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

Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
---
v5: New
---
 arch/powerpc/include/asm/reg_booke.h |  3 +++
 arch/powerpc/kernel/entry_32.S       |  7 -------
 arch/powerpc/kernel/head_32.h        | 15 --------------
 arch/powerpc/kernel/head_booke.h     | 19 ------------------
 arch/powerpc/kernel/interrupt.c      | 29 +++++++++++++++++++++++++++-
 5 files changed, 31 insertions(+), 42 deletions(-)

diff --git a/arch/powerpc/include/asm/reg_booke.h 
b/arch/powerpc/include/asm/reg_booke.h
index 262782f08fd4..17b8dcd9a40d 100644
--- 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 a574201b0eb6..8dea4d3b1d06 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -342,13 +342,6 @@ transfer_to_syscall:
 ret_from_syscall:
        addi    r4,r1,STACK_FRAME_OVERHEAD
        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 5001c6ecc3ec..961b1ce3b6bf 100644
--- 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 5f565232b99d..47857795f50a 100644
--- 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 c89a8eac3e24..6111acf61373 100644
--- a/arch/powerpc/kernel/interrupt.c
+++ b/arch/powerpc/kernel/interrupt.c
@@ -76,6 +76,13 @@ notrace long system_call_exception(long r3, long r4, long r5,
                kuap_check_amr();
 #endif
 
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+       if (IS_ENABLED(CONFIG_PPC32) && unlikely(current->thread.debug.dbcr0 & 
DBCR0_IDM)) {
+               mtspr(SPRN_DBSR, -1);
+               mtspr(SPRN_DBCR0, global_dbcr0[smp_processor_id()]);
+       }
+#endif
+
        account_cpu_user_entry();
 
        account_stolen_time();
@@ -324,6 +331,22 @@ notrace unsigned long syscall_exit_prepare(unsigned long 
r3,
        local_paca->tm_scratch = regs->msr;
 #endif
 
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+       if (unlikely(current->thread.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);
+               if (IS_ENABLED(CONFIG_PPC32)) {
+                       isync();
+                       global_dbcr0[smp_processor_id()] = mfspr(SPRN_DBCR0);
+               }
+               mtspr(SPRN_DBCR0, current->thread.debug.dbcr0);
+               mtspr(SPRN_DBSR, -1);
+       }
+#endif
+
        account_cpu_user_exit();
 
 #ifdef CONFIG_PPC_BOOK3S_64 /* BOOK3E and ppc32 not using this */
@@ -401,13 +424,17 @@ notrace unsigned long interrupt_exit_user_prepare(struct 
pt_regs *regs, unsigned
                goto again;
        }
 
-#ifdef CONFIG_PPC_BOOK3E
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
        if (unlikely(current->thread.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);
+               if (IS_ENABLED(CONFIG_PPC32)) {
+                       isync();
+                       global_dbcr0[smp_processor_id()] = mfspr(SPRN_DBCR0);
+               }
                mtspr(SPRN_DBCR0, current->thread.debug.dbcr0);
                mtspr(SPRN_DBSR, -1);
        }
-- 
2.25.0

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