On Mon, Feb 07, 2005 at 11:39:12AM -0800, David Daney wrote:
> > offset("#define PT_SCRATCH0 ", struct pt_regs, pad0[4]);
> > offset("#define PT_SCRATCH1 ", struct pt_regs, pad0[5]);
> >
> >I am thinking of testing a patch where I change them to:
> >
> > offset("#define PT_SCRATCH0 ", struct pt_regs, pad0[0]);
> > offset("#define PT_SCRATCH1 ", struct pt_regs, pad0[1]);
> >
> >Any needed argument registers are already saved in and restored from the
> >regs array so overwriting the stack area reserved for them should be OK.
> >
> I now think that is bogus reasoning as the first four slots can be
> clobbered by the compiler.
>
> It seems that t2 must be saved somewhere in the regs list. I am not
> sure what the problem with PT_R1(sp) was, but it seems like a good
> candidate. Perhaps PT_R26 or PT_R27 (k0, k1) would be a better place to
> store t2 as I don't think k0 or k1 are ever stored.
I was always planning to backport the newer fix from 2.6 which is simply
storing the value in a caller saved register. You now reminded me of
that omission ;-)
Patch below,
Ralf
Index: arch/mips/kernel/scall_o32.S
===================================================================
RCS file: /home/cvs/linux/arch/mips/kernel/Attic/scall_o32.S,v
retrieving revision 1.18.2.14
diff -u -r1.18.2.14 scall_o32.S
--- arch/mips/kernel/scall_o32.S 25 Nov 2004 09:43:59 -0000 1.18.2.14
+++ arch/mips/kernel/scall_o32.S 7 Feb 2005 21:12:53 -0000
@@ -121,15 +121,14 @@
trace_a_syscall:
SAVE_STATIC
- sw t2, PT_SCRATCH0(sp)
+ move s0, sp
jal syscall_trace
- lw t2, PT_SCRATCH0(sp)
lw a0, PT_R4(sp) # Restore argument registers
lw a1, PT_R5(sp)
lw a2, PT_R6(sp)
lw a3, PT_R7(sp)
- jalr t2
+ jalr s0
li t0, -EMAXERRNO - 1 # error?
sltu t0, t0, v0
Index: arch/mips/tools/offset.c
===================================================================
RCS file: /home/cvs/linux/arch/mips/tools/Attic/offset.c,v
retrieving revision 1.16.4.12
diff -u -r1.16.4.12 offset.c
--- arch/mips/tools/offset.c 25 Nov 2004 09:43:59 -0000 1.16.4.12
+++ arch/mips/tools/offset.c 7 Feb 2005 21:12:53 -0000
@@ -12,7 +12,6 @@
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/mm.h>
-#include <linux/signal.h>
#include <asm/ptrace.h>
#include <asm/processor.h>
@@ -37,9 +36,6 @@
void output_ptreg_defines(void)
{
text("/* MIPS pt_regs offsets. */");
- offset("#define PT_SCRATCH0 ", struct pt_regs, pad0[4]);
- offset("#define PT_SCRATCH1 ", struct pt_regs, pad0[5]);
-
offset("#define PT_R0 ", struct pt_regs, regs[0]);
offset("#define PT_R1 ", struct pt_regs, regs[1]);
offset("#define PT_R2 ", struct pt_regs, regs[2]);
Index: arch/mips64/kernel/scall_64.S
===================================================================
RCS file: /home/cvs/linux/arch/mips64/kernel/Attic/scall_64.S,v
retrieving revision 1.20.2.20
diff -u -r1.20.2.20 scall_64.S
--- arch/mips64/kernel/scall_64.S 25 Nov 2004 09:43:59 -0000 1.20.2.20
+++ arch/mips64/kernel/scall_64.S 7 Feb 2005 21:12:53 -0000
@@ -102,15 +102,14 @@
trace_a_syscall:
SAVE_STATIC
- sd t2, PT_SCRATCH0(sp)
+ move s0, t2
jal syscall_trace
- ld t2, PT_SCRATCH0(sp)
ld a0, PT_R4(sp) # Restore argument registers
ld a1, PT_R5(sp)
ld a2, PT_R6(sp)
ld a3, PT_R7(sp)
- jalr t2
+ jalr s0
li t0, -EMAXERRNO - 1 # error?
sltu t0, t0, v0
Index: arch/mips64/kernel/scall_n32.S
===================================================================
RCS file: /home/cvs/linux/arch/mips64/kernel/Attic/scall_n32.S,v
retrieving revision 1.2.2.17
diff -u -r1.2.2.17 scall_n32.S
--- arch/mips64/kernel/scall_n32.S 25 Nov 2004 09:43:59 -0000 1.2.2.17
+++ arch/mips64/kernel/scall_n32.S 7 Feb 2005 21:12:53 -0000
@@ -106,15 +106,14 @@
trace_a_syscall:
SAVE_STATIC
- sd t2, PT_SCRATCH0(sp)
+ move s0, t2
jal syscall_trace
- ld t2, PT_SCRATCH0(sp)
ld a0, PT_R4(sp) # Restore argument registers
ld a1, PT_R5(sp)
ld a2, PT_R6(sp)
ld a3, PT_R7(sp)
- jalr t2
+ jalr s0
li t0, -EMAXERRNO - 1 # error?
sltu t0, t0, v0
Index: arch/mips64/kernel/scall_o32.S
===================================================================
RCS file: /home/cvs/linux/arch/mips64/kernel/Attic/scall_o32.S,v
retrieving revision 1.48.2.33
diff -u -r1.48.2.33 scall_o32.S
--- arch/mips64/kernel/scall_o32.S 25 Nov 2004 09:43:59 -0000 1.48.2.33
+++ arch/mips64/kernel/scall_o32.S 7 Feb 2005 21:12:53 -0000
@@ -118,9 +118,8 @@
sd a6, PT_R10(sp)
sd a7, PT_R11(sp)
- sd t2, PT_SCRATCH0(sp)
+ move s0, t2
jal syscall_trace
- ld t2, PT_SCRATCH0(sp)
ld a0, PT_R4(sp) # Restore argument registers
ld a1, PT_R5(sp)
@@ -129,7 +128,7 @@
ld a4, PT_R8(sp)
ld a5, PT_R9(sp)
- jalr t2
+ jalr s0
li t0, -EMAXERRNO - 1 # error?
sltu t0, t0, v0
