powerpc/32: Handle bookE debugging in C in syscall entry/exit

The handling of SPRN_DBCR0 and other registers can easily
be done in C instead of ASM.

For that, create booke_load_dbcr0() and booke_restore_dbcr0().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1a7515f9258b27a9177de88491a8bb79b255ceb7.1612898425.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
index 5c285592d9b60bdb6252cc3919b6d1a188a9744d..aedfba29e43a5e0a39b52fa406eabf4dcda82e2e 100644 (file)
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -15,6 +15,18 @@ struct interrupt_state {
 #endif
 };
 
+static inline void booke_restore_dbcr0(void)
+{
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+       unsigned long dbcr0 = current->thread.debug.dbcr0;
+
+       if (IS_ENABLED(CONFIG_PPC32) && unlikely(dbcr0 & DBCR0_IDM)) {
+               mtspr(SPRN_DBSR, -1);
+               mtspr(SPRN_DBCR0, global_dbcr0[smp_processor_id()]);
+       }
+#endif
+}
+
 static inline void interrupt_enter_prepare(struct pt_regs *regs, struct interrupt_state *state)
 {
        /*

diff --git a/arch/powerpc/include/asm/reg_booke.h b/arch/powerpc/include/asm/reg_booke.h
index 262782f08fd48e23029313aecec175ef0f2e866b..17b8dcd9a40dedf137c1842bbbc6fe504e3e83d0 100644 (file)
--- a/arch/powerpc/include/asm/reg_booke.h
+++ b/arch/powerpc/include/asm/reg_booke.h
@@ -691,6 +691,9 @@
 #define mttmr(rn, v)   asm volatile(MTTMR(rn, %0) : \
                                     : "r" ((unsigned long)(v)) \
                                     : "memory")
+
+extern unsigned long global_dbcr0[];
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_POWERPC_REG_BOOKE_H__ */

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 9dd90be9f8a57662ad9cd5793c7d79d8853a4ec3..78c430b7f9d943316c8c538ee8ab164c3f32d995 100644 (file)
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -343,13 +343,6 @@ ret_from_syscall:
        addi    r4,r1,STACK_FRAME_OVERHEAD
        li      r5,0
        bl      syscall_exit_prepare
-#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
-       /* If the process has its own DBCR0 value, load it up.  The internal
-          debug mode bit tells us that dbcr0 should be loaded. */
-       lwz     r0,THREAD+THREAD_DBCR0(r2)
-       andis.  r10,r0,DBCR0_IDM@h
-       bnel-   load_dbcr0
-#endif
 #ifdef CONFIG_PPC_47x
        lis     r4,icache_44x_need_flush@ha
        lwz     r5,icache_44x_need_flush@l(r4)

diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index 1afad7bc3395f9630d506bd93790934293252856..5d4706c14572717493c563bd7919c2171fc394f2 100644 (file)
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -153,21 +153,6 @@
        SAVE_4GPRS(3, r11)
        SAVE_2GPRS(7, r11)
        addi    r2,r12,-THREAD
-#if defined(CONFIG_40x)
-       /* Check to see if the dbcr0 register is set up to debug.  Use the
-          internal debug mode bit to do this. */
-       lwz     r12,THREAD_DBCR0(r12)
-       andis.  r12,r12,DBCR0_IDM@h
-       beq+    3f
-       /* From user and task is ptraced - load up global dbcr0 */
-       li      r12,-1                  /* clear all pending debug events */
-       mtspr   SPRN_DBSR,r12
-       lis     r11,global_dbcr0@ha
-       addi    r11,r11,global_dbcr0@l
-       lwz     r12,0(r11)
-       mtspr   SPRN_DBCR0,r12
-3:
-#endif
        b       transfer_to_syscall             /* jump to handler */
 .endm
 

diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h
index 5f565232b99df112e2791c88367363e09ce4a028..47857795f50a64c4501406cb344cfb96bacba6dc 100644 (file)
--- a/arch/powerpc/kernel/head_booke.h
+++ b/arch/powerpc/kernel/head_booke.h
@@ -130,25 +130,6 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
        SAVE_2GPRS(7, r11)
 
        addi    r2,r10,-THREAD
-       /* Check to see if the dbcr0 register is set up to debug.  Use the
-          internal debug mode bit to do this. */
-       lwz     r12,THREAD_DBCR0(r10)
-       andis.  r12,r12,DBCR0_IDM@h
-       beq+    3f
-       /* From user and task is ptraced - load up global dbcr0 */
-       li      r12,-1                  /* clear all pending debug events */
-       mtspr   SPRN_DBSR,r12
-       lis     r11,global_dbcr0@ha
-       addi    r11,r11,global_dbcr0@l
-#ifdef CONFIG_SMP
-       lwz     r10, TASK_CPU(r2)
-       slwi    r10, r10, 2
-       add     r11, r11, r10
-#endif
-       lwz     r12,0(r11)
-       mtspr   SPRN_DBCR0,r12
-
-3:
        b       transfer_to_syscall     /* jump to handler */
 .endm
 

diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
index 75d657b63332459325bf9d34a48c948eead5bfcc..f93664ad4a5e25699bee63a0e656d8a826e2ac4a 100644 (file)
--- a/arch/powerpc/kernel/interrupt.c
+++ b/arch/powerpc/kernel/interrupt.c
@@ -73,6 +73,8 @@ notrace long system_call_exception(long r3, long r4, long r5,
                kuap_check_amr();
 #endif
 
+       booke_restore_dbcr0();
+
        account_cpu_user_entry();
 
        account_stolen_time();
@@ -204,6 +206,28 @@ static notrace inline bool prep_irq_for_enabled_exit(bool clear_ri, bool irqs_en
        return false;
 }
 
+static notrace void booke_load_dbcr0(void)
+{
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+       unsigned long dbcr0 = current->thread.debug.dbcr0;
+
+       if (likely(!(dbcr0 & DBCR0_IDM)))
+               return;
+
+       /*
+        * Check to see if the dbcr0 register is set up to debug.
+        * Use the internal debug mode bit to do this.
+        */
+       mtmsr(mfmsr() & ~MSR_DE);
+       if (IS_ENABLED(CONFIG_PPC32)) {
+               isync();
+               global_dbcr0[smp_processor_id()] = mfspr(SPRN_DBCR0);
+       }
+       mtspr(SPRN_DBCR0, dbcr0);
+       mtspr(SPRN_DBSR, -1);
+#endif
+}
+
 /*
  * This should be called after a syscall returns, with r3 the return value
  * from the syscall. If this function returns non-zero, the system call
@@ -317,6 +341,8 @@ again:
        local_paca->tm_scratch = regs->msr;
 #endif
 
+       booke_load_dbcr0();
+
        account_cpu_user_exit();
 
 #ifdef CONFIG_PPC_BOOK3S_64 /* BOOK3E and ppc32 not using this */
@@ -331,9 +357,6 @@ again:
 #ifndef CONFIG_PPC_BOOK3E_64 /* BOOK3E not yet using this */
 notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned long msr)
 {
-#ifdef CONFIG_PPC_BOOK3E
-       struct thread_struct *ts = &current->thread;
-#endif
        unsigned long *ti_flagsp = &current_thread_info()->flags;
        unsigned long ti_flags;
        unsigned long flags;
@@ -398,17 +421,7 @@ again:
                goto again;
        }
 
-#ifdef CONFIG_PPC_BOOK3E
-       if (unlikely(ts->debug.dbcr0 & DBCR0_IDM)) {
-               /*
-                * Check to see if the dbcr0 register is set up to debug.
-                * Use the internal debug mode bit to do this.
-                */
-               mtmsr(mfmsr() & ~MSR_DE);
-               mtspr(SPRN_DBCR0, ts->debug.dbcr0);
-               mtspr(SPRN_DBSR, -1);
-       }
-#endif
+       booke_load_dbcr0();
 
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
        local_paca->tm_scratch = regs->msr;