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 f5fe220..9a98f70 100644
--- a/arch/microblaze/kernel/entry.S
+++ b/arch/microblaze/kernel/entry.S
@@ -275,9 +275,12 @@
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 @@
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 @@
/* 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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
/* 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);