(This is a VERY IMP change for low level interrupt/exception handling)
-----------------------------------------------------------------------
WHAT
-----------------------------------------------------------------------
* User 25 now saved in pt_regs->user_r25 (vs. tsk->thread_info.user_r25)
* This allows Low level interrupt code to unconditionally save r25
(vs. the prev version which would only do it for U->K transition).
Ofcourse for nested interrupts, only the pt_regs->user_r25 of
bottom-most frame is useful.
* simplifies the interrupt prologue/epilogue
* Needed for ARCv2 ISA code and done here to keep design similar with
ARCompact event handling
-----------------------------------------------------------------------
WHY
-------------------------------------------------------------------------
With CONFIG_ARC_CURR_IN_REG, r25 is used to cache "current" task pointer
in kernel mode. So when entering kernel mode from User Mode
- user r25 is specially safe-kept (it being a callee reg is NOT part of
pt_regs which are saved by default on each interrupt/trap/exception)
- r25 loaded with current task pointer.
Further, if interrupt was taken in kernel mode, this is skipped since we
know that r25 already has valid "current" pointer.
With 2 level of interrupts in ARCompact ISA, detecting this is difficult
but still possible, since we could be in kernel mode but r25 not already saved
(in fact the stack itself might not have been switched).
A. User mode
B. L1 IRQ taken
C. L2 IRQ taken (while on 1st line of L1 ISR)
So in #C, although in kernel mode, r25 not saved (infact SP not
switched at all)
Given that ARcompact has manual stack switching, we could use a bit of
trickey - The low level code would make sure that SP is only set to kernel
mode value at the very end (after saving r25). So a non kernel mode SP,
even if in kernel mode, meant r25 was NOT saved.
The same paradigm won't work in ARCv2 ISA since SP is auto-switched so
it's setting can't be delayed/constrained.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
+
+#ifdef CONFIG_ARC_CURR_IN_REG
+ ld r25, [sp, 12]
+#endif
.endm
/*--------------------------------------------------------------
.endm
/*--------------------------------------------------------------
+#define OFF_USER_R25_FROM_R24 (SZ_CALLEE_REGS + SZ_PT_REGS - 8)/4
/*--------------------------------------------------------------
* Collect User Mode callee regs as struct callee_regs - needed by
/*--------------------------------------------------------------
* Collect User Mode callee regs as struct callee_regs - needed by
#ifdef CONFIG_ARC_CURR_IN_REG
; Retrieve orig r25 and save it on stack
#ifdef CONFIG_ARC_CURR_IN_REG
; Retrieve orig r25 and save it on stack
- ld r12, [r25, TASK_THREAD + THREAD_USER_R25]
+ ld.as r12, [sp, OFF_USER_R25_FROM_R24]
st.a r12, [sp, -4]
#else
PUSH r25
st.a r12, [sp, -4]
#else
PUSH r25
#ifdef CONFIG_ARC_CURR_IN_REG
ld.ab r12, [sp, 4]
#ifdef CONFIG_ARC_CURR_IN_REG
ld.ab r12, [sp, 4]
- st r12, [r25, TASK_THREAD + THREAD_USER_R25]
+ st.as r12, [sp, OFF_USER_R25_FROM_R24]
add sp, sp, SZ_CALLEE_REGS
.endm
add sp, sp, SZ_CALLEE_REGS
.endm
-/*--------------------------------------------------------------
- * Restore User mode r25 saved in task_struct->thread.user_r25
- *-------------------------------------------------------------*/
-.macro RESTORE_USER_R25
- ld r25, [r25, TASK_THREAD + THREAD_USER_R25]
-.endm
-
/*-------------------------------------------------------------
* given a tsk struct, get to the base of it's kernel mode stack
* tsk->thread_info is really a PAGE, whose bottom hoists stack
/*-------------------------------------------------------------
* given a tsk struct, get to the base of it's kernel mode stack
* tsk->thread_info is really a PAGE, whose bottom hoists stack
-#ifdef CONFIG_ARC_CURR_IN_REG
-
- /* If current task pointer cached in r25, time to
- * -safekeep USER r25 in task->thread_struct->user_r25
- * -load r25 with current task ptr
- */
- st.as r25, [r9, (TASK_THREAD + THREAD_USER_R25)/4]
- mov r25, r9
-#endif
-
/* With current tsk in r9, get it's kernel mode stack base */
GET_TSK_STACK_BASE r9, r9
66:
/* With current tsk in r9, get it's kernel mode stack base */
GET_TSK_STACK_BASE r9, r9
66:
+#ifdef CONFIG_ARC_CURR_IN_REG
+ /*
+ * Treat r25 as scratch reg, save it on stack first
+ * Load it with current task pointer
+ */
+ st r25, [r9, -4]
+ GET_CURR_TASK_ON_CPU r25
+#endif
+
/* Save Pre Intr/Exception User SP on kernel stack */
/* Save Pre Intr/Exception User SP on kernel stack */
- st.a sp, [r9, -12] ; Make room for orig_r0 and orig_r8
+ st.a sp, [r9, -16] ; Make room for orig_r0, orig_r8, user_r25
/* CAUTION:
* SP should be set at the very end when we are done with everything
/* CAUTION:
* SP should be set at the very end when we are done with everything
RESTORE_R12_TO_R0
ld sp, [sp] /* restore original sp */
RESTORE_R12_TO_R0
ld sp, [sp] /* restore original sp */
- /* orig_r0 and orig_r8 skipped automatically */
+ /* orig_r0, orig_r8, user_r25 skipped automatically */
RESTORE_R12_TO_R0
ld sp, [sp] /* restore original sp */
RESTORE_R12_TO_R0
ld sp, [sp] /* restore original sp */
- /* orig_r0 and orig_r8 skipped automatically */
+ /* orig_r0, orig_r8, user_r25 skipped automatically */
.endm
.macro RESTORE_ALL_INT2
.endm
.macro RESTORE_ALL_INT2
RESTORE_R12_TO_R0
ld sp, [sp] /* restore original sp */
RESTORE_R12_TO_R0
ld sp, [sp] /* restore original sp */
- /* orig_r0 and orig_r8 skipped automatically */
+ /* orig_r0, orig_r8, user_r25 skipped automatically */
unsigned long callee_reg; /* pointer to callee regs */
unsigned long fault_address; /* dbls as brkpt holder as well */
unsigned long cause_code; /* Exception Cause Code (ECR) */
unsigned long callee_reg; /* pointer to callee regs */
unsigned long fault_address; /* dbls as brkpt holder as well */
unsigned long cause_code; /* Exception Cause Code (ECR) */
-#ifdef CONFIG_ARC_CURR_IN_REG
- unsigned long user_r25;
-#endif
#ifdef CONFIG_ARC_FPU_SAVE_RESTORE
struct arc_fpu fpu;
#endif
#ifdef CONFIG_ARC_FPU_SAVE_RESTORE
struct arc_fpu fpu;
#endif
#endif
long orig_r8_word;
};
#endif
long orig_r8_word;
};
};
/* Callee saved registers - need to be saved only when you are scheduled out */
};
/* Callee saved registers - need to be saved only when you are scheduled out */
DEFINE(THREAD_KSP, offsetof(struct thread_struct, ksp));
DEFINE(THREAD_CALLEE_REG, offsetof(struct thread_struct, callee_reg));
DEFINE(THREAD_KSP, offsetof(struct thread_struct, ksp));
DEFINE(THREAD_CALLEE_REG, offsetof(struct thread_struct, callee_reg));
-#ifdef CONFIG_ARC_CURR_IN_REG
- DEFINE(THREAD_USER_R25, offsetof(struct thread_struct, user_r25));
-#endif
DEFINE(THREAD_FAULT_ADDR,
offsetof(struct thread_struct, fault_address));
DEFINE(THREAD_FAULT_ADDR,
offsetof(struct thread_struct, fault_address));
DEFINE(PT_r7, offsetof(struct pt_regs, r7));
DEFINE(SZ_CALLEE_REGS, sizeof(struct callee_regs));
DEFINE(PT_r7, offsetof(struct pt_regs, r7));
DEFINE(SZ_CALLEE_REGS, sizeof(struct callee_regs));
+ DEFINE(SZ_PT_REGS, sizeof(struct pt_regs));
; XXX can this be optimised out
IRQ_DISABLE_SAVE r9, r10 ;@r10 has prisitine (pre-disable) copy
; XXX can this be optimised out
IRQ_DISABLE_SAVE r9, r10 ;@r10 has prisitine (pre-disable) copy
-#ifdef CONFIG_ARC_CURR_IN_REG
- ; Restore User R25
- ; Earlier this used to be only for returning to user mode
- ; However with 2 levels of IRQ this can also happen even if
- ; in kernel mode
- ld r9, [sp, PT_sp]
- brhs r9, VMALLOC_START, 8f
- RESTORE_USER_R25
-8:
-#endif
-
; Restore REG File. In case multiple Events outstanding,
; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None
; Note that we use realtime STATUS32 (not pt_regs->status32) to
; Restore REG File. In case multiple Events outstanding,
; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None
; Note that we use realtime STATUS32 (not pt_regs->status32) to
* | SP |
* | orig_r0 |
* | orig_r8 |
* | SP |
* | orig_r0 |
* | orig_r8 |
* ------------------ <===== END of PAGE
*/
int copy_thread(unsigned long clone_flags,
* ------------------ <===== END of PAGE
*/
int copy_thread(unsigned long clone_flags,