SR_XS_OFF       _AC(0x00000000, UL)
+#define SR_XS_INITIAL   _AC(0x00008000, UL)
+#define SR_XS_CLEAN     _AC(0x00010000, UL)
+#define SR_XS_DIRTY     _AC(0x00018000, UL)
+
+#ifndef CONFIG_64BIT
+#define SR_SD		_AC(0x80000000, UL) /* FS/XS dirty */
+#else
+#define SR_SD		_AC(0x8000000000000000, UL) /* FS/XS dirty */
+#endif
+
+/* SATP flags */
+#ifndef CONFIG_64BIT
+#define SATP_PPN	_AC(0x003FFFFF, UL)
+#define SATP_MODE_32	_AC(0x80000000, UL)
+#define SATP_MODE	SATP_MODE_32
+#else
+#define SATP_PPN	_AC(0x00000FFFFFFFFFFF, UL)
+#define SATP_MODE_39	_AC(0x8000000000000000, UL)
+#define SATP_MODE	SATP_MODE_39
+#endif
+
+/* Interrupt Enable and Interrupt Pending flags */
+#define SIE_SSIE	_AC(0x00000002, UL) /* Software Interrupt Enable */
+#define SIE_STIE	_AC(0x00000020, UL) /* Timer Interrupt Enable */
+#define SIE_SEIE	_AC(0x00000200, UL) /* External Interrupt Enable */
+
+#define EXC_INST_MISALIGNED	0
+#define EXC_INST_ACCESS		1
+#define EXC_BREAKPOINT		3
+#define EXC_LOAD_ACCESS		5
+#define EXC_STORE_ACCESS	7
+#define EXC_SYSCALL		8
+#define EXC_INST_PAGE_FAULT	12
+#define EXC_LOAD_PAGE_FAULT	13
+#define EXC_STORE_PAGE_FAULT	15
+
+#endif /* _ASM_RISCV_ENCODING_H */
-- 
2.17.1

Re: [PATCH v2 1/3] RISC-V: Add separate asm/encoding.h for spec related defines

[Christoph Hellwig]

On Sat, Apr 13, 2019 at 03:38:35PM +0000, Anup Patel wrote:
> It's better to have all RISC-V spec related defines in one place
> so this patch adds separate asm/encoding.h for such defines which
> can be included in assembly as well as C code.

As per the discussion of version 1 on Saturday I disagree with this
move.  There is both a philosophical and a practical reason for that:

 a) in RISC-V CSR access is really nicely split out into a separate
    number space, just accessed through a few special instructions.
    It has no overlap with the rest of instruction encoding
 b) <asm/csr.h> is pulled into just about every file build in the kernel
    though <asm/irqflags.h>, <asm/switch_to.h> and <asm/thread_info.h>

So even if you want to later add a new <asm/encoding.h> for instruction
encoding details later, I'd rather prefer to keep CSR access separate
from it.

Re: [PATCH v2 1/3] RISC-V: Add separate asm/encoding.h for spec related defines

[Anup Patel]

On Mon, Apr 15, 2019 at 11:19 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Sat, Apr 13, 2019 at 03:38:35PM +0000, Anup Patel wrote:
> > It's better to have all RISC-V spec related defines in one place
> > so this patch adds separate asm/encoding.h for such defines which
> > can be included in assembly as well as C code.
>
> As per the discussion of version 1 on Saturday I disagree with this
> move.  There is both a philosophical and a practical reason for that:
>
>  a) in RISC-V CSR access is really nicely split out into a separate
>     number space, just accessed through a few special instructions.
>     It has no overlap with the rest of instruction encoding
>  b) <asm/csr.h> is pulled into just about every file build in the kernel
>     though <asm/irqflags.h>, <asm/switch_to.h> and <asm/thread_info.h>
>
> So even if you want to later add a new <asm/encoding.h> for instruction
> encoding details later, I'd rather prefer to keep CSR access separate
> from it.

Sure, no problem. I will add asm/encoding.h for instructions later.

Regards,
Anup

[PATCH v2 2/3] RISC-V: Add interrupt related SCAUSE defines in asm/encoding.h

[Anup Patel]

This patch adds SCAUSE interrupt flag and SCAUSE interrupt cause
related defines to asm/encoding.h. We also use these defines in
arch/riscv/kernel/irq.c and express SIE/SIP flag in-terms of
interrupt causes.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
 arch/riscv/include/asm/encoding.h | 25 +++++++++++++++++++++----
 arch/riscv/kernel/irq.c           |  9 +++++----
 2 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/arch/riscv/include/asm/encoding.h b/arch/riscv/include/asm/encoding.h
index 29699705dc36..4f187854fd8b 100644
--- a/arch/riscv/include/asm/encoding.h
+++ b/arch/riscv/include/asm/encoding.h
@@ -44,10 +44,22 @@
 #define SATP_MODE	SATP_MODE_39
 #endif
 
-/* Interrupt Enable and Interrupt Pending flags */
-#define SIE_SSIE	_AC(0x00000002, UL) /* Software Interrupt Enable */
-#define SIE_STIE	_AC(0x00000020, UL) /* Timer Interrupt Enable */
-#define SIE_SEIE	_AC(0x00000200, UL) /* External Interrupt Enable */
+/* SCAUSE */
+#ifdef CONFIG_64BIT
+#define SCAUSE_IRQ_FLAG		_AC(0x8000000000000000, UL)
+#else
+#define SCAUSE_IRQ_FLAG		_AC(0x80000000, UL)
+#endif
+
+#define IRQ_U_SOFT		0
+#define IRQ_S_SOFT		1
+#define IRQ_M_SOFT		3
+#define IRQ_U_TIMER		4
+#define IRQ_S_TIMER		5
+#define IRQ_M_TIMER		7
+#define IRQ_U_EXT		8
+#define IRQ_S_EXT		9
+#define IRQ_M_EXT		11
 
 #define EXC_INST_MISALIGNED	0
 #define EXC_INST_ACCESS		1
@@ -59,4 +71,9 @@
 #define EXC_LOAD_PAGE_FAULT	13
 #define EXC_STORE_PAGE_FAULT	15
 
+/* SIE (Interrupt Enable) and SIP (Interrupt Pending) flags */
+#define SIE_SSIE		(_AC(0x1, UL) << IRQ_S_SOFT)
+#define SIE_STIE		(_AC(0x1, UL) << IRQ_S_TIMER)
+#define SIE_SEIE		(_AC(0x1, UL) << IRQ_S_EXT)
+
 #endif /* _ASM_RISCV_ENCODING_H */
diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
index 48e6b7db83a1..22b8183ae8d4 100644
--- a/arch/riscv/kernel/irq.c
+++ b/arch/riscv/kernel/irq.c
@@ -9,14 +9,15 @@
 #include <linux/irqchip.h>
 #include <linux/irqdomain.h>
 #include <linux/seq_file.h>
+#include <asm/encoding.h>
 #include <asm/smp.h>
 
 /*
  * Possible interrupt causes:
  */
-#define INTERRUPT_CAUSE_SOFTWARE    1
-#define INTERRUPT_CAUSE_TIMER       5
-#define INTERRUPT_CAUSE_EXTERNAL    9
+#define INTERRUPT_CAUSE_SOFTWARE	IRQ_S_SOFT
+#define INTERRUPT_CAUSE_TIMER		IRQ_S_TIMER
+#define INTERRUPT_CAUSE_EXTERNAL	IRQ_S_EXT
 
 /*
  * The high order bit of the trap cause register is always set for
@@ -24,7 +25,7 @@
  * quickly.  The INTERRUPT_CAUSE_* macros don't contain that bit, so we
  * need to mask it off.
  */
-#define INTERRUPT_CAUSE_FLAG	(1UL << (__riscv_xlen - 1))
+#define INTERRUPT_CAUSE_FLAG		SCAUSE_IRQ_FLAG
 
 int arch_show_interrupts(struct seq_file *p, int prec)
 {
-- 
2.17.1

[PATCH v2 3/3] RISC-V: Access CSRs using CSR numbers

[Anup Patel]

We should prefer accessing CSRs using their CSR numbers because:
1. It compiles fine with older toolchains.
2. We can use latest CSR names in #define macro names of CSR numbers
   as-per RISC-V spec.
3. We can access newly added CSRs even if toolchain does not recognize
   newly addes CSRs by name.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
 arch/riscv/include/asm/csr.h         | 15 ++++++++-------
 arch/riscv/include/asm/encoding.h    | 16 ++++++++++++++++
 arch/riscv/include/asm/irqflags.h    | 10 +++++-----
 arch/riscv/include/asm/mmu_context.h |  7 +------
 arch/riscv/kernel/entry.S            | 22 +++++++++++-----------
 arch/riscv/kernel/head.S             | 12 ++++++------
 arch/riscv/kernel/perf_event.c       |  4 ++--
 arch/riscv/kernel/smp.c              |  2 +-
 arch/riscv/kernel/traps.c            |  6 +++---
 arch/riscv/mm/fault.c                |  6 +-----
 10 files changed, 54 insertions(+), 46 deletions(-)

diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 8cf698e39463..6bf5652d3565 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -14,6 +14,7 @@
 #ifndef _ASM_RISCV_CSR_H
 #define _ASM_RISCV_CSR_H
 
+#include <asm/asm.h>
 #include <asm/encoding.h>
 
 #ifndef __ASSEMBLY__
@@ -21,7 +22,7 @@
 #define csr_swap(csr, val)					\
 ({								\
 	unsigned long __v = (unsigned long)(val);		\
-	__asm__ __volatile__ ("csrrw %0, " #csr ", %1"		\
+	__asm__ __volatile__ ("csrrw %0, " __ASM_STR(csr) ", %1"\
 			      : "=r" (__v) : "rK" (__v)		\
 			      : "memory");			\
 	__v;							\
@@ -30,7 +31,7 @@
 #define csr_read(csr)						\
 ({								\
 	register unsigned long __v;				\
-	__asm__ __volatile__ ("csrr %0, " #csr			\
+	__asm__ __volatile__ ("csrr %0, " __ASM_STR(csr)	\
 			      : "=r" (__v) :			\
 			      : "memory");			\
 	__v;							\
@@ -39,7 +40,7 @@
 #define csr_write(csr, val)					\
 ({								\
 	unsigned long __v = (unsigned long)(val);		\
-	__asm__ __volatile__ ("csrw " #csr ", %0"		\
+	__asm__ __volatile__ ("csrw " __ASM_STR(csr) ", %0"	\
 			      : : "rK" (__v)			\
 			      : "memory");			\
 })
@@ -47,7 +48,7 @@
 #define csr_read_set(csr, val)					\
 ({								\
 	unsigned long __v = (unsigned long)(val);		\
-	__asm__ __volatile__ ("csrrs %0, " #csr ", %1"		\
+	__asm__ __volatile__ ("csrrs %0, " __ASM_STR(csr) ", %1"\
 			      : "=r" (__v) : "rK" (__v)		\
 			      : "memory");			\
 	__v;							\
@@ -56,7 +57,7 @@
 #define csr_set(csr, val)					\
 ({								\
 	unsigned long __v = (unsigned long)(val);		\
-	__asm__ __volatile__ ("csrs " #csr ", %0"		\
+	__asm__ __volatile__ ("csrs " __ASM_STR(csr) ", %0"	\
 			      : : "rK" (__v)			\
 			      : "memory");			\
 })
@@ -64,7 +65,7 @@
 #define csr_read_clear(csr, val)				\
 ({								\
 	unsigned long __v = (unsigned long)(val);		\
-	__asm__ __volatile__ ("csrrc %0, " #csr ", %1"		\
+	__asm__ __volatile__ ("csrrc %0, " __ASM_STR(csr) ", %1"\
 			      : "=r" (__v) : "rK" (__v)		\
 			      : "memory");			\
 	__v;							\
@@ -73,7 +74,7 @@
 #define csr_clear(csr, val)					\
 ({								\
 	unsigned long __v = (unsigned long)(val);		\
-	__asm__ __volatile__ ("csrc " #csr ", %0"		\
+	__asm__ __volatile__ ("csrc " __ASM_STR(csr) ", %0"	\
 			      : : "rK" (__v)			\
 			      : "memory");			\
 })
diff --git a/arch/riscv/include/asm/encoding.h b/arch/riscv/include/asm/encoding.h
index 4f187854fd8b..717b823ac110 100644
--- a/arch/riscv/include/asm/encoding.h
+++ b/arch/riscv/include/asm/encoding.h
@@ -76,4 +76,20 @@
 #define SIE_STIE		(_AC(0x1, UL) << IRQ_S_TIMER)
 #define SIE_SEIE		(_AC(0x1, UL) << IRQ_S_EXT)
 
+#define CSR_TIME		0xc01
+#define CSR_INSTRET		0xc02
+#define CSR_SSTATUS		0x100
+#define CSR_SIE			0x104
+#define CSR_STVEC		0x105
+#define CSR_SCOUNTEREN		0x106
+#define CSR_SSCRATCH		0x140
+#define CSR_SEPC		0x141
+#define CSR_SCAUSE		0x142
+#define CSR_STVAL		0x143
+#define CSR_SIP			0x144
+#define CSR_SATP		0x180
+#define CSR_CYCLEH		0xc80
+#define CSR_TIMEH		0xc81
+#define CSR_INSTRETH		0xc82
+
 #endif /* _ASM_RISCV_ENCODING_H */
diff --git a/arch/riscv/include/asm/irqflags.h b/arch/riscv/include/asm/irqflags.h
index 07a3c6d5706f..1a69b3bcd371 100644
--- a/arch/riscv/include/asm/irqflags.h
+++ b/arch/riscv/include/asm/irqflags.h
@@ -21,25 +21,25 @@
 /* read interrupt enabled status */
 static inline unsigned long arch_local_save_flags(void)
 {
-	return csr_read(sstatus);
+	return csr_read(CSR_SSTATUS);
 }
 
 /* unconditionally enable interrupts */
 static inline void arch_local_irq_enable(void)
 {
-	csr_set(sstatus, SR_SIE);
+	csr_set(CSR_SSTATUS, SR_SIE);
 }
 
 /* unconditionally disable interrupts */
 static inline void arch_local_irq_disable(void)
 {
-	csr_clear(sstatus, SR_SIE);
+	csr_clear(CSR_SSTATUS, SR_SIE);
 }
 
 /* get status and disable interrupts */
 static inline unsigned long arch_local_irq_save(void)
 {
-	return csr_read_clear(sstatus, SR_SIE);
+	return csr_read_clear(CSR_SSTATUS, SR_SIE);
 }
 
 /* test flags */
@@ -57,7 +57,7 @@ static inline int arch_irqs_disabled(void)
 /* set interrupt enabled status */
 static inline void arch_local_irq_restore(unsigned long flags)
 {
-	csr_set(sstatus, flags & SR_SIE);
+	csr_set(CSR_SSTATUS, flags & SR_SIE);
 }
 
 #endif /* _ASM_RISCV_IRQFLAGS_H */
diff --git a/arch/riscv/include/asm/mmu_context.h b/arch/riscv/include/asm/mmu_context.h
index 336d60ec5698..98c76c821367 100644
--- a/arch/riscv/include/asm/mmu_context.h
+++ b/arch/riscv/include/asm/mmu_context.h
@@ -83,12 +83,7 @@ static inline void switch_mm(struct mm_struct *prev,
 		cpumask_clear_cpu(cpu, mm_cpumask(prev));
 		cpumask_set_cpu(cpu, mm_cpumask(next));
 
-		/*
-		 * Use the old spbtr name instead of using the current satp
-		 * name to support binutils 2.29 which doesn't know about the
-		 * privileged ISA 1.10 yet.
-		 */
-		csr_write(sptbr, virt_to_pfn(next->pgd) | SATP_MODE);
+		csr_write(CSR_SATP, virt_to_pfn(next->pgd) | SATP_MODE);
 		local_flush_tlb_all();
 
 		flush_icache_deferred(next);
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index fd9b57c8b4ce..1c1ecc238cfa 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -37,11 +37,11 @@
 	 * the kernel thread pointer.  If we came from the kernel, sscratch
 	 * will contain 0, and we should continue on the current TP.
 	 */
-	csrrw tp, sscratch, tp
+	csrrw tp, CSR_SSCRATCH, tp
 	bnez tp, _save_context
 
 _restore_kernel_tpsp:
-	csrr tp, sscratch
+	csrr tp, CSR_SSCRATCH
 	REG_S sp, TASK_TI_KERNEL_SP(tp)
 _save_context:
 	REG_S sp, TASK_TI_USER_SP(tp)
@@ -87,11 +87,11 @@ _save_context:
 	li t0, SR_SUM | SR_FS
 
 	REG_L s0, TASK_TI_USER_SP(tp)
-	csrrc s1, sstatus, t0
-	csrr s2, sepc
-	csrr s3, sbadaddr
-	csrr s4, scause
-	csrr s5, sscratch
+	csrrc s1, CSR_SSTATUS, t0
+	csrr s2, CSR_SEPC
+	csrr s3, CSR_STVAL
+	csrr s4, CSR_SCAUSE
+	csrr s5, CSR_SSCRATCH
 	REG_S s0, PT_SP(sp)
 	REG_S s1, PT_SSTATUS(sp)
 	REG_S s2, PT_SEPC(sp)
@@ -107,8 +107,8 @@ _save_context:
 	.macro RESTORE_ALL
 	REG_L a0, PT_SSTATUS(sp)
 	REG_L a2, PT_SEPC(sp)
-	csrw sstatus, a0
-	csrw sepc, a2
+	csrw CSR_SSTATUS, a0
+	csrw CSR_SEPC, a2
 
 	REG_L x1,  PT_RA(sp)
 	REG_L x3,  PT_GP(sp)
@@ -155,7 +155,7 @@ ENTRY(handle_exception)
 	 * Set sscratch register to 0, so that if a recursive exception
 	 * occurs, the exception vector knows it came from the kernel
 	 */
-	csrw sscratch, x0
+	csrw CSR_SSCRATCH, x0
 
 	/* Load the global pointer */
 .option push
@@ -248,7 +248,7 @@ resume_userspace:
 	 * Save TP into sscratch, so we can find the kernel data structures
 	 * again.
 	 */
-	csrw sscratch, tp
+	csrw CSR_SSCRATCH, tp
 
 restore_all:
 	RESTORE_ALL
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index fe884cd69abd..041492636b45 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -23,7 +23,7 @@
 __INIT
 ENTRY(_start)
 	/* Mask all interrupts */
-	csrw sie, zero
+	csrw CSR_SIE, zero
 
 	/* Load the global pointer */
 .option push
@@ -89,7 +89,7 @@ relocate:
 	/* Point stvec to virtual address of intruction after satp write */
 	la a0, 1f
 	add a0, a0, a1
-	csrw stvec, a0
+	csrw CSR_STVEC, a0
 
 	/* Compute satp for kernel page tables, but don't load it yet */
 	la a2, swapper_pg_dir
@@ -105,12 +105,12 @@ relocate:
 	srl a0, a0, PAGE_SHIFT
 	or a0, a0, a1
 	sfence.vma
-	csrw sptbr, a0
+	csrw CSR_SATP, a0
 .align 2
 1:
 	/* Set trap vector to spin forever to help debug */
 	la a0, .Lsecondary_park
-	csrw stvec, a0
+	csrw CSR_STVEC, a0
 
 	/* Reload the global pointer */
 .option push
@@ -119,7 +119,7 @@ relocate:
 .option pop
 
 	/* Switch to kernel page tables */
-	csrw sptbr, a2
+	csrw CSR_SATP, a2
 
 	ret
 
@@ -130,7 +130,7 @@ relocate:
 
 	/* Set trap vector to spin forever to help debug */
 	la a3, .Lsecondary_park
-	csrw stvec, a3
+	csrw CSR_STVEC, a3
 
 	slli a3, a0, LGREG
 	la a1, __cpu_up_stack_pointer
diff --git a/arch/riscv/kernel/perf_event.c b/arch/riscv/kernel/perf_event.c
index 667ee70defea..91626d9ae5f2 100644
--- a/arch/riscv/kernel/perf_event.c
+++ b/arch/riscv/kernel/perf_event.c
@@ -185,10 +185,10 @@ static inline u64 read_counter(int idx)
 
 	switch (idx) {
 	case RISCV_PMU_CYCLE:
-		val = csr_read(cycle);
+		val = csr_read(CSR_CYCLE);
 		break;
 	case RISCV_PMU_INSTRET:
-		val = csr_read(instret);
+		val = csr_read(CSR_INSTRET);
 		break;
 	default:
 		WARN_ON_ONCE(idx < 0 ||	idx > RISCV_MAX_COUNTERS);
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index 0c41d07ec281..f244c63d29e4 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -89,7 +89,7 @@ void riscv_software_interrupt(void)
 	unsigned long *stats = ipi_data[smp_processor_id()].stats;
 
 	/* Clear pending IPI */
-	csr_clear(sip, SIE_SSIE);
+	csr_clear(CSR_SIP, SIE_SSIE);
 
 	while (true) {
 		unsigned long ops;
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 24a9333dda2c..1b407a9db3fc 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -159,9 +159,9 @@ void __init trap_init(void)
 	 * Set sup0 scratch register to 0, indicating to exception vector
 	 * that we are presently executing in the kernel
 	 */
-	csr_write(sscratch, 0);
+	csr_write(CSR_SSCRATCH, 0);
 	/* Set the exception vector address */
-	csr_write(stvec, &handle_exception);
+	csr_write(CSR_STVEC, &handle_exception);
 	/* Enable all interrupts */
-	csr_write(sie, -1);
+	csr_write(CSR_SIE, -1);
 }
diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index 88401d5125bc..26293bc053a8 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -239,13 +239,9 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
 		 * Do _not_ use "tsk->active_mm->pgd" here.
 		 * We might be inside an interrupt in the middle
 		 * of a task switch.
-		 *
-		 * Note: Use the old spbtr name instead of using the current
-		 * satp name to support binutils 2.29 which doesn't know about
-		 * the privileged ISA 1.10 yet.
 		 */
 		index = pgd_index(addr);
-		pgd = (pgd_t *)pfn_to_virt(csr_read(sptbr)) + index;
+		pgd = (pgd_t *)pfn_to_virt(csr_read(CSR_SATP)) + index;
 		pgd_k = init_mm.pgd + index;
 
 		if (!pgd_present(*pgd_k))
-- 
2.17.1