powerpc: Make single-stepping emulation (mostly) usable on 32-bit

The sc instruction emulation can't be done the same way on 32-bit
as 64-bit yet, but this should work OK.

Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index e79123d..666c2aa 100644 (file)
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -10,13 +10,18 @@
  */
 #include <linux/kernel.h>
 #include <linux/ptrace.h>
+#include <linux/config.h>
 #include <asm/sstep.h>
 #include <asm/processor.h>
 
 extern char system_call_common[];
 
+#ifdef CONFIG_PPC64
 /* Bits in SRR1 that are copied from MSR */
 #define MSR_MASK       0xffffffff87c0ffff
+#else
+#define MSR_MASK       0x87c0ffff
+#endif
 
 /*
  * Determine whether a conditional branch instruction would branch.
@@ -66,6 +71,7 @@ int emulate_step(struct pt_regs *regs, unsigned int instr)
                if (branch_taken(instr, regs))
                        regs->nip = imm;
                return 1;
+#ifdef CONFIG_PPC64
        case 17:        /* sc */
                /*
                 * N.B. this uses knowledge about how the syscall
@@ -79,6 +85,7 @@ int emulate_step(struct pt_regs *regs, unsigned int instr)
                regs->nip = (unsigned long) &system_call_common;
                regs->msr = MSR_KERNEL;
                return 1;
+#endif
        case 18:        /* b */
                imm = instr & 0x03fffffc;
                if (imm & 0x02000000)
@@ -121,6 +128,15 @@ int emulate_step(struct pt_regs *regs, unsigned int instr)
                        if ((regs->msr & MSR_SF) == 0)
                                regs->nip &= 0xffffffffUL;
                        return 1;
+               case 0x124:     /* mtmsr */
+                       imm = regs->gpr[rd];
+                       if ((imm & MSR_RI) == 0)
+                               /* can't step mtmsr that would clear MSR_RI */
+                               return -1;
+                       regs->msr = imm;
+                       regs->nip += 4;
+                       return 1;
+#ifdef CONFIG_PPC64
                case 0x164:     /* mtmsrd */
                        /* only MSR_EE and MSR_RI get changed if bit 15 set */
                        /* mtmsrd doesn't change MSR_HV and MSR_ME */
@@ -135,6 +151,7 @@ int emulate_step(struct pt_regs *regs, unsigned int instr)
                        if ((imm & MSR_SF) == 0)
                                regs->nip &= 0xffffffffUL;
                        return 1;
+#endif
                }
        }
        return 0;

diff --git a/include/asm-powerpc/reg.h b/include/asm-powerpc/reg.h
index 68058d7..bfb45a4 100644 (file)
--- a/include/asm-powerpc/reg.h
+++ b/include/asm-powerpc/reg.h
@@ -51,9 +51,17 @@
 #define __MASK(X)      (1UL<<(X))
 #endif
 
+#ifdef CONFIG_PPC64
 #define MSR_SF         __MASK(MSR_SF_LG)       /* Enable 64 bit mode */
 #define MSR_ISF                __MASK(MSR_ISF_LG)      /* Interrupt 64b mode valid on 630 */
 #define MSR_HV                 __MASK(MSR_HV_LG)       /* Hypervisor state */
+#else
+/* so tests for these bits fail on 32-bit */
+#define MSR_SF         0
+#define MSR_ISF                0
+#define MSR_HV         0
+#endif
+
 #define MSR_VEC                __MASK(MSR_VEC_LG)      /* Enable AltiVec */
 #define MSR_POW                __MASK(MSR_POW_LG)      /* Enable Power Management */
 #define MSR_WE         __MASK(MSR_WE_LG)       /* Wait State Enable */

diff --git a/include/asm-ppc64/sstep.h b/include/asm-powerpc/sstep.h
similarity index 85%
rename from include/asm-ppc64/sstep.h
rename to include/asm-powerpc/sstep.h
index 4a68db5..630a988 100644 (file)
--- a/include/asm-ppc64/sstep.h
+++ b/include/asm-powerpc/sstep.h
@@ -16,8 +16,10 @@ struct pt_regs;
  * we don't allow putting a breakpoint on an mtmsrd instruction.
  * Similarly we don't allow breakpoints on rfid instructions.
  * These macros tell us if an instruction is a mtmsrd or rfid.
+ * Note that IS_MTMSRD returns true for both an mtmsr (32-bit)
+ * and an mtmsrd (64-bit).
  */
-#define IS_MTMSRD(instr)       (((instr) & 0xfc0007fe) == 0x7c000164)
+#define IS_MTMSRD(instr)       (((instr) & 0xfc0007be) == 0x7c000124)
 #define IS_RFID(instr)         (((instr) & 0xfc0007fe) == 0x4c000024)
 
 /* Emulate instructions that cause a transfer of control. */