sh: Wire up division and address error exceptions on SH-2A.

SH-2A has special division hardware as opposed to a full-fledged FPU,
wire up the exception handlers for this.

Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 79 insertions, 9 deletions

diff --git a/arch/sh/kernel/traps.c b/arch/sh/kernel/traps.c
index 53dfa55f3156..1edec2709efe 100644
--- a/arch/sh/kernel/traps.c
+++ b/arch/sh/kernel/traps.c
@@ -33,8 +33,13 @@
 #endif
 
 #ifdef CONFIG_CPU_SH2
-#define TRAP_RESERVED_INST      4
-#define TRAP_ILLEGAL_SLOT_INST  6
+# define TRAP_RESERVED_INST     4
+# define TRAP_ILLEGAL_SLOT_INST 6
+# define TRAP_ADDRESS_ERROR     9
+# ifdef CONFIG_CPU_SH2A
+#  define TRAP_DIVZERO_ERROR    17
+#  define TRAP_DIVOVF_ERROR     18
+# endif
 #else
 #define TRAP_RESERVED_INST      12
 #define TRAP_ILLEGAL_SLOT_INST  13
@@ -479,6 +484,14 @@ static int handle_unaligned_access(u16 instruction, struct pt_regs *regs)
         return ret;
 }
 
+#ifdef CONFIG_CPU_HAS_SR_RB
+#define lookup_exception_vector(x)      \
+        __asm__ __volatile__ ("stc r2_bank, %0\n\t" : "=r" ((x)))
+#else
+#define lookup_exception_vector(x)      \
+        __asm__ __volatile__ ("mov r4, %0\n\t" : "=r" ((x)))
+#endif
+
 /*
  * Handle various address error exceptions
  */
@@ -486,24 +499,37 @@ asmlinkage void do_address_error(struct pt_regs *regs,
                                  unsigned long writeaccess,
                                  unsigned long address)
 {
-        unsigned long error_code;
+        unsigned long error_code = 0;
         mm_segment_t oldfs;
         u16 instruction;
         int tmp;
 
-        asm volatile("stc       r2_bank,%0": "=r" (error_code));
+        /* Intentional ifdef */
+#ifdef CONFIG_CPU_HAS_SR_RB
+        lookup_exception_vector(error_code);
+#endif
 
         oldfs = get_fs();
 
         if (user_mode(regs)) {
                 local_irq_enable();
                 current->thread.error_code = error_code;
+#ifdef CONFIG_CPU_SH2
+                /*
+                 * On the SH-2, we only have a single vector for address
+                 * errors, there's no differentiating between a load error
+                 * and a store error.
+                 */
+                current->thread.trap_no = 9;
+#else
                 current->thread.trap_no = (writeaccess) ? 8 : 7;
+#endif
 
                 /* bad PC is not something we can fix */
                 if (regs->pc & 1)
                         goto uspace_segv;
 
+#ifndef CONFIG_CPU_SH2A
                 set_fs(USER_DS);
                 if (copy_from_user(&instruction, (u16 *)(regs->pc), 2)) {
                         /* Argh. Fault on the instruction itself.
@@ -518,6 +544,7 @@ asmlinkage void do_address_error(struct pt_regs *regs,
 
                 if (tmp==0)
                         return; /* sorted */
+#endif
 
         uspace_segv:
                 printk(KERN_NOTICE "Killing process \"%s\" due to unaligned access\n", current->comm);
@@ -526,6 +553,7 @@ asmlinkage void do_address_error(struct pt_regs *regs,
                 if (regs->pc & 1)
                         die("unaligned program counter", regs, error_code);
 
+#ifndef CONFIG_CPU_SH2A
                 set_fs(KERNEL_DS);
                 if (copy_from_user(&instruction, (u16 *)(regs->pc), 2)) {
                         /* Argh. Fault on the instruction itself.
@@ -537,6 +565,10 @@ asmlinkage void do_address_error(struct pt_regs *regs,
 
                 handle_unaligned_access(instruction, regs);
                 set_fs(oldfs);
+#else
+                printk(KERN_NOTICE "Killing process \"%s\" due to unaligned access\n", current->comm);
+                force_sig(SIGSEGV, current);
+#endif
         }
 }
 
@@ -569,6 +601,29 @@ int is_dsp_inst(struct pt_regs *regs)
 #define is_dsp_inst(regs)       (0)
 #endif /* CONFIG_SH_DSP */
 
+#ifdef CONFIG_CPU_SH2A
+asmlinkage void do_divide_error(unsigned long r4, unsigned long r5,
+                                unsigned long r6, unsigned long r7,
+                                struct pt_regs regs)
+{
+        siginfo_t info;
+
+        current->thread.trap_no = r4;
+        current->thread.error_code = 0;
+
+        switch (r4) {
+        case TRAP_DIVZERO_ERROR:
+                info.si_code = FPE_INTDIV;
+                break;
+        case TRAP_DIVOVF_ERROR:
+                info.si_code = FPE_INTOVF;
+                break;
+        }
+
+        force_sig_info(SIGFPE, &info, current);
+}
+#endif
+
 /* arch/sh/kernel/cpu/sh4/fpu.c */
 extern int do_fpu_inst(unsigned short, struct pt_regs *);
 extern asmlinkage void do_fpu_state_restore(unsigned long r4, unsigned long r5,
@@ -582,7 +637,7 @@ asmlinkage void do_reserved_inst(unsigned long r4, unsigned long r5,
         struct task_struct *tsk = current;
 
 #ifdef CONFIG_SH_FPU_EMU
-        unsigned short inst;
+        unsigned short inst = 0;
         int err;
 
         get_user(inst, (unsigned short*)regs.pc);
@@ -604,7 +659,8 @@ asmlinkage void do_reserved_inst(unsigned long r4, unsigned long r5,
         }
 #endif
 
-        asm volatile("stc       r2_bank, %0": "=r" (error_code));
+        lookup_exception_vector(error_code);
+
         local_irq_enable();
         tsk->thread.error_code = error_code;
         tsk->thread.trap_no = TRAP_RESERVED_INST;
@@ -663,7 +719,7 @@ asmlinkage void do_illegal_slot_inst(unsigned long r4, unsigned long r5,
         unsigned long error_code;
         struct task_struct *tsk = current;
 #ifdef CONFIG_SH_FPU_EMU
-        unsigned short inst;
+        unsigned short inst = 0;
 
         get_user(inst, (unsigned short *)regs.pc + 1);
         if (!do_fpu_inst(inst, &regs)) {
@@ -675,7 +731,8 @@ asmlinkage void do_illegal_slot_inst(unsigned long r4, unsigned long r5,
         /* not a FPU inst. */
 #endif
 
-        asm volatile("stc       r2_bank, %0": "=r" (error_code));
+        lookup_exception_vector(error_code);
+
         local_irq_enable();
         tsk->thread.error_code = error_code;
         tsk->thread.trap_no = TRAP_RESERVED_INST;
@@ -689,7 +746,8 @@ asmlinkage void do_exception_error(unsigned long r4, unsigned long r5,
                                    struct pt_regs regs)
 {
         long ex;
-        asm volatile("stc       r2_bank, %0" : "=r" (ex));
+
+        lookup_exception_vector(ex);
         die_if_kernel("exception", &regs, ex);
 }
 
@@ -741,6 +799,10 @@ void *set_exception_table_vec(unsigned int vec, void *handler)
         return old_handler;
 }
 
+extern asmlinkage void address_error_handler(unsigned long r4, unsigned long r5,
+                                             unsigned long r6, unsigned long r7,
+                                             struct pt_regs regs);
+
 void __init trap_init(void)
 {
         set_exception_table_vec(TRAP_RESERVED_INST, do_reserved_inst);
@@ -759,6 +821,14 @@ void __init trap_init(void)
         set_exception_table_evt(0x800, do_fpu_state_restore);
         set_exception_table_evt(0x820, do_fpu_state_restore);
 #endif
+
+#ifdef CONFIG_CPU_SH2
+        set_exception_table_vec(TRAP_ADDRESS_ERROR, address_error_handler);
+#endif
+#ifdef CONFIG_CPU_SH2A
+        set_exception_table_vec(TRAP_DIVZERO_ERROR, do_divide_error);
+        set_exception_table_vec(TRAP_DIVOVF_ERROR, do_divide_error);
+#endif
                 
         /* Setup VBR for boot cpu */
         per_cpu_trap_init();