[Patch V2]: add hp-timing support and fix syscall.S

[Patch V2]: add hp-timing support and fix syscall.S

[Huang Pei]

All patches are tested on debian 10 mips64el glibc-2.28 and master,
no regression found

add more discription about Patch 3, following Maciej's advice

[PATCH 1/3] mips: add hp-timing support for MIPS R2

[Huang Pei]

MIPS R2 only support 32 bit TSC(AKA "rdhwr %0, $2"), but it should be
enough for glibc

Signed-off-by: Huang Pei <huangpei@loongson.cn>
---
 sysdeps/mips/hp-timing.h | 43 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 sysdeps/mips/hp-timing.h

diff --git a/sysdeps/mips/hp-timing.h b/sysdeps/mips/hp-timing.h
new file mode 100644
index 0000000000..128315d0bf
--- /dev/null
+++ b/sysdeps/mips/hp-timing.h
@@ -0,0 +1,43 @@
+/* High precision, low overhead timing functions. MIPS version.
+   Copyright (C) 2002-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _HP_TIMING_H
+#define _HP_TIMING_H	1
+
+#if __mips_isa_rev >= 2
+/* We always assume having the timestamp register.  */
+#define HP_TIMING_AVAIL		(0)
+#define HP_SMALL_TIMING_AVAIL	(1)
+
+/* We indeed have inlined functions.  */
+#define HP_TIMING_INLINE	(1)
+
+/* We use 32bit values for the times.  */
+typedef unsigned int hp_timing_t;
+
+/* Read the cp0 count, this maybe inaccurate.  */
+#define HP_TIMING_NOW(Var) \
+  ({ unsigned int _count; \
+     asm volatile ("rdhwr\t%0,$2" : "=r" (_count)); \
+     (Var) = _count; })
+
+#include <hp-timing-common.h>
+
+#endif
+
+#endif /* hp-timing.h */
-- 
2.17.1

[PATCH 2/3] mips: make sp 16-byte aligned on N64/N32

[Huang Pei]

MIPS N64/N32 ABI request stack pointer be 16-byte alinged

Signed-off-by: Huang Pei <huangpei@loongson.cn>
---
 sysdeps/unix/sysv/linux/mips/mips64/syscall.S | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/mips/mips64/syscall.S b/sysdeps/unix/sysv/linux/mips/mips64/syscall.S
index a9baff3c17..aab1f389aa 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/syscall.S
+++ b/sysdeps/unix/sysv/linux/mips/mips64/syscall.S
@@ -27,10 +27,10 @@
 
 	.text
 NESTED (syscall, SZREG, ra)
-	.mask 0x00010000, -SZREG
+	.mask 0x00010000, -2 * SZREG
 	.fmask 0x00000000, 0
-	PTR_ADDIU sp, -SZREG
-	cfi_adjust_cfa_offset (SZREG)
+	PTR_ADDIU sp, -2 * SZREG
+	cfi_adjust_cfa_offset (2 * SZREG)
 	REG_S s0, (sp)
 	cfi_rel_offset (s0, 0)
 
@@ -48,8 +48,8 @@ NESTED (syscall, SZREG, ra)
 
 	REG_L s0, (sp)
 	cfi_restore (s0)
-	PTR_ADDIU sp, SZREG
-	cfi_adjust_cfa_offset (-SZREG)
+	PTR_ADDIU sp, 2 * SZREG
+	cfi_adjust_cfa_offset (-2 * 2 * SZREG)
 	bne a3, zero, L(error)
 
 	ret
-- 
2.17.1

[PATCH 3/3] mips: remove register spill

[Huang Pei]

Before Linux/MIPS 2.6.36, kernel expected setting syscall number(aka
"li v0, #sys_number") right precedes "syscall", so the kernel syscall
restart sequence can use CP0 EPC - 4 to restart the syscall, because
kernel DID NOT save v0 during syscall handling. Linux 2.6.36 canceled
this restriction.

See sysdeps/unix/sysv/linux/mips/{mips32/sysdep.h,mips64/sysdep.h,sysdep.h}

Since glibc-2.24 the minimum kernel version is 3.2(much higer than
2.6.36), I think it is OK to remove the ugly register spill in
syscall.S just because the old convention

Signed-off-by: Huang Pei <huangpei@loongson.cn>
---
 sysdeps/unix/sysv/linux/mips/mips64/syscall.S | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/mips/mips64/syscall.S b/sysdeps/unix/sysv/linux/mips/mips64/syscall.S
index aab1f389aa..089524a40b 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/syscall.S
+++ b/sysdeps/unix/sysv/linux/mips/mips64/syscall.S
@@ -27,14 +27,9 @@
 
 	.text
 NESTED (syscall, SZREG, ra)
-	.mask 0x00010000, -2 * SZREG
+	.mask 0x00000000, 0
 	.fmask 0x00000000, 0
-	PTR_ADDIU sp, -2 * SZREG
-	cfi_adjust_cfa_offset (2 * SZREG)
-	REG_S s0, (sp)
-	cfi_rel_offset (s0, 0)
-
-	move s0, a0
+	move v0, a0
 	move a0, a1		/* shift arg1 - arg7.  */
 	move a1, a2
 	move a2, a3
@@ -43,13 +38,8 @@ NESTED (syscall, SZREG, ra)
 	move a5, a6
 	move a6, a7
 
-	move v0, s0		/* Syscall number -> v0 */
 	syscall			/* Do the system call.  */
 
-	REG_L s0, (sp)
-	cfi_restore (s0)
-	PTR_ADDIU sp, 2 * SZREG
-	cfi_adjust_cfa_offset (-2 * 2 * SZREG)
 	bne a3, zero, L(error)
 
 	ret
-- 
2.17.1