[PATCH v6 5/9] powerpc: regain entire stack space

From: Christophe Leroy
Date: Mon Oct 08 2018 - 05:16:40 EST

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thread_info is not anymore in the stack, so the entire stack
can now be used.

In the meantime, with the previous patch all pointers to the stacks
are not anymore pointers to thread_info so this patch changes them
to void*

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
arch/powerpc/include/asm/irq.h | 10 +++++-----
arch/powerpc/include/asm/processor.h | 3 +--
arch/powerpc/kernel/asm-offsets.c | 1 -
arch/powerpc/kernel/entry_32.S | 14 ++++----------
arch/powerpc/kernel/irq.c | 19 +++++++++----------
arch/powerpc/kernel/misc_32.S | 6 ++----
arch/powerpc/kernel/process.c | 9 +++------
arch/powerpc/kernel/setup_64.c | 8 ++++----
8 files changed, 28 insertions(+), 42 deletions(-)

diff --git a/arch/powerpc/include/asm/irq.h b/arch/powerpc/include/asm/irq.h
index 2efbae8d93be..966ddd4d2414 100644
--- a/arch/powerpc/include/asm/irq.h
+++ b/arch/powerpc/include/asm/irq.h
@@ -48,9 +48,9 @@ struct pt_regs;
* Per-cpu stacks for handling critical, debug and machine check
* level interrupts.
*/
-extern struct thread_info *critirq_ctx[NR_CPUS];
-extern struct thread_info *dbgirq_ctx[NR_CPUS];
-extern struct thread_info *mcheckirq_ctx[NR_CPUS];
+extern void *critirq_ctx[NR_CPUS];
+extern void *dbgirq_ctx[NR_CPUS];
+extern void *mcheckirq_ctx[NR_CPUS];
extern void exc_lvl_ctx_init(void);
#else
#define exc_lvl_ctx_init()
@@ -59,8 +59,8 @@ extern void exc_lvl_ctx_init(void);
/*
* Per-cpu stacks for handling hard and soft interrupts.
*/
-extern struct thread_info *hardirq_ctx[NR_CPUS];
-extern struct thread_info *softirq_ctx[NR_CPUS];
+extern void *hardirq_ctx[NR_CPUS];
+extern void *softirq_ctx[NR_CPUS];

extern void irq_ctx_init(void);
void call_do_softirq(void *sp);
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index b225c7f7c5a4..e763342265a2 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -331,8 +331,7 @@ 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(struct thread_info), 16) + (unsigned long)&init_stack)
+#define INIT_SP_LIMIT ((unsigned long)&init_stack)

#ifdef CONFIG_SPE
#define SPEFSCR_INIT \
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 833d189df04c..768ce602d624 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -93,7 +93,6 @@ int main(void)
DEFINE(NMI_MASK, NMI_MASK);
OFFSET(TASKTHREADPPR, task_struct, thread.ppr);
#else
- DEFINE(THREAD_INFO_GAP, _ALIGN_UP(sizeof(struct thread_info), 16));
OFFSET(KSP_LIMIT, thread_struct, ksp_limit);
#endif /* CONFIG_PPC64 */
OFFSET(TASK_STACK, task_struct, stack);
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index fa7a69ffb37a..bd3b146e18a3 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -97,14 +97,11 @@ crit_transfer_to_handler:
mfspr r0,SPRN_SRR1
stw r0,_SRR1(r11)

- /* set the stack limit to the current stack
- * and set the limit to protect the thread_info
- * struct
- */
+ /* set the stack limit to the current stack */
mfspr r8,SPRN_SPRG_THREAD
lwz r0,KSP_LIMIT(r8)
stw r0,SAVED_KSP_LIMIT(r11)
- rlwimi r0,r1,0,0,(31-THREAD_SHIFT)
+ rlwinm r0,r1,0,0,(31 - THREAD_SHIFT)
stw r0,KSP_LIMIT(r8)
/* fall through */
#endif
@@ -121,14 +118,11 @@ crit_transfer_to_handler:
mfspr r0,SPRN_SRR1
stw r0,crit_srr1@l(0)

- /* set the stack limit to the current stack
- * and set the limit to protect the thread_info
- * struct
- */
+ /* set the stack limit to the current stack */
mfspr r8,SPRN_SPRG_THREAD
lwz r0,KSP_LIMIT(r8)
stw r0,saved_ksp_limit@l(0)
- rlwimi r0,r1,0,0,(31-THREAD_SHIFT)
+ rlwinm r0,r1,0,0,(31 - THREAD_SHIFT)
stw r0,KSP_LIMIT(r8)
/* fall through */
#endif
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 3fdb6b6973cf..62cfccf4af89 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -618,9 +618,8 @@ static inline void check_stack_overflow(void)
sp = current_stack_pointer() & (THREAD_SIZE-1);

/* check for stack overflow: is there less than 2KB free? */
- if (unlikely(sp < (sizeof(struct thread_info) + 2048))) {
- pr_err("do_IRQ: stack overflow: %ld\n",
- sp - sizeof(struct thread_info));
+ if (unlikely(sp < 2048)) {
+ pr_err("do_IRQ: stack overflow: %ld\n", sp);
dump_stack();
}
#endif
@@ -660,7 +659,7 @@ void __do_irq(struct pt_regs *regs)
void do_IRQ(struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
- struct thread_info *curtp, *irqtp, *sirqtp;
+ void *curtp, *irqtp, *sirqtp;

/* Switch to the irq stack to handle this */
curtp = (void *)(current_stack_pointer() & ~(THREAD_SIZE - 1));
@@ -690,9 +689,9 @@ void __init init_IRQ(void)
}

#if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
-struct thread_info *critirq_ctx[NR_CPUS] __read_mostly;
-struct thread_info *dbgirq_ctx[NR_CPUS] __read_mostly;
-struct thread_info *mcheckirq_ctx[NR_CPUS] __read_mostly;
+void *critirq_ctx[NR_CPUS] __read_mostly;
+void *dbgirq_ctx[NR_CPUS] __read_mostly;
+void *mcheckirq_ctx[NR_CPUS] __read_mostly;

void exc_lvl_ctx_init(void)
{
@@ -718,8 +717,8 @@ void exc_lvl_ctx_init(void)
}
#endif

-struct thread_info *softirq_ctx[NR_CPUS] __read_mostly;
-struct thread_info *hardirq_ctx[NR_CPUS] __read_mostly;
+void *softirq_ctx[NR_CPUS] __read_mostly;
+void *hardirq_ctx[NR_CPUS] __read_mostly;

void irq_ctx_init(void)
{
@@ -733,7 +732,7 @@ void irq_ctx_init(void)

void do_softirq_own_stack(void)
{
- struct thread_info *irqtp;
+ void *irqtp;

irqtp = softirq_ctx[smp_processor_id()];
call_do_softirq(irqtp);
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index 32762f4c3458..a3663ad62f16 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -46,11 +46,10 @@ _GLOBAL(call_do_softirq)
mflr r0
stw r0,4(r1)
lwz r10,THREAD+KSP_LIMIT(r2)
- addi r11,r3,THREAD_INFO_GAP
+ stw r3, THREAD+KSP_LIMIT(r2)
stwu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r3)
mr r1,r3
stw r10,8(r1)
- stw r11,THREAD+KSP_LIMIT(r2)
bl __do_softirq
lwz r10,8(r1)
lwz r1,0(r1)
@@ -66,11 +65,10 @@ _GLOBAL(call_do_irq)
mflr r0
stw r0,4(r1)
lwz r10,THREAD+KSP_LIMIT(r2)
- addi r11,r4,THREAD_INFO_GAP
+ stw r4, THREAD+KSP_LIMIT(r2)
stwu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r4)
mr r1,r4
stw r10,8(r1)
- stw r11,THREAD+KSP_LIMIT(r2)
bl __do_irq
lwz r10,8(r1)
lwz r1,0(r1)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index a12307ebb7ef..afe76f7f316c 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1689,8 +1689,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
sp -= STACK_FRAME_OVERHEAD;
p->thread.ksp = sp;
#ifdef CONFIG_PPC32
- p->thread.ksp_limit = (unsigned long)task_stack_page(p) +
- _ALIGN_UP(sizeof(struct thread_info), 16);
+ p->thread.ksp_limit = (unsigned long)task_stack_page(p);
#endif
#ifdef CONFIG_HAVE_HW_BREAKPOINT
p->thread.ptrace_bps[0] = NULL;
@@ -1992,13 +1991,11 @@ static inline int valid_irq_stack(unsigned long sp, struct task_struct *p,
*/
if (cpu < NR_CPUS && cpu_possible(cpu)) {
stack_page = (unsigned long) hardirq_ctx[cpu];
- if (sp >= stack_page + sizeof(struct thread_struct)
- && sp <= stack_page + THREAD_SIZE - nbytes)
+ if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;

stack_page = (unsigned long) softirq_ctx[cpu];
- if (sp >= stack_page + sizeof(struct thread_struct)
- && sp <= stack_page + THREAD_SIZE - nbytes)
+ if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;
}
return 0;
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 2d682f3e31c6..6792e9c90689 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -717,22 +717,22 @@ void __init emergency_stack_init(void)
limit = min(ppc64_bolted_size(), ppc64_rma_size);

for_each_possible_cpu(i) {
- struct thread_info *ti;
+ void *ti;

ti = alloc_stack(limit, i);
memset(ti, 0, THREAD_SIZE);
- paca_ptrs[i]->emergency_sp = (void *)ti + THREAD_SIZE;
+ paca_ptrs[i]->emergency_sp = ti + THREAD_SIZE;

#ifdef CONFIG_PPC_BOOK3S_64
/* emergency stack for NMI exception handling. */
ti = alloc_stack(limit, i);
memset(ti, 0, THREAD_SIZE);
- paca_ptrs[i]->nmi_emergency_sp = (void *)ti + THREAD_SIZE;
+ paca_ptrs[i]->nmi_emergency_sp = ti + THREAD_SIZE;

/* emergency stack for machine check exception handling. */
ti = alloc_stack(limit, i);
memset(ti, 0, THREAD_SIZE);
- paca_ptrs[i]->mc_emergency_sp = (void *)ti + THREAD_SIZE;
+ paca_ptrs[i]->mc_emergency_sp = ti + THREAD_SIZE;
#endif
}
}
--
2.13.3

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