Commit 85218827 authored by Kumar Gala's avatar Kumar Gala Committed by Paul Mackerras

[POWERPC] Add IRQSTACKS support on ppc32

This makes it possible to use separate stacks for hard and soft IRQs
on 32-bit powerpc as well as on 64-bit.  The code for 32-bit is just
the 32-bit analog of the 64-bit code.

* Added allocation and initialization of the irq stacks.  We limit the
  stacks to be in lowmem for ppc32.
* Implemented ppc32 versions of call_do_softirq() and call_handle_irq()
  to switch the stack pointers
* Reworked how we do stack overflow detection.  We now keep around the
  limit of the stack in the thread_struct and compare against the limit
  to see if we've overflowed.  We can now use this on ppc64 if desired.

[ paulus@samba.org: Fixed bug on 6xx where we need to reload r9 with the
  thread_info pointer. ]
Signed-off-by: default avatarKumar Gala <galak@kernel.crashing.org>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent dd18434f
......@@ -118,7 +118,6 @@ config XMON_DISASSEMBLY
config IRQSTACKS
bool "Use separate kernel stacks when processing interrupts"
depends on PPC64
help
If you say Y here the kernel will use separate kernel stacks
for handling hard and soft interrupts. This can help avoid
......
......@@ -67,6 +67,7 @@ int main(void)
#endif /* CONFIG_PPC64 */
DEFINE(KSP, offsetof(struct thread_struct, ksp));
DEFINE(KSP_LIMIT, offsetof(struct thread_struct, ksp_limit));
DEFINE(PT_REGS, offsetof(struct thread_struct, regs));
DEFINE(THREAD_FPEXC_MODE, offsetof(struct thread_struct, fpexc_mode));
DEFINE(THREAD_FPR0, offsetof(struct thread_struct, fpr[0]));
......
......@@ -137,11 +137,12 @@ transfer_to_handler:
2: /* if from kernel, check interrupted DOZE/NAP mode and
* check for stack overflow
*/
lwz r9,THREAD_INFO-THREAD(r12)
cmplw r1,r9 /* if r1 <= current->thread_info */
lwz r9,KSP_LIMIT(r12)
cmplw r1,r9 /* if r1 <= ksp_limit */
ble- stack_ovf /* then the kernel stack overflowed */
5:
#ifdef CONFIG_6xx
rlwinm r9,r1,0,0,31-THREAD_SHIFT
tophys(r9,r9) /* check local flags */
lwz r12,TI_LOCAL_FLAGS(r9)
mtcrf 0x01,r12
......
......@@ -307,6 +307,7 @@ void do_IRQ(struct pt_regs *regs)
if (curtp != irqtp) {
struct irq_desc *desc = irq_desc + irq;
void *handler = desc->handle_irq;
unsigned long saved_sp_limit = current->thread.ksp_limit;
if (handler == NULL)
handler = &__do_IRQ;
irqtp->task = curtp->task;
......@@ -319,7 +320,10 @@ void do_IRQ(struct pt_regs *regs)
(irqtp->preempt_count & ~SOFTIRQ_MASK) |
(curtp->preempt_count & SOFTIRQ_MASK);
current->thread.ksp_limit = (unsigned long)irqtp +
_ALIGN_UP(sizeof(struct thread_info), 16);
call_handle_irq(irq, desc, irqtp, handler);
current->thread.ksp_limit = saved_sp_limit;
irqtp->task = NULL;
......@@ -352,9 +356,7 @@ void __init init_IRQ(void)
{
if (ppc_md.init_IRQ)
ppc_md.init_IRQ();
#ifdef CONFIG_PPC64
irq_ctx_init();
#endif
}
......@@ -383,11 +385,15 @@ void irq_ctx_init(void)
static inline void do_softirq_onstack(void)
{
struct thread_info *curtp, *irqtp;
unsigned long saved_sp_limit = current->thread.ksp_limit;
curtp = current_thread_info();
irqtp = softirq_ctx[smp_processor_id()];
irqtp->task = curtp->task;
current->thread.ksp_limit = (unsigned long)irqtp +
_ALIGN_UP(sizeof(struct thread_info), 16);
call_do_softirq(irqtp);
current->thread.ksp_limit = saved_sp_limit;
irqtp->task = NULL;
}
......
......@@ -32,6 +32,31 @@
.text
#ifdef CONFIG_IRQSTACKS
_GLOBAL(call_do_softirq)
mflr r0
stw r0,4(r1)
stwu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r3)
mr r1,r3
bl __do_softirq
lwz r1,0(r1)
lwz r0,4(r1)
mtlr r0
blr
_GLOBAL(call_handle_irq)
mflr r0
stw r0,4(r1)
mtctr r6
stwu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r5)
mr r1,r5
bctrl
lwz r1,0(r1)
lwz r0,4(r1)
mtlr r0
blr
#endif /* CONFIG_IRQSTACKS */
/*
* This returns the high 64 bits of the product of two 64-bit numbers.
*/
......
......@@ -589,6 +589,8 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
kregs = (struct pt_regs *) sp;
sp -= STACK_FRAME_OVERHEAD;
p->thread.ksp = sp;
p->thread.ksp_limit = (unsigned long)task_stack_page(p) +
_ALIGN_UP(sizeof(struct thread_info), 16);
#ifdef CONFIG_PPC64
if (cpu_has_feature(CPU_FTR_SLB)) {
......
......@@ -16,6 +16,7 @@
#include <linux/root_dev.h>
#include <linux/cpu.h>
#include <linux/console.h>
#include <linux/lmb.h>
#include <asm/io.h>
#include <asm/prom.h>
......@@ -229,6 +230,24 @@ int __init ppc_init(void)
arch_initcall(ppc_init);
#ifdef CONFIG_IRQSTACKS
static void __init irqstack_early_init(void)
{
unsigned int i;
/* interrupt stacks must be in lowmem, we get that for free on ppc32
* as the lmb is limited to lowmem by LMB_REAL_LIMIT */
for_each_possible_cpu(i) {
softirq_ctx[i] = (struct thread_info *)
__va(lmb_alloc(THREAD_SIZE, THREAD_SIZE));
hardirq_ctx[i] = (struct thread_info *)
__va(lmb_alloc(THREAD_SIZE, THREAD_SIZE));
}
}
#else
#define irqstack_early_init()
#endif
/* Warning, IO base is not yet inited */
void __init setup_arch(char **cmdline_p)
{
......@@ -286,6 +305,8 @@ void __init setup_arch(char **cmdline_p)
init_mm.end_data = (unsigned long) _edata;
init_mm.brk = klimit;
irqstack_early_init();
/* set up the bootmem stuff with available memory */
do_init_bootmem();
if ( ppc_md.progress ) ppc_md.progress("setup_arch: bootmem", 0x3eab);
......
......@@ -138,6 +138,8 @@ typedef struct {
struct thread_struct {
unsigned long ksp; /* Kernel stack pointer */
unsigned long ksp_limit; /* if ksp <= ksp_limit stack overflow */
#ifdef CONFIG_PPC64
unsigned long ksp_vsid;
#endif
......@@ -182,11 +184,14 @@ struct thread_struct {
#define ARCH_MIN_TASKALIGN 16
#define INIT_SP (sizeof(init_stack) + (unsigned long) &init_stack)
#define INIT_SP_LIMIT \
(_ALIGN_UP(sizeof(init_thread_info), 16) + (unsigned long) &init_stack)
#ifdef CONFIG_PPC32
#define INIT_THREAD { \
.ksp = INIT_SP, \
.ksp_limit = INIT_SP_LIMIT, \
.fs = KERNEL_DS, \
.pgdir = swapper_pg_dir, \
.fpexc_mode = MSR_FE0 | MSR_FE1, \
......@@ -194,6 +199,7 @@ struct thread_struct {
#else
#define INIT_THREAD { \
.ksp = INIT_SP, \
.ksp_limit = INIT_SP_LIMIT, \
.regs = (struct pt_regs *)INIT_SP - 1, /* XXX bogus, I think */ \
.fs = KERNEL_DS, \
.fpr = {0}, \
......
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