[klibc] [klibc:master] Add RISC-V (RV64) port

klibc-bot for Ben Hutchings ben at decadent.org.uk
Fri Jan 18 08:42:12 PST 2019


Commit-ID:  f1c1f4f99e60ac0f855a0582b4aebebfbb0804dc
Gitweb:     http://git.kernel.org/?p=libs/klibc/klibc.git;a=commit;h=f1c1f4f99e60ac0f855a0582b4aebebfbb0804dc
Author:     Ben Hutchings <ben at decadent.org.uk>
AuthorDate: Tue, 17 Jul 2018 02:55:19 +0100
Committer:  Ben Hutchings <ben at decadent.org.uk>
CommitDate: Fri, 18 Jan 2019 03:10:14 +0000

[klibc] Add RISC-V (RV64) port

RISC-V is pretty boring.  I've cribbed most of this from the MIPS and
AArch64 ports.

I ran into difficulty with initialisation of the gp,register, which I
think has to be process-global - the psABI says that signal handlers
can rely on it, and they could come from any module.  This means that
klibc.so and the executable using it need to agree on a single value.
Currently they don't, and this causes gp-relative addressing to go
wrong.

gp-relative addressing is introduced by "relaxation" in the linker,
so I've disabled that for now.

Link: https://www.zytor.com/pipermail/klibc/2018-July/003997.html
Signed-off-by: Ben Hutchings <ben at decadent.org.uk>

---
 .../arch/{arm64 => riscv64}/klibc/archconfig.h     |  6 +--
 .../arch/{mips64 => riscv64}/klibc/archsetjmp.h    | 14 +++---
 .../arch/{cris => riscv64}/klibc/archsignal.h      |  2 +-
 .../arch/{arm64 => riscv64}/klibc/archstat.h       |  0
 usr/include/arch/riscv64/machine/asm.h             | 26 +++++++++++
 usr/klibc/SYSCALLS.def                             |  2 +-
 usr/klibc/arch/{ppc64 => riscv64}/Kbuild           |  8 ++--
 usr/klibc/arch/riscv64/MCONFIG                     | 22 ++++++++++
 usr/klibc/arch/riscv64/crt0.S                      | 22 ++++++++++
 usr/klibc/arch/riscv64/setjmp.S                    | 50 ++++++++++++++++++++++
 usr/klibc/arch/riscv64/syscall.S                   | 13 ++++++
 usr/klibc/arch/{mips => riscv64}/sysstub.ph        | 15 +++----
 12 files changed, 155 insertions(+), 25 deletions(-)

diff --git a/usr/include/arch/arm64/klibc/archconfig.h b/usr/include/arch/riscv64/klibc/archconfig.h
similarity index 64%
copy from usr/include/arch/arm64/klibc/archconfig.h
copy to usr/include/arch/riscv64/klibc/archconfig.h
index 5e2004b..e85a69c 100644
--- a/usr/include/arch/arm64/klibc/archconfig.h
+++ b/usr/include/arch/riscv64/klibc/archconfig.h
@@ -1,5 +1,5 @@
 /*
- * include/arch/arm64/klibc/archconfig.h
+ * include/arch/riscv64/klibc/archconfig.h
  *
  * See include/klibc/sysconfig.h for the options that can be set in
  * this file.
@@ -9,9 +9,7 @@
 #ifndef _KLIBC_ARCHCONFIG_H
 #define _KLIBC_ARCHCONFIG_H
 
-/* Use rt_* signals */
-#define _KLIBC_USE_RT_SIG 1
+/* We have an MMU but no fork() syscall */
 #define _KLIBC_NO_MMU 0
-#define _KLIBC_REAL_VFORK 1
 
 #endif				/* _KLIBC_ARCHCONFIG_H */
diff --git a/usr/include/arch/mips64/klibc/archsetjmp.h b/usr/include/arch/riscv64/klibc/archsetjmp.h
similarity index 67%
copy from usr/include/arch/mips64/klibc/archsetjmp.h
copy to usr/include/arch/riscv64/klibc/archsetjmp.h
index bfca777..97d6b6b 100644
--- a/usr/include/arch/mips64/klibc/archsetjmp.h
+++ b/usr/include/arch/riscv64/klibc/archsetjmp.h
@@ -1,11 +1,12 @@
 /*
- * arch/mips64/include/klibc/archsetjmp.h
+ * arch/riscv64/include/klibc/archsetjmp.h
  */
 
 #ifndef _KLIBC_ARCHSETJMP_H
 #define _KLIBC_ARCHSETJMP_H
 
 struct __jmp_buf {
+	unsigned long __pc;
 	unsigned long __s0;
 	unsigned long __s1;
 	unsigned long __s2;
@@ -14,12 +15,13 @@ struct __jmp_buf {
 	unsigned long __s5;
 	unsigned long __s6;
 	unsigned long __s7;
-	unsigned long __gp;
-	unsigned long __sp;
 	unsigned long __s8;
-	unsigned long __ra;
-} __attribute__ ((aligned(8)));
+	unsigned long __s9;
+	unsigned long __s10;
+	unsigned long __s11;
+	unsigned long __sp;
+};
 
 typedef struct __jmp_buf jmp_buf[1];
 
-#endif				/* _KLIBC_ARCHSETJMP_H */
+#endif				/* _SETJMP_H */
diff --git a/usr/include/arch/cris/klibc/archsignal.h b/usr/include/arch/riscv64/klibc/archsignal.h
similarity index 82%
copy from usr/include/arch/cris/klibc/archsignal.h
copy to usr/include/arch/riscv64/klibc/archsignal.h
index 7fa7454..560a951 100644
--- a/usr/include/arch/cris/klibc/archsignal.h
+++ b/usr/include/arch/riscv64/klibc/archsignal.h
@@ -1,5 +1,5 @@
 /*
- * arch/cris/include/klibc/archsignal.h
+ * arch/riscv/include/klibc/archsignal.h
  *
  * Architecture-specific signal definitions
  *
diff --git a/usr/include/arch/arm64/klibc/archstat.h b/usr/include/arch/riscv64/klibc/archstat.h
similarity index 100%
copy from usr/include/arch/arm64/klibc/archstat.h
copy to usr/include/arch/riscv64/klibc/archstat.h
diff --git a/usr/include/arch/riscv64/machine/asm.h b/usr/include/arch/riscv64/machine/asm.h
new file mode 100644
index 0000000..9effc93
--- /dev/null
+++ b/usr/include/arch/riscv64/machine/asm.h
@@ -0,0 +1,26 @@
+/*
+ * arch/riscv64/include/machine/asm.h
+ *
+ * Mostly cribbed from mips.
+ */
+
+#ifndef _MACHINE_ASM_H
+#define _MACHINE_ASM_H
+
+/*
+ * ENTRY - declare entry point
+ */
+#define ENTRY(symbol)                           \
+	.globl  symbol;                         \
+	.align  2;                              \
+	.type   symbol, @function;              \
+symbol:
+
+/*
+ * END - mark end of function
+ */
+#define END(function)                           \
+	.size   function, . - function
+
+
+#endif				/* _MACHINE_ASM_H */
diff --git a/usr/klibc/SYSCALLS.def b/usr/klibc/SYSCALLS.def
index 64d7b0c..8ebe835 100644
--- a/usr/klibc/SYSCALLS.def
+++ b/usr/klibc/SYSCALLS.def
@@ -21,7 +21,7 @@ void _exit,exit::_exit(int);
 <?!ia64> pid_t clone::__clone(unsigned long, void *);
 <?ia64> pid_t clone::__clone2(unsigned long, void *, void *);
 # if ! _KLIBC_NO_MMU
-<!sparc,sparc64,ia64,arm64> pid_t fork();
+<!sparc,sparc64,ia64,arm64,riscv64> pid_t fork();
 <sparc,sparc64> pid_t fork at forkish();
 #endif
 #if _KLIBC_REAL_VFORK
diff --git a/usr/klibc/arch/ppc64/Kbuild b/usr/klibc/arch/riscv64/Kbuild
similarity index 60%
copy from usr/klibc/arch/ppc64/Kbuild
copy to usr/klibc/arch/riscv64/Kbuild
index a39e91f..242ac5b 100644
--- a/usr/klibc/arch/ppc64/Kbuild
+++ b/usr/klibc/arch/riscv64/Kbuild
@@ -1,8 +1,8 @@
+# -*- makefile -*-
 #
-# klibc files for ppc64
-#
-
-klib-y := setjmp.o syscall.o
+# klibc files for riscv64
 
 always  := crt0.o
 targets := crt0.o
+
+klib-y := setjmp.o syscall.o
diff --git a/usr/klibc/arch/riscv64/MCONFIG b/usr/klibc/arch/riscv64/MCONFIG
new file mode 100644
index 0000000..38703d9
--- /dev/null
+++ b/usr/klibc/arch/riscv64/MCONFIG
@@ -0,0 +1,22 @@
+# -*- makefile -*-
+#
+# arch/riscv64/MCONFIG
+#
+# Special rules for this architecture.  Note that this is actually
+# included from the main Makefile, and that pathnames should be
+# accordingly.
+#
+
+# We should get klibc.so and the executables to agree on what gp
+# should be.  For now, disable gp-relative addressing.
+KLIBCLDFLAGS      = --no-relax
+KLIBCOPTFLAGS	  += -Os -fomit-frame-pointer
+ifeq ($(DEBUG),y)
+KLIBCOPTFLAGS     += -g
+endif
+KLIBCBITSIZE      = 64
+
+# Normal binaries start at 64 KB, so start the libary at 2 MB.
+KLIBCSHAREDFLAGS  =-Ttext 0x00200200
+
+KLIBCARCHINCFLAGS = -I$(KLIBCKERNELOBJ)/arch/riscv/include
diff --git a/usr/klibc/arch/riscv64/crt0.S b/usr/klibc/arch/riscv64/crt0.S
new file mode 100644
index 0000000..76fa3c2
--- /dev/null
+++ b/usr/klibc/arch/riscv64/crt0.S
@@ -0,0 +1,22 @@
+#
+# arch/riscv64/crt0.S
+#
+# Does arch-specific initialization and invokes __libc_init
+# with the appropriate arguments.
+#
+# See __static_init.c or __shared_init.c for the expected
+# arguments.
+#
+
+#include <machine/asm.h>
+
+ENTRY(_start)
+	.option push
+	.option norelax
+	lla	gp, __global_pointer$
+	.option pop
+
+	mv	a0, sp			# Pointer to ELF entry structure
+	mv	a1, zero		# No onexit pointer
+	jal	__libc_init
+END(_start)
diff --git a/usr/klibc/arch/riscv64/setjmp.S b/usr/klibc/arch/riscv64/setjmp.S
new file mode 100644
index 0000000..66e009e
--- /dev/null
+++ b/usr/klibc/arch/riscv64/setjmp.S
@@ -0,0 +1,50 @@
+/*
+ * arch/riscv64/setjmp.S
+ *
+ * setjmp/longjmp for the RISC-V (RV64) architecture
+ *
+ * The jmp_buf is assumed to contain the following, in order:
+ *	pc (ra)
+ *	s0..s11
+ *	sp
+ */
+
+#include <machine/asm.h>
+
+ENTRY(setjmp)
+	sd	ra, 0(a0)
+	sd	s0, 8(a0)
+	sd	s1, 16(a0)
+	sd	s2, 24(a0)
+	sd	s3, 32(a0)
+	sd	s4, 40(a0)
+	sd	s5, 48(a0)
+	sd	s6, 56(a0)
+	sd	s7, 64(a0)
+	sd	s8, 72(a0)
+	sd	s9, 80(a0)
+	sd	s10, 88(a0)
+	sd	s11, 96(a0)
+	sd	sp, 104(a0)
+	mv	a0, zero
+	jr	ra
+END(setjmp)
+
+ENTRY(longjmp)
+	ld	ra, 0(a0)
+	ld	s0, 8(a0)
+	ld	s1, 16(a0)
+	ld	s2, 24(a0)
+	ld	s3, 32(a0)
+	ld	s4, 40(a0)
+	ld	s5, 48(a0)
+	ld	s6, 56(a0)
+	ld	s7, 64(a0)
+	ld	s8, 72(a0)
+	ld	s9, 80(a0)
+	ld	s10, 88(a0)
+	ld	s11, 96(a0)
+	ld	sp, 104(a0)
+	mv	a0, a1
+	jr	ra
+END(longjmp)
diff --git a/usr/klibc/arch/riscv64/syscall.S b/usr/klibc/arch/riscv64/syscall.S
new file mode 100644
index 0000000..89d9bd2
--- /dev/null
+++ b/usr/klibc/arch/riscv64/syscall.S
@@ -0,0 +1,13 @@
+#include <machine/asm.h>
+#include <asm/unistd.h>
+
+ENTRY(__syscall_common)
+	scall
+	li	t0, -4096
+	bleu	a0, t0, 1f
+	neg	a0, a0
+	lui	t0, %hi(errno)
+	sw	a0, %lo(errno)(t0)
+	li	a0, -1
+1:	jr	ra
+END(__syscall_common)
diff --git a/usr/klibc/arch/mips/sysstub.ph b/usr/klibc/arch/riscv64/sysstub.ph
similarity index 52%
copy from usr/klibc/arch/mips/sysstub.ph
copy to usr/klibc/arch/riscv64/sysstub.ph
index 3689529..85c1beb 100644
--- a/usr/klibc/arch/mips/sysstub.ph
+++ b/usr/klibc/arch/riscv64/sysstub.ph
@@ -1,13 +1,12 @@
 # -*- perl -*-
 #
-# arch/mips/sysstub.ph
+# arch/riscv/sysstub.ph
 #
 # Script to generate system call stubs
 #
 
-# On MIPS, most system calls follow the standard convention, with the
-# system call number in r0 (v0), return an error value in r19 (a3) as
-# well as the return value in r0 (v0).
+# On RISC-V, most system calls follow the standard convention, with the
+# system call number in x17 (a7) and the return value in x10 (a0).
 
 sub make_sysstub($$$$$@) {
     my($outputdir, $fname, $type, $sname, $stype, @args) = @_;
@@ -17,12 +16,10 @@ sub make_sysstub($$$$$@) {
     print OUT "#include <machine/asm.h>\n";
     print OUT "#include <asm/unistd.h>\n";
     print OUT "\n";
-    print OUT "\t.set noreorder\n";
-    print OUT "\n";
-    print OUT "LEAF(${fname})\n";
+    print OUT "ENTRY(${fname})\n";
+    print OUT "\tli\ta7, __NR_${sname}\n";
     print OUT "\tj\t__syscall_${stype}\n";
-    print OUT "\t  li\tv0, __NR_${sname}\n";
-    print OUT "\tEND(${fname})\n";
+    print OUT "END(${fname})\n";
     close(OUT);
 }
 


More information about the klibc mailing list