On Sun, Jan 04, 2004 at 09:05:32PM +0900, Atsushi Nemoto wrote:
> >>>>> On Fri, 2 Jan 2004 20:44:03 +0100, Ralf Baechle <ralf@linux-mips.org> said:
>
> >> Does anybody know why TASK_SIZE is set to 0x7fff8000 and not
> >> 0x80000000 ?
>
> ralf> There is a weird special case were 32-bit code running on a
> ralf> 64-bit kernel with c0_status.ux set will behave differently than
> ralf> on a 32-bit processor or with c0_status.ux clear. The
> ralf> workaround for 64-bit kernels is to leave the top 32kB of the
> ralf> 2GB user virtual address space unused. For sake of symmetry we
> ralf> do this on both 32-bit and 64-bit kernels.
>
> Then, access_ok in 2.6 tree is broken, isn't it?
>
> It seems there should be another definition of USER_DS for
> CONFIG_MIPS32 in 2.6.
Yes, I'm setting USER_DS to 0x80000000 for CONFIG_MIPS32:
--- linux-mips-2.6.orig/include/asm-mips/uaccess.h 2003-11-30 13:59:06.000000000 +0100
+++ linux.work/include/asm-mips/uaccess.h 2004-01-04 21:22:23.000000000 +0100
@@ -42,7 +42,12 @@
#endif /* CONFIG_MIPS64 */
#define KERNEL_DS ((mm_segment_t) { 0UL })
+
+#ifdef CONFIG_MIPS32
+#define USER_DS ((mm_segment_t) { 0x80000000UL })
+#else
#define USER_DS ((mm_segment_t) { -TASK_SIZE })
+#endif
#define VERIFY_READ 0
#define VERIFY_WRITE 1
The USER_DS mask is also used in scall32-o32.S, scall64-64.S and
scall64-032.S. It think it would be cleaner if we replace there also
the ">= 0" check with the "== 0" check and add the correct size as you
suggested:
--- linux-mips-2.6.orig/arch/mips/kernel/scall64-64.S 2003-10-11 00:58:55.000000000 +0200
+++ linux.work/arch/mips/kernel/scall64-64.S 2004-01-04 21:45:45.000000000 +0100
@@ -119,10 +119,10 @@
bnez v0, bad_alignment
LONG_L v1, TI_ADDR_LIMIT($28) # in legal address range?
- LONG_ADDIU a0, a1, 4
+ LONG_ADDIU a0, a1, 3
or a0, a0, a1
and a0, a0, v1
- bltz a0, bad_address
+ bnez a0, bad_address
#ifdef CONFIG_CPU_HAS_LLSC
/* Ok, this is the ll/sc case. World is sane :-) */
--- linux-mips-2.6.orig/arch/mips/kernel/scall32-o32.S 2003-08-26 02:28:51.000000000 +0200
+++ linux.work/arch/mips/kernel/scall32-o32.S 2004-01-04 21:48:39.000000000 +0100
@@ -187,10 +187,10 @@
bnez v0, bad_alignment
lw v1, TI_ADDR_LIMIT($28) # in legal address range?
- addiu a0, a1, 4
+ addiu a0, a1, 3
or a0, a0, a1
and a0, a0, v1
- bltz a0, bad_address
+ bnez a0, bad_address
#ifdef CONFIG_CPU_HAS_LLSC
/* Ok, this is the ll/sc case. World is sane :-) */
@@ -280,11 +280,11 @@
bnez v0, sigsegv
addu v0, t0, 16 # v0 = usp + 16
- addu t1, v0, 12 # 3 32-bit arguments
+ addu t1, v0, 11 # 3 32-bit arguments
lw v1, TI_ADDR_LIMIT($28)
or v0, v0, t1
and v1, v1, v0
- bltz v1, efault
+ bnez v1, efault
move a0, a1 # shift argument registers
move a1, a2
--- linux-mips-2.6.orig/arch/mips/kernel/scall64-64.S 2003-10-11 00:58:55.000000000 +0200
+++ linux.work/arch/mips/kernel/scall64-64.S 2004-01-04 21:45:45.000000000 +0100
@@ -119,10 +119,10 @@
bnez v0, bad_alignment
LONG_L v1, TI_ADDR_LIMIT($28) # in legal address range?
- LONG_ADDIU a0, a1, 4
+ LONG_ADDIU a0, a1, 3
or a0, a0, a1
and a0, a0, v1
- bltz a0, bad_address
+ bnez a0, bad_address
#ifdef CONFIG_CPU_HAS_LLSC
/* Ok, this is the ll/sc case. World is sane :-) */
Dimitri
