Carsten Langgaard wrote:
>
> Hi Karel,
>
> I have tried the root-images tar-files: mipselroot-rh7-20010606 and
> mipsroot-rh7.
> The mipsroot-rh7 (bigendian) root image seem to work fine, but when
> I use the mipselroot-rh7-20010606 (littleendian) I get an illegal
> instruction.
> [cat:179] Illegal instruction 7c010001 at 2ac8b20c ra=00000000.
>
> I'm using a 2.4.3 kernel.
> Anyone got an idea ?
>
> /Carsten
>
Is the userland compiled with MIPS I option? I bet this is the same nasty
MIPS_ATOMIC_SET bug.
Currently, there are three fixes. One is from Florian, which only takes care
of CPUs with ll/sc. Another is from Maceij, which introduces a new syscall,
and some changes in glibc. The thrid is mine, a compromising one. It takes
care of both ll/sc case and non-llsc case, has minimum change, and practically
makes all programs happy.
Ralf, please take at least one of the fixes. Even a not-so-good fix is better
than no fix.
Jun
This is a compromising fix for sysmips(MIPS_ATOMIC_SET, ...). It
forces SIGSYS when the return value is a small negative value. This
limit is OK for glibc.
Jun
diff -Nru linux/arch/mips/kernel/sysmips.c.orig linux/arch/mips/kernel/sysmips.c
--- linux/arch/mips/kernel/sysmips.c.orig Mon Apr 23 11:32:54 2001
+++ linux/arch/mips/kernel/sysmips.c Tue Jun 26 11:50:48 2001
@@ -16,7 +16,7 @@
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/utsname.h>
-
+#include <linux/signal.h>
#include <asm/cachectl.h>
#include <asm/pgalloc.h>
#include <asm/sysmips.h>
@@ -75,53 +75,83 @@
}
case MIPS_ATOMIC_SET: {
-#ifdef CONFIG_CPU_HAS_LLSC
- unsigned int tmp;
+ int *ptr, val, ret, err, tmp;
+ struct siginfo info;
- p = (int *) arg1;
- errno = verify_area(VERIFY_WRITE, p, sizeof(*p));
- if (errno)
- return errno;
- errno = 0;
-
- __asm__(".set\tpush\t\t\t# sysmips(MIPS_ATOMIC, ...)\n\t"
- ".set\tmips2\n\t"
- ".set\tnoat\n\t"
- "1:\tll\t%0, %4\n\t"
- "move\t$1, %3\n\t"
- "2:\tsc\t$1, %1\n\t"
- "beqz\t$1, 1b\n\t"
- ".set\tpop\n\t"
- ".section\t.fixup,\"ax\"\n"
- "3:\tli\t%2, 1\t\t\t# error\n\t"
- ".previous\n\t"
- ".section\t__ex_table,\"a\"\n\t"
- ".word\t1b, 3b\n\t"
- ".word\t2b, 3b\n\t"
- ".previous\n\t"
- : "=&r" (tmp), "=o" (* (u32 *) p), "=r" (errno)
- : "r" (arg2), "o" (* (u32 *) p), "2" (errno)
- : "$1");
+ ptr = (int *)arg1;
+ val = (int)arg2;
- if (errno)
- return -EFAULT;
+ /* Don't emulate unaligned accesses. */
+ if ((int)ptr & 3) {
+ info.si_signo = SIGBUS;
+ info.si_code = BUS_ADRALN;
+ goto fault;
+ }
+
+ /* A zero here saves us three instructions. */
+ err = verify_area(VERIFY_WRITE, ptr, 0);
+ if (err) {
+ info.si_signo = SIGSEGV;
+ info.si_code = SEGV_ACCERR;
+ goto fault;
+ }
- /* We're skipping error handling etc. */
- if (current->ptrace & PT_TRACESYS)
- syscall_trace();
-
- ((struct pt_regs *)&cmd)->regs[2] = tmp;
- ((struct pt_regs *)&cmd)->regs[7] = 0;
-
- __asm__ __volatile__(
- "move\t$29, %0\n\t"
- "j\to32_ret_from_sys_call"
- : /* No outputs */
- : "r" (&cmd));
- /* Unreached */
+#ifdef CONFIG_CPU_HAS_LLSC
+ __asm__(".set mips2\n\t"
+ "1:\n\t"
+ "ll %0,%5\n\t"
+ ".set push\n\t"
+ ".set noreorder\n\t"
+ "beq %0,%4,3f\n\t"
+ " move %3,%4\n"
+ ".set pop\n\t"
+ "2:\n\t"
+ "sc %3,%1\n\t"
+ "beqz %3,1b\n\t"
+ "3:\n\t"
+ ".set mips0\n\t"
+ ".section .fixup,\"ax\"\n"
+ "4:\n\t"
+ "li %2,%7\n\t"
+ "j 3b\n\t"
+ ".previous\n\t"
+ ".section __ex_table,\"a\"\n\t"
+ ".word 1b,4b\n\t"
+ ".word 2b,4b\n\t"
+ ".previous"
+ : "=&r" (ret), "=R" (*ptr), "=r" (err), "=&r" (tmp)
+ : "r" (val), "1" (*ptr), "2" (0), "i" (-EFAULT));
#else
- printk("sys_sysmips(MIPS_ATOMIC_SET, ...) not ready for !CONFIG_CPU_HAS_LLSC\n");
+ save_and_cli(tmp);
+ err = __get_user(ret, ptr);
+ if (ret != val)
+ err |= __put_user(val, ptr); /* No fault
+ unless unwriteable. */
+ restore_flags(tmp);
#endif
+
+ if (err) {
+ info.si_signo = SIGSEGV;
+ info.si_code = SEGV_MAPERR;
+ goto fault;
+ }
+
+ if ( (ret < 0) && (ret >= -EMAXERRNO) ) {
+ info.si_signo = SIGSYS;
+ info.si_code = 0;
+ goto fault;
+ }
+
+ return ret;
+
+fault:
+ /* Go back to SYSCALL. */
+ ((struct pt_regs *)&cmd)->cp0_epc -= 4;
+
+ info.si_addr = (void *)((struct pt_regs *)&cmd)->cp0_epc;
+ force_sig_info(info.si_signo, &info, current);
+
+ return 0;
}
case MIPS_FIXADE:
diff -Nur linux.orig/arch/mips/kernel/Makefile linux/arch/mips/kernel/Makefile
--- linux.orig/arch/mips/kernel/Makefile Mon Apr 9 00:23:08 2001
+++ linux/arch/mips/kernel/Makefile Mon Apr 9 00:23:34 2001
@@ -20,7 +20,7 @@
obj-y += branch.o process.o signal.o entry.o \
traps.o ptrace.o vm86.o ioport.o reset.o \
semaphore.o setup.o syscall.o sysmips.o \
- ipc.o scall_o32.o unaligned.o
+ ipc.o scall_o32.o unaligned.o fast-sysmips.o
obj-$(CONFIG_MODULES) += mips_ksyms.o
ifdef CONFIG_CPU_R3000
@@ -69,5 +69,6 @@
entry.o: entry.S
head.o: head.S
+fast-sysmips.o: fast-sysmips.S
include $(TOPDIR)/Rules.make
diff -Nur linux.orig/arch/mips/kernel/fast-sysmips.S linux/arch/mips/kernel/fast-sysmips.S
--- linux.orig/arch/mips/kernel/fast-sysmips.S Thu Jan 1 01:00:00 1970
+++ linux/arch/mips/kernel/fast-sysmips.S Mon Apr 9 00:28:20 2001
@@ -0,0 +1,85 @@
+/*
+ * MIPS_ATOMIC_SET asm implementation for ll/sc capable cpus
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2001 Florian Lohoff <flo@rfc822.org>
+ *
+ */
+#include <asm/asm.h>
+#include <asm/mipsregs.h>
+#include <asm/regdef.h>
+#include <asm/stackframe.h>
+#include <asm/isadep.h>
+#include <asm/unistd.h>
+#include <asm/sysmips.h>
+#include <asm/offset.h>
+#include <asm/errno.h>
+
+#define PT_TRACESYS 0x00000002
+
+ EXPORT(fast_sysmips)
+
+ .set noreorder
+
+ li t0, MIPS_ATOMIC_SET
+ beq a0, t0, 1f
+ nop
+ j sys_sysmips
+ nop
+
+1:
+
+ # a0 - MIPS_ATOMIC_SET
+ # a1 - mem ptr
+ # a2 - value
+
+ addiu sp, sp, -8 # Reserve space
+ sw a0, (sp) # Save arg0
+
+ addiu a0, a1, 4 # addr+size
+ ori v0, a1, 4 # addr | size
+ lw v1, THREAD_CURDS(gp) # current->thread.current_ds
+ or v0, v0, a0 # addr | size | (addr+size)
+ and v1, v1, v0 # (mask)&(addr | size | (addr+size)
+ bltz v1, 5f
+ nop
+
+2:
+ ll v0, (a1)
+ move t0, a2
+ sc t0, (a1)
+ beqz t0, 2b
+ nop
+
+ sw v0, PT_R2+8(sp) # Result value
+ sw zero, PT_R7+8(sp) # Success indicator
+
+ lw t0, TASK_PTRACE(gp) # syscall tracing enabled?
+ andi t0, PT_TRACESYS
+ bnez t0, 3f
+ nop
+
+4:
+ lw a0, (sp) # Restore arg0
+ addiu sp, sp, 8 # Restore sp
+
+ j o32_ret_from_sys_call
+ nop
+
+3:
+ sw ra, 4(sp)
+ jal syscall_trace
+ nop
+ lw ra, 4(sp)
+ j 4b
+ nop
+
+5:
+ lw a0, (sp) # Restore arg0
+ addiu sp, sp, 8 # Restore sp
+ j ra
+ li v0, -EFAULT
+
diff -Nur linux.orig/arch/mips/kernel/irix5sys.h linux/arch/mips/kernel/irix5sys.h
--- linux.orig/arch/mips/kernel/irix5sys.h Mon Apr 9 00:16:29 2001
+++ linux/arch/mips/kernel/irix5sys.h Sun Apr 8 21:21:16 2001
@@ -69,7 +69,7 @@
SYS(irix_getgid, 0) /* 1047 getgid() V*/
SYS(irix_unimp, 0) /* 1048 (XXX IRIX 4 ssig) V*/
SYS(irix_msgsys, 6) /* 1049 sys_msgsys V*/
-SYS(sys_sysmips, 4) /* 1050 sysmips() HV*/
+SYS(fast_sysmips, 4) /* 1050 sysmips() HV*/
SYS(irix_unimp, 0) /* 1051 XXX sysacct() IV*/
SYS(irix_shmsys, 5) /* 1052 sys_shmsys V*/
SYS(irix_semsys, 0) /* 1053 sys_semsys V*/
diff -Nur linux.orig/arch/mips/kernel/syscalls.h linux/arch/mips/kernel/syscalls.h
--- linux.orig/arch/mips/kernel/syscalls.h Mon Apr 9 00:16:30 2001
+++ linux/arch/mips/kernel/syscalls.h Sun Apr 8 21:21:43 2001
@@ -163,7 +163,7 @@
SYS(sys_writev, 3)
SYS(sys_cacheflush, 3)
SYS(sys_cachectl, 3)
-SYS(sys_sysmips, 4)
+SYS(fast_sysmips, 4)
SYS(sys_ni_syscall, 0) /* 4150 */
SYS(sys_getsid, 1)
SYS(sys_fdatasync, 0)
