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Subject[PATCH 2/3] MIPS: Correct the 64-bit DSP accumulator register size
Use the `unsigned long' rather than `__u32' type for DSP accumulator 
registers, like with the regular MIPS multiply/divide accumulator and
general-purpose registers, as all are 64-bit in 64-bit implementations
and using a 32-bit data type leads to contents truncation on context
saving.

Update `arch_ptrace' and `compat_arch_ptrace' accordingly, removing
casts that are similarly not used with multiply/divide accumulator or
general-purpose register accesses.

Cc: stable@vger.kernel.org # 2.6.15+
Fixes: e50c0a8fa60d ("Support the MIPS32 / MIPS64 DSP ASE.")
Signed-off-by: Maciej W. Rozycki <macro@mips.com>
---
Hi,

I have no 64-bit DSP hardware handy to verify this change, however some
surely exists and is used to run Linux, as indicated by GDB PR gdb/22286,
<https://sourceware.org/bugzilla/show_bug.cgi?id=22286>, so we better get
it right before people start screaming.

Maciej
---
arch/mips/include/asm/processor.h | 2 +-
arch/mips/kernel/ptrace.c | 2 +-
arch/mips/kernel/ptrace32.c | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)

linux-mips-dsp64.diff
Index: linux-jhogan-test/arch/mips/include/asm/processor.h
===================================================================
--- linux-jhogan-test.orig/arch/mips/include/asm/processor.h 2018-03-21 17:13:52.000000000 +0000
+++ linux-jhogan-test/arch/mips/include/asm/processor.h 2018-05-09 22:35:33.248559000 +0100
@@ -141,7 +141,7 @@ struct mips_fpu_struct {

#define NUM_DSP_REGS 6

-typedef __u32 dspreg_t;
+typedef unsigned long dspreg_t;

struct mips_dsp_state {
dspreg_t dspr[NUM_DSP_REGS];
Index: linux-jhogan-test/arch/mips/kernel/ptrace.c
===================================================================
--- linux-jhogan-test.orig/arch/mips/kernel/ptrace.c 2018-05-09 22:34:00.000000000 +0100
+++ linux-jhogan-test/arch/mips/kernel/ptrace.c 2018-05-09 22:37:45.416608000 +0100
@@ -856,7 +856,7 @@ long arch_ptrace(struct task_struct *chi
goto out;
}
dregs = __get_dsp_regs(child);
- tmp = (unsigned long) (dregs[addr - DSP_BASE]);
+ tmp = dregs[addr - DSP_BASE];
break;
}
case DSP_CONTROL:
Index: linux-jhogan-test/arch/mips/kernel/ptrace32.c
===================================================================
--- linux-jhogan-test.orig/arch/mips/kernel/ptrace32.c 2018-03-21 17:13:52.000000000 +0000
+++ linux-jhogan-test/arch/mips/kernel/ptrace32.c 2018-05-09 22:45:50.924418000 +0100
@@ -142,7 +142,7 @@ long compat_arch_ptrace(struct task_stru
goto out;
}
dregs = __get_dsp_regs(child);
- tmp = (unsigned long) (dregs[addr - DSP_BASE]);
+ tmp = dregs[addr - DSP_BASE];
break;
}
case DSP_CONTROL:
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