[PATCH] m32r: Fix pt_regs for !COFNIG_ISA_DSP_LEVEL2 target

This modification is required to fix debugging function for m32r targets
with !CONFIG_ISA_DSP_LEVEL2, by unifying 'struct pt_regs' and 'struct
sigcontext' size for all M32R ISA.

Some m32r processor core with !CONFIG_ISA_DSP_LEVEL2 configuration has only
single accumulator a0 (ex.  VDEC2 core, M32102 core, etc.), the others with
CONFIG_ISA_DSP_LEVEL2 has two accumulators, a0 and a1.

This means there are two variations of thread context.  So far, we reduced
and changed stackframe size at a syscall for their context size.  However,
this causes a problem that a GDB for processors with CONFIG_ISA_DSP_LEVEL2
cannot be used for processors with !CONFIG_ISA_DSP_LEVEL2.

From the viewpoint of GDB support, we should reduce such variation of
stackframe size for simplicity.

In this patch, dummy members are added to 'struct pt_regs' and 'struct
sigcontext' to adjust their size for !CONFIG_ISA_DSP_LEVEL2.

This modification is also a one step for a GDB update in future.
Currently, on the m32r, GDB can access process's context by using ptrace
functions in a simple way of register by register access.  By unifying
stackframe size, we have a possibility to make use of ptrace functions of
not only a single register access but also block register access,
PTRACE_{GETREGS,PUTREGS}.

However, for this purpose, we might have to modify stackframe structure
some more; for example, PSW (processor status word) register should be
pre-processed before pushing to stack at a syscall, and so on.  In this
case, we must update carefully both kernel and GDB at a time...

Signed-off-by: Hayato Fujiwara <fujiwara@linux-m32r.org>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Cc: Kei Sakamoto <ksakamot@linux-m32r.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 19 insertions, 30 deletions

diff --git a/arch/m32r/kernel/entry.S b/arch/m32r/kernel/entry.S
index 3871b65f0c82..5e4a0c8a5d3c 100644
--- a/arch/m32r/kernel/entry.S
+++ b/arch/m32r/kernel/entry.S
@@ -20,7 +20,7 @@
  * Stack layout in 'ret_from_system_call':
  *      ptrace needs to have all regs on the stack.
  *      if the order here is changed, it needs to be
- *      updated in fork.c:copy_process, signal.c:do_signal,
+ *      updated in fork.c:copy_thread, signal.c:do_signal,
  *      ptrace.c and ptrace.h
  *
  * M32Rx/M32R2                          M32R
@@ -41,18 +41,17 @@
  *       @(0x38,sp) - syscall_nr        ditto
  *       @(0x3c,sp) - acc0h             @(0x3c,sp) - acch
  *       @(0x40,sp) - acc0l             @(0x40,sp) - accl
- *       @(0x44,sp) - acc1h             @(0x44,sp) - psw
- *       @(0x48,sp) - acc1l             @(0x48,sp) - bpc
- *       @(0x4c,sp) - psw               @(0x4c,sp) - bbpsw
- *       @(0x50,sp) - bpc               @(0x50,sp) - bbpc
- *       @(0x54,sp) - bbpsw             @(0x54,sp) - spu (cr3)
- *       @(0x58,sp) - bbpc              @(0x58,sp) - fp (r13)
- *       @(0x5c,sp) - spu (cr3)         @(0x5c,sp) - lr (r14)
- *       @(0x60,sp) - fp (r13)          @(0x60,sp) - spi (cr12)
- *       @(0x64,sp) - lr (r14)          @(0x64,sp) - orig_r0
- *       @(0x68,sp) - spi (cr2)
- *       @(0x6c,sp) - orig_r0
- *
+ *       @(0x44,sp) - acc1h             @(0x44,sp) - dummy_acc1h
+ *       @(0x48,sp) - acc1l             @(0x48,sp) - dummy_acc1l
+ *       @(0x4c,sp) - psw               ditto
+ *       @(0x50,sp) - bpc               ditto
+ *       @(0x54,sp) - bbpsw             ditto
+ *       @(0x58,sp) - bbpc              ditto
+ *       @(0x5c,sp) - spu (cr3)         ditto
+ *       @(0x60,sp) - fp (r13)          ditto
+ *       @(0x64,sp) - lr (r14)          ditto
+ *       @(0x68,sp) - spi (cr2)         ditto
+ *       @(0x6c,sp) - orig_r0           ditto
  */
 
 #include <linux/config.h>
@@ -102,6 +101,12 @@
 #define ACC0L(reg)              @(0x40,reg)
 #define ACC1H(reg)              @(0x44,reg)
 #define ACC1L(reg)              @(0x48,reg)
+#elif defined(CONFIG_ISA_M32R2) || defined(CONFIG_ISA_M32R)
+#define ACCH(reg)               @(0x3C,reg)
+#define ACCL(reg)               @(0x40,reg)
+#else
+#error unknown isa configuration
+#endif
 #define PSW(reg)                @(0x4C,reg)
 #define BPC(reg)                @(0x50,reg)
 #define BBPSW(reg)              @(0x54,reg)
@@ -111,21 +116,6 @@
 #define LR(reg)                 @(0x64,reg)
 #define SP(reg)                 @(0x68,reg)
 #define ORIG_R0(reg)            @(0x6C,reg)
-#elif defined(CONFIG_ISA_M32R2) || defined(CONFIG_ISA_M32R)
-#define ACCH(reg)               @(0x3C,reg)
-#define ACCL(reg)               @(0x40,reg)
-#define PSW(reg)                @(0x44,reg)
-#define BPC(reg)                @(0x48,reg)
-#define BBPSW(reg)              @(0x4C,reg)
-#define BBPC(reg)               @(0x50,reg)
-#define SPU(reg)                @(0x54,reg)
-#define FP(reg)                 @(0x58,reg)  /* FP = R13 */
-#define LR(reg)                 @(0x5C,reg)
-#define SP(reg)                 @(0x60,reg)
-#define ORIG_R0(reg)            @(0x64,reg)
-#else
-#error unknown isa configuration
-#endif
 
 CF_MASK         = 0x00000001
 TF_MASK         = 0x00000100
@@ -231,7 +221,7 @@ restore_all:
         RESTORE_ALL
 
         # perform work that needs to be done immediately before resumption
-        # r9 : frags
+        # r9 : flags
         ALIGN
 work_pending:
         and3    r4, r9, #_TIF_NEED_RESCHED
@@ -1015,4 +1005,3 @@ ENTRY(sys_call_table)
         .long sys_waitid
 
 syscall_table_size=(.-sys_call_table)
-