[PATCH v3 1/5] RISC-V: Build tishift only on 64-bit

[PATCH v3 1/5] RISC-V: Build tishift only on 64-bit

[Zong Li]

Only RV64 supports 128 integer size.

Signed-off-by: Zong Li <zong@andestech.com>
---
 arch/riscv/lib/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
index 445ec84..5739bd0 100644
--- a/arch/riscv/lib/Makefile
+++ b/arch/riscv/lib/Makefile
@@ -2,6 +2,7 @@ lib-y	+= delay.o
 lib-y	+= memcpy.o
 lib-y	+= memset.o
 lib-y	+= uaccess.o
-lib-y	+= tishift.o
+
+lib-(CONFIG_64BIT) += tishift.o
 
 lib-$(CONFIG_32BIT) += udivdi3.o
-- 
2.7.4

[PATCH v3 2/5] RISC-V: Use swiotlb on RV64 only

[Zong Li]

Only RV64 supports swiotlb. On RV32, it don't select the SWIOTLB.

Signed-off-by: Zong Li <zong@andestech.com>
---
 arch/riscv/kernel/setup.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index aee6031..6de6584 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -227,7 +227,10 @@ void __init setup_arch(char **cmdline_p)
 	setup_bootmem();
 	paging_init();
 	unflatten_device_tree();
+
+#ifdef CONFIG_SWIOTLB
 	swiotlb_init(1);
+#endif
 
 #ifdef CONFIG_SMP
 	setup_smp();
-- 
2.7.4

[PATCH v3 3/5] lib: Add umoddi3 and udivmoddi4 of GCC library routines

[Zong Li]

Add umoddi3 and udivmoddi4 support for 32-bit.

The RV32 need the umoddi3 to do modulo when the operands are long long
type, like other libraries implementation such as ucmpdi2, lshrdi3 and
so on.

I encounter the undefined reference 'umoddi3' when I use the in
house dma driver, although it is in house driver, but I think that
umoddi3 is a common function for RV32.

The udivmoddi4 and umoddi3 are copies from libgcc in gcc. There are other
functions use the udivmoddi4 in libgcc, so I separate the umoddi3 and
udivmoddi4 for flexible extension in the future.

Signed-off-by: Zong Li <zong@andestech.com>
---
 lib/Kconfig      |   3 +
 lib/Makefile     |   1 +
 lib/udivmoddi4.c | 310 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/umoddi3.c    |  32 ++++++
 4 files changed, 346 insertions(+)
 create mode 100644 lib/udivmoddi4.c
 create mode 100644 lib/umoddi3.c

diff --git a/lib/Kconfig b/lib/Kconfig
index a3928d4..d82f206 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -621,3 +621,6 @@ config GENERIC_LIB_CMPDI2
 
 config GENERIC_LIB_UCMPDI2
 	bool
+
+config GENERIC_LIB_UMODDI3
+	bool
diff --git a/lib/Makefile b/lib/Makefile
index ca3f7eb..51bf24d 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -271,3 +271,4 @@ obj-$(CONFIG_GENERIC_LIB_LSHRDI3) += lshrdi3.o
 obj-$(CONFIG_GENERIC_LIB_MULDI3) += muldi3.o
 obj-$(CONFIG_GENERIC_LIB_CMPDI2) += cmpdi2.o
 obj-$(CONFIG_GENERIC_LIB_UCMPDI2) += ucmpdi2.o
+obj-$(CONFIG_GENERIC_LIB_UMODDI3) += umoddi3.o udivmoddi4.o
diff --git a/lib/udivmoddi4.c b/lib/udivmoddi4.c
new file mode 100644
index 0000000..c08bc8a
--- /dev/null
+++ b/lib/udivmoddi4.c
@@ -0,0 +1,310 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see the file COPYING, or write
+ * to the Free Software Foundation, Inc.
+ */
+
+#include <linux/libgcc.h>
+
+#define count_leading_zeros(COUNT, X)   ((COUNT) = __builtin_clz(X))
+
+#define W_TYPE_SIZE 32
+
+#define __ll_B ((unsigned long) 1 << (W_TYPE_SIZE / 2))
+#define __ll_lowpart(t) ((unsigned long) (t) & (__ll_B - 1))
+#define __ll_highpart(t) ((unsigned long) (t) >> (W_TYPE_SIZE / 2))
+
+/* If we still don't have umul_ppmm, define it using plain C. */
+#if !defined(umul_ppmm)
+#define umul_ppmm(w1, w0, u, v)						\
+	do {								\
+		unsigned long __x0, __x1, __x2, __x3;			\
+		unsigned short __ul, __vl, __uh, __vh;			\
+									\
+		__ul = __ll_lowpart(u);					\
+		__uh = __ll_highpart(u);				\
+		__vl = __ll_lowpart(v);					\
+		__vh = __ll_highpart(v);				\
+									\
+		__x0 = (unsigned long) __ul * __vl;			\
+		__x1 = (unsigned long) __ul * __vh;			\
+		__x2 = (unsigned long) __uh * __vl;			\
+		__x3 = (unsigned long) __uh * __vh;			\
+									\
+		__x1 += __ll_highpart(__x0);				\
+		__x1 += __x2;						\
+		if (__x1 < __x2)					\
+			__x3 += __ll_B;					\
+									\
+		(w1) = __x3 + __ll_highpart(__x1);			\
+		(w0) = __ll_lowpart(__x1) * __ll_B + __ll_lowpart(__x0);\
+	} while (0)
+#endif
+
+#if !defined(sub_ddmmss)
+#define sub_ddmmss(sh, sl, ah, al, bh, bl)				\
+	do {								\
+		unsigned long __x;					\
+		__x = (al) - (bl);					\
+		(sh) = (ah) - (bh) - (__x > (al));			\
+		(sl) = __x;						\
+	} while (0)
+#endif
+
+/* Define this unconditionally, so it can be used for debugging. */
+#define __udiv_qrnnd_c(q, r, n1, n0, d)					\
+	do {								\
+		unsigned long __d1, __d0, __q1, __q0;			\
+		unsigned long __r1, __r0, __m;				\
+		__d1 = __ll_highpart(d);				\
+		__d0 = __ll_lowpart(d);				\
+									\
+		__r1 = (n1) % __d1;					\
+		__q1 = (n1) / __d1;					\
+		__m = (unsigned long) __q1 * __d0;			\
+		__r1 = __r1 * __ll_B | __ll_highpart(n0);		\
+		if (__r1 < __m) {					\
+			__q1--, __r1 += (d);				\
+			if (__r1 >= (d))				\
+				if (__r1 < __m)				\
+					__q1--, __r1 += (d);		\
+		}							\
+		__r1 -= __m;						\
+									\
+		__r0 = __r1 % __d1;					\
+		__q0 = __r1 / __d1;					\
+		__m = (unsigned long) __q0 * __d0;			\
+		__r0 = __r0 * __ll_B | __ll_lowpart(n0);		\
+		if (__r0 < __m) {					\
+			__q0--, __r0 += (d);				\
+			if (__r0 >= (d))				\
+				if (__r0 < __m)				\
+					__q0--, __r0 += (d);		\
+		}							\
+		__r0 -= __m;						\
+									\
+		(q) = (unsigned long) __q1 * __ll_B | __q0;		\
+		(r) = __r0;						\
+	} while (0)
+
+/* If udiv_qrnnd was not defined for this processor, use __udiv_qrnnd_c. */
+#if !defined(udiv_qrnnd)
+#define UDIV_NEEDS_NORMALIZATION 1
+#define udiv_qrnnd __udiv_qrnnd_c
+#endif
+
+unsigned long long __udivmoddi4(unsigned long long u, unsigned long long v,
+				unsigned long long *rp)
+{
+	const DWunion nn = {.ll = u };
+	const DWunion dd = {.ll = v };
+	DWunion rr, ww;
+	unsigned long d0, d1, n0, n1, n2;
+	unsigned long q0 = 0, q1 = 0;
+	unsigned long b, bm;
+
+	d0 = dd.s.low;
+	d1 = dd.s.high;
+	n0 = nn.s.low;
+	n1 = nn.s.high;
+
+#if !UDIV_NEEDS_NORMALIZATION
+
+	if (d1 == 0) {
+		if (d0 > n1) {
+			/* 0q = nn / 0D */
+
+			udiv_qrnnd(q0, n0, n1, n0, d0);
+			q1 = 0;
+
+			/* Remainder in n0. */
+		} else {
+			/* qq = NN / 0d */
+
+			if (d0 == 0)
+				/* Divide intentionally by zero. */
+				d0 = 1 / d0;
+
+			udiv_qrnnd(q1, n1, 0, n1, d0);
+			udiv_qrnnd(q0, n0, n1, n0, d0);
+
+			/* Remainder in n0. */
+		}
+
+		if (rp != 0) {
+			rr.s.low = n0;
+			rr.s.high = 0;
+			*rp = rr.ll;
+		}
+
+#else /* UDIV_NEEDS_NORMALIZATION */
+
+	if (d1 == 0) {
+		if (d0 > n1) {
+			/* 0q = nn / 0D */
+
+			count_leading_zeros(bm, d0);
+
+			if (bm != 0) {
+				/*
+				 * Normalize, i.e. make the most significant bit
+				 * of the denominator set.
+				 */
+
+				d0 = d0 << bm;
+				n1 = (n1 << bm) | (n0 >> (W_TYPE_SIZE - bm));
+				n0 = n0 << bm;
+			}
+
+			udiv_qrnnd(q0, n0, n1, n0, d0);
+			q1 = 0;
+
+			/* Remainder in n0 >> bm. */
+		} else {
+			/* qq = NN / 0d */
+
+			if (d0 == 0)
+				/* Divide intentionally by zero. */
+				d0 = 1 / d0;
+
+			count_leading_zeros(bm, d0);
+
+			if (bm == 0) {
+				/*
+				 * From (n1 >= d0) /\ (the most significant bit
+				 * of d0 is set), conclude (the most significant
+				 * bit of n1 is set) /\ (theleading quotient
+				 * digit q1 = 1).
+				 *
+				 * This special case is necessary, not an
+				 * optimization. (Shifts counts of W_TYPE_SIZE
+				 * are undefined.)
+				 */
+
+				n1 -= d0;
+				q1 = 1;
+			} else {
+				/* Normalize. */
+
+				b = W_TYPE_SIZE - bm;
+
+				d0 = d0 << bm;
+				n2 = n1 >> b;
+				n1 = (n1 << bm) | (n0 >> b);
+				n0 = n0 << bm;
+
+				udiv_qrnnd(q1, n1, n2, n1, d0);
+			}
+
+			/* n1 != d0... */
+
+			udiv_qrnnd(q0, n0, n1, n0, d0);
+
+			/* Remainder in n0 >> bm. */
+		}
+
+		if (rp != 0) {
+			rr.s.low = n0 >> bm;
+			rr.s.high = 0;
+			*rp = rr.ll;
+		}
+
+#endif /* UDIV_NEEDS_NORMALIZATION */
+
+	} else {
+		if (d1 > n1) {
+			/* 00 = nn / DD */
+
+			q0 = 0;
+			q1 = 0;
+
+			/* Remainder in n1n0. */
+			if (rp != 0) {
+				rr.s.low = n0;
+				rr.s.high = n1;
+				*rp = rr.ll;
+			}
+		} else {
+			/* 0q = NN / dd */
+
+			count_leading_zeros(bm, d1);
+			if (bm == 0) {
+				/*
+				 * From (n1 >= d1) /\ (the most significant bit
+				 * of d1 is set), conclude (the most significant
+				 * bit of n1 is set) /\ (the quotient digit q0 =
+				 * 0 or 1).
+				 *
+				 * This special case is necessary, not an
+				 * optimization.
+				 */
+
+				/*
+				 * The condition on the next line takes
+				 * advantage of that n1 >= d1 (true due to
+				 * program flow).
+				 */
+				if (n1 > d1 || n0 >= d0) {
+					q0 = 1;
+					sub_ddmmss(n1, n0, n1, n0, d1, d0);
+				} else {
+					q0 = 0;
+				}
+
+				q1 = 0;
+
+				if (rp != 0) {
+					rr.s.low = n0;
+					rr.s.high = n1;
+					*rp = rr.ll;
+				}
+			} else {
+				unsigned long m1, m0;
+				/* Normalize. */
+
+				b = W_TYPE_SIZE - bm;
+
+				d1 = (d1 << bm) | (d0 >> b);
+				d0 = d0 << bm;
+				n2 = n1 >> b;
+				n1 = (n1 << bm) | (n0 >> b);
+				n0 = n0 << bm;
+
+				udiv_qrnnd(q0, n1, n2, n1, d1);
+				umul_ppmm(m1, m0, q0, d0);
+
+				if (m1 > n1 || (m1 == n1 && m0 > n0)) {
+					q0--;
+					sub_ddmmss(m1, m0, m1, m0, d1, d0);
+				}
+
+				q1 = 0;
+
+				/* Remainder in (n1n0 - m1m0) >> bm. */
+				if (rp != 0) {
+					sub_ddmmss(n1, n0, n1, n0, m1, m0);
+					rr.s.low = (n1 << b) | (n0 >> bm);
+					rr.s.high = n1 >> bm;
+					*rp = rr.ll;
+				}
+			}
+		}
+	}
+
+	ww.s.low = q0;
+	ww.s.high = q1;
+
+	return ww.ll;
+}
diff --git a/lib/umoddi3.c b/lib/umoddi3.c
new file mode 100644
index 0000000..d7bbf0f
--- /dev/null
+++ b/lib/umoddi3.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see the file COPYING, or write
+ * to the Free Software Foundation, Inc.
+ */
+
+#include <linux/module.h>
+#include <linux/libgcc.h>
+
+extern unsigned long long __udivmoddi4(unsigned long long u,
+				       unsigned long long v,
+				       unsigned long long *rp);
+
+unsigned long long __umoddi3(unsigned long long u, unsigned long long v)
+{
+	unsigned long long w;
+	(void)__udivmoddi4(u, v, &w);
+	return w;
+}
+EXPORT_SYMBOL(__umoddi3);
-- 
2.7.4

[PATCH v3 4/5] RISC-V: Select GENERIC_LIB_UMODDI3 on RV32

[Zong Li]

On 32-bit, it need to use __umoddi3 by some drivers.

Signed-off-by: Zong Li <zong@andestech.com>
---
 arch/riscv/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index a344980..dc262fa 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -108,6 +108,7 @@ config ARCH_RV32I
 	select GENERIC_LIB_ASHRDI3
 	select GENERIC_LIB_LSHRDI3
 	select GENERIC_LIB_UCMPDI2
+	select GENERIC_LIB_UMODDI3
 
 config ARCH_RV64I
 	bool "RV64I"
-- 
2.7.4

[PATCH v3 5/5] RISC-V: Avoid corrupting the upper 32-bit of phys_addr_t in ioremap

[Zong Li]

From: Vincent Chen <vincentc@andestech.com>

For 32bit, the upper 32-bit of phys_addr_t will be flushed to zero
after AND with PAGE_MASK because the data type of PAGE_MASK is
unsigned long. To fix this problem, the page alignment is done by
subtracting the page offset instead of AND with PAGE_MASK.

Signed-off-by: Vincent Chen <vincentc@andestech.com>
---
 arch/riscv/mm/ioremap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/mm/ioremap.c b/arch/riscv/mm/ioremap.c
index 70ef272..bd2f2db 100644
--- a/arch/riscv/mm/ioremap.c
+++ b/arch/riscv/mm/ioremap.c
@@ -42,7 +42,7 @@ static void __iomem *__ioremap_caller(phys_addr_t addr, size_t size,
 
 	/* Page-align mappings */
 	offset = addr & (~PAGE_MASK);
-	addr &= PAGE_MASK;
+	addr -= offset;
 	size = PAGE_ALIGN(size + offset);
 
 	area = get_vm_area_caller(size, VM_IOREMAP, caller);
-- 
2.7.4

Re: [PATCH v3 1/5] RISC-V: Build tishift only on 64-bit

[Christoph Hellwig]

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH v3 2/5] RISC-V: Use swiotlb on RV64 only

[Christoph Hellwig]

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH v3 3/5] lib: Add umoddi3 and udivmoddi4 of GCC library routines

[Christoph Hellwig]

> The udivmoddi4 and umoddi3 are copies from libgcc in gcc. There are other
> functions use the udivmoddi4 in libgcc, so I separate the umoddi3 and
> udivmoddi4 for flexible extension in the future.

Can you please mention which exact version of an external projected
you imported things from?  That will generally help if/when someone
has to dig into diverging versions.

> +++ b/lib/udivmoddi4.c
> @@ -0,0 +1,310 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, see the file COPYING, or write
> + * to the Free Software Foundation, Inc.
> + */

The SPDX tag was supposed to replace this boiler plate.  On the other
hand I'm surpriced there is no Copyright statement here - the FSF is
usually very good about having them uptodate in every GNU project.

Re: [PATCH v3 4/5] RISC-V: Select GENERIC_LIB_UMODDI3 on RV32

[Christoph Hellwig]

On Tue, Oct 02, 2018 at 04:52:30PM +0800, Zong Li wrote:
> On 32-bit, it need to use __umoddi3 by some drivers.
> 
> Signed-off-by: Zong Li <zong@andestech.com>

Which drivers?

Re: [PATCH v3 5/5] RISC-V: Avoid corrupting the upper 32-bit of phys_addr_t in ioremap

[Christoph Hellwig]

On Tue, Oct 02, 2018 at 04:52:31PM +0800, Zong Li wrote:
> From: Vincent Chen <vincentc@andestech.com>
> 
> For 32bit, the upper 32-bit of phys_addr_t will be flushed to zero
> after AND with PAGE_MASK because the data type of PAGE_MASK is
> unsigned long. To fix this problem, the page alignment is done by
> subtracting the page offset instead of AND with PAGE_MASK.
> 
> Signed-off-by: Vincent Chen <vincentc@andestech.com>

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

(and I'm pretty sure I reviewed this before..)

Re: [PATCH v3 3/5] lib: Add umoddi3 and udivmoddi4 of GCC library routines

[Palmer Dabbelt]

On Tue, 02 Oct 2018 07:50:41 PDT (-0700), Christoph Hellwig wrote:
>> The udivmoddi4 and umoddi3 are copies from libgcc in gcc. There are other
>> functions use the udivmoddi4 in libgcc, so I separate the umoddi3 and
>> udivmoddi4 for flexible extension in the future.
>
> Can you please mention which exact version of an external projected
> you imported things from?  That will generally help if/when someone
> has to dig into diverging versions.
>
>> +++ b/lib/udivmoddi4.c
>> @@ -0,0 +1,310 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +
>> +/*
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * 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.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program; if not, see the file COPYING, or write
>> + * to the Free Software Foundation, Inc.
>> + */
>
> The SPDX tag was supposed to replace this boiler plate.  On the other
> hand I'm surpriced there is no Copyright statement here - the FSF is
> usually very good about having them uptodate in every GNU project.

I suggested he import the gcc-4.2.1 version, which has a big copyright notice

    /* More subroutines needed by GCC output code on some machines.  */
    /* Compile this one with gcc.  */
    /* Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
       2000, 2001, 2002, 2003, 2004, 2005  Free Software Foundation, Inc.
    
    This file is part of GCC.
    
    GCC is free software; you can redistribute it and/or modify it under
    the terms of the GNU General Public License as published by the Free
    Software Foundation; either version 2, or (at your option) any later
    version.
    
    In addition to the permissions in the GNU General Public License, the
    Free Software Foundation gives you unlimited permission to link the
    compiled version of this file into combinations with other programs,
    and to distribute those combinations without any restriction coming
    from the use of this file.  (The General Public License restrictions
    do apply in other respects; for example, they cover modification of
    the file, and distribution when not linked into a combine
    executable.)
    
    GCC 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.
    
    You should have received a copy of the GNU General Public License
    along with GCC; see the file COPYING.  If not, write to the Free
    Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
    02110-1301, USA.  */

so it looks like something went wrong here.  Zong: did you go back and 
re-construct this function from the GPLv2 source?

Re: [PATCH v3 3/5] lib: Add umoddi3 and udivmoddi4 of GCC library routines

[Zong Li]

Palmer Dabbelt <palmer@sifive.com> 於 2018年10月2日 週二 下午11:02寫道：
>
> On Tue, 02 Oct 2018 07:50:41 PDT (-0700), Christoph Hellwig wrote:
> >> The udivmoddi4 and umoddi3 are copies from libgcc in gcc. There are other
> >> functions use the udivmoddi4 in libgcc, so I separate the umoddi3 and
> >> udivmoddi4 for flexible extension in the future.
> >
> > Can you please mention which exact version of an external projected
> > you imported things from?  That will generally help if/when someone
> > has to dig into diverging versions.
> >
> >> +++ b/lib/udivmoddi4.c
> >> @@ -0,0 +1,310 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +
> >> +/*
> >> + * This program is free software; you can redistribute it and/or modify
> >> + * it under the terms of the GNU General Public License as published by
> >> + * the Free Software Foundation; either version 2 of the License, or
> >> + * (at your option) any later version.
> >> + *
> >> + * 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.
> >> + *
> >> + * You should have received a copy of the GNU General Public License
> >> + * along with this program; if not, see the file COPYING, or write
> >> + * to the Free Software Foundation, Inc.
> >> + */
> >
> > The SPDX tag was supposed to replace this boiler plate.  On the other
> > hand I'm surpriced there is no Copyright statement here - the FSF is
> > usually very good about having them uptodate in every GNU project.
>
> I suggested he import the gcc-4.2.1 version, which has a big copyright notice
>
>     /* More subroutines needed by GCC output code on some machines.  */
>     /* Compile this one with gcc.  */
>     /* Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
>        2000, 2001, 2002, 2003, 2004, 2005  Free Software Foundation, Inc.
>
>     This file is part of GCC.
>
>     GCC is free software; you can redistribute it and/or modify it under
>     the terms of the GNU General Public License as published by the Free
>     Software Foundation; either version 2, or (at your option) any later
>     version.
>
>     In addition to the permissions in the GNU General Public License, the
>     Free Software Foundation gives you unlimited permission to link the
>     compiled version of this file into combinations with other programs,
>     and to distribute those combinations without any restriction coming
>     from the use of this file.  (The General Public License restrictions
>     do apply in other respects; for example, they cover modification of
>     the file, and distribution when not linked into a combine
>     executable.)
>
>     GCC 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.
>
>     You should have received a copy of the GNU General Public License
>     along with GCC; see the file COPYING.  If not, write to the Free
>     Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
>     02110-1301, USA.  */
>
> so it looks like something went wrong here.  Zong: did you go back and
> re-construct this function from the GPLv2 source?

Yes, I re-construct this function from GCC 4.2.1. The copyright part,
I referred to the other GCC routine copies in kernel such as ucmpdi2,
muldi3, ashldi3 and so on, I found they removed the 'GCC' string, so I
use the same copyright from these files.
I will re-write the copyright part and submit the next version. Thanks
to all for help.

Re: [PATCH v3 5/5] RISC-V: Avoid corrupting the upper 32-bit of phys_addr_t in ioremap

[Zong Li]

Christoph Hellwig <hch@infradead.org> 於 2018年10月2日 週二 下午10:51寫道：
>
> On Tue, Oct 02, 2018 at 04:52:31PM +0800, Zong Li wrote:
> > From: Vincent Chen <vincentc@andestech.com>
> >
> > For 32bit, the upper 32-bit of phys_addr_t will be flushed to zero
> > after AND with PAGE_MASK because the data type of PAGE_MASK is
> > unsigned long. To fix this problem, the page alignment is done by
> > subtracting the page offset instead of AND with PAGE_MASK.
> >
> > Signed-off-by: Vincent Chen <vincentc@andestech.com>
>
> Looks good,
>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
>
> (and I'm pretty sure I reviewed this before..)

Hi Christoph,

Very sorry about that. I didn't notice I lose these review tags. Could
you please help to review again in version 4 patches? Thank you.

Regards,
Zong