microblaze: Remove PER_CPU(KM) variable

There is a way howto remove Kernel Mode variable. It is easier
to parse UMS bit in MSR to find out if I come from kernel or user
space. Loading MSR content should be in one cycle and loading
PER_CPU variable depends on memory state.

Signed-off-by: Michal Simek <monstr@monstr.eu>

diff --git a/arch/microblaze/kernel/entry.S b/arch/microblaze/kernel/entry.S
index f5fe220954b0e636cbaec5d728f3bb406ad17160..9a98f70e4c304124153702d9274ebaec9bf596f3 100644 (file)
--- a/arch/microblaze/kernel/entry.S
+++ b/arch/microblaze/kernel/entry.S
@@ -275,9 +275,12 @@ C_ENTRY(_user_exception):
        addi    r14, r14, 4     /* return address is 4 byte after call */
        swi     r11, r0, TOPHYS(r0_ram + PTO + PT_R11); /* Save r11 */
 
-       lwi     r11, r0, TOPHYS(PER_CPU(KM));/* See if already in kernel mode.*/
-       beqi    r11, 1f;                /* Jump ahead if coming from user */
-/* Kernel-mode state save. */
+       mfs     r11, rmsr
+       nop
+       andi    r11, r11, MSR_UMS
+       bnei    r11, 1f
+
+/* Kernel-mode state save - kernel execve */
        lwi     r11, r0, TOPHYS(PER_CPU(ENTRY_SP)); /* Reload kernel stack-ptr*/
        tophys(r1,r11);
        swi     r11, r1, (PT_R1-PT_SIZE); /* Save original SP. */
@@ -307,8 +310,6 @@ C_ENTRY(_user_exception):
        swi     r0, r1, PTO+PT_MODE;                    /* Was in user-mode. */
        lwi     r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
        swi     r11, r1, PTO+PT_R1;             /* Store user SP.  */
-       addi    r11, r0, 1;
-       swi     r11, r0, TOPHYS(PER_CPU(KM));   /* Now we're in kernel-mode.  */
 2:     lwi     CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
        /* Save away the syscall number.  */
        swi     r12, r1, PTO+PT_R0;
@@ -423,7 +424,6 @@ C_ENTRY(ret_from_trap):
 
 /* Finally, return to user state.  */
 1:
-       swi     r0, r0, PER_CPU(KM);    /* Now officially in user state. */
        swi     CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE); /* save current */
        VM_OFF;
        tophys(r1,r1);
@@ -511,8 +511,10 @@ C_ENTRY(sys_rt_sigreturn_wrapper):
        enable_irq;                                                     \
        set_ee;                                                         \
        /* See if already in kernel mode.*/                             \
-       lwi     r11, r0, TOPHYS(PER_CPU(KM));                           \
-       beqi    r11, 1f;                /* Jump ahead if coming from user */\
+       mfs     r11, rmsr;                                              \
+       nop;                                                            \
+       andi    r11, r11, MSR_UMS;                                      \
+       bnei    r11, 1f;                                                \
        /* Kernel-mode state save.  */                                  \
        /* Reload kernel stack-ptr. */                                  \
        lwi     r11, r0, TOPHYS(PER_CPU(ENTRY_SP));                     \
@@ -544,8 +546,6 @@ C_ENTRY(sys_rt_sigreturn_wrapper):
        swi     r0, r1, PTO+PT_MODE; /* Was in user-mode.  */           \
        lwi     r11, r0, TOPHYS(PER_CPU(ENTRY_SP));                     \
        swi     r11, r1, PTO+PT_R1; /* Store user SP.  */               \
-       addi    r11, r0, 1;                                             \
-       swi     r11, r0, TOPHYS(PER_CPU(KM)); /* Now we're in kernel-mode.*/\
 2:     lwi     CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));        \
        /* Save away the syscall number.  */                            \
        swi     r0, r1, PTO+PT_R0;                                      \
@@ -686,7 +686,7 @@ C_ENTRY(ret_from_exc):
        add     r6, r0, r0;             /* Arg 2: sigset_t *oldset */
 
 /* Finally, return to user state.  */
-1:     swi     r0, r0, PER_CPU(KM);    /* Now officially in user state. */
+1:
        swi     CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE); /* save current */
        VM_OFF;
        tophys(r1,r1);
@@ -724,8 +724,10 @@ C_ENTRY(_interrupt):
        swi     r1, r0, TOPHYS(PER_CPU(ENTRY_SP))
        swi     r11, r0, TOPHYS(PER_CPU(R11_SAVE));
        /* MS: See if already in kernel mode. */
-       lwi     r11, r0, TOPHYS(PER_CPU(KM));
-       beqi    r11, 1f; /* MS: Jump ahead if coming from user */
+       mfs     r11, rmsr
+       nop
+       andi    r11, r11, MSR_UMS
+       bnei    r11, 1f
 
 /* Kernel-mode state save. */
        or      r11, r1, r0
@@ -761,10 +763,6 @@ C_ENTRY(_interrupt):
        swi     r0, r1, PTO + PT_MODE;
        lwi     r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
        swi     r11, r1, PTO+PT_R1;
-       /* setup kernel mode to KM */
-       addi    r11, r0, 1;
-       swi     r11, r0, TOPHYS(PER_CPU(KM));
-
 2:
        lwi     CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
        swi     r0, r1, PTO + PT_R0;
@@ -803,7 +801,6 @@ ret_from_irq:
 no_intr_resched:
     /* Disable interrupts, we are now committed to the state restore */
        disable_irq
-       swi     r0, r0, PER_CPU(KM); /* MS: Now officially in user state. */
        swi     CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE);
        VM_OFF;
        tophys(r1,r1);
@@ -858,8 +855,10 @@ C_ENTRY(_debug_exception):
        set_bip;        /*equalize initial state for all possible entries*/
        clear_eip;
        enable_irq;
-       lwi     r11, r0, TOPHYS(PER_CPU(KM));/* See if already in kernel mode.*/
-       beqi    r11, 1f;                /* Jump ahead if coming from user */
+       mfs     r11, rmsr
+       nop
+       andi    r11, r11, MSR_UMS
+       bnei    r11, 1f
        /* Kernel-mode state save.  */
        lwi     r11, r0, TOPHYS(PER_CPU(ENTRY_SP)); /* Reload kernel stack-ptr*/
        tophys(r1,r11);
@@ -887,8 +886,6 @@ C_ENTRY(_debug_exception):
        swi     r0, r1, PTO+PT_MODE; /* Was in user-mode.  */
        lwi     r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
        swi     r11, r1, PTO+PT_R1; /* Store user SP.  */
-       addi    r11, r0, 1;
-       swi     r11, r0, TOPHYS(PER_CPU(KM));   /* Now we're in kernel-mode.  */
 2:     lwi     CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
        /* Save away the syscall number.  */
        swi     r0, r1, PTO+PT_R0;
@@ -944,7 +941,7 @@ dbtrap_call:        rtbd    r11, 0;
 
 
 /* Finally, return to user state.  */
-1:     swi     r0, r0, PER_CPU(KM);    /* Now officially in user state. */
+1:
        swi     CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE); /* save current */
        VM_OFF;
        tophys(r1,r1);