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powerpc: regain entire stack space 

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

There is also no risk anymore of corrupting task_cpu(p) with a
stack overflow so the patch removes the test.

When doing this, an explicit test for NULL stack pointer is
needed in validate_sp() as it is not anymore implicitely covered
by the sizeof(thread_info) gap.

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@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Christophe Leroy 2019-01-31 10:09:00 +00:00 committed by Michael Ellerman
parent ed1cd6deb0
commit a7916a1de5
8 changed files with 37 additions and 54 deletions
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10
arch/powerpc/include/asm/irq.h
View File

@ -48,16 +48,16 @@ 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];
#endif
/*
* 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];
void call_do_softirq(void *sp);
void call_do_irq(struct pt_regs *regs, void *sp);

3
arch/powerpc/include/asm/processor.h
View File

@ -270,8 +270,7 @@ 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 \

1
arch/powerpc/kernel/asm-offsets.c
View File

@ -92,7 +92,6 @@ int main(void)
DEFINE(SIGSEGV, SIGSEGV);
DEFINE(NMI_MASK, NMI_MASK);
#else
DEFINE(THREAD_INFO_GAP, _ALIGN_UP(sizeof(struct thread_info), 16));
OFFSET(KSP_LIMIT, thread_struct, ksp_limit);
#ifdef CONFIG_PPC_RTAS
OFFSET(RTAS_SP, thread_struct, rtas_sp);

14
arch/powerpc/kernel/entry_32.S
View File

@ -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

19
arch/powerpc/kernel/irq.c
View File

@ -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));
@ -686,17 +685,17 @@ 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;
#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 do_softirq_own_stack(void)
{
struct thread_info *irqtp;
void *irqtp;
irqtp = softirq_ctx[smp_processor_id()];
call_do_softirq(irqtp);

6
arch/powerpc/kernel/misc_32.S
View File

@ -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)

30
arch/powerpc/kernel/process.c
View File

@ -1691,8 +1691,7 @@ 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)end_of_stack(p);
#endif
#ifdef CONFIG_HAVE_HW_BREAKPOINT
p->thread.ptrace_bps[0] = NULL;
@ -1995,21 +1994,14 @@ static inline int valid_irq_stack(unsigned long sp, struct task_struct *p,
unsigned long stack_page;
unsigned long cpu = task_cpu(p);
/*
* Avoid crashing if the stack has overflowed and corrupted
* task_cpu(p), which is in the thread_info struct.
*/
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)
return 1;
stack_page = (unsigned long)hardirq_ctx[cpu];
if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;
stack_page = (unsigned long)softirq_ctx[cpu];
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)
return 1;
}
return 0;
}
@ -2018,8 +2010,10 @@ int validate_sp(unsigned long sp, struct task_struct *p,
{
unsigned long stack_page = (unsigned long)task_stack_page(p);
if (sp >= stack_page + sizeof(struct thread_struct)
&& sp <= stack_page + THREAD_SIZE - nbytes)
if (sp < THREAD_SIZE)
return 0;
if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;
return valid_irq_stack(sp, p, nbytes);

8
arch/powerpc/kernel/setup_64.c
View File

@ -716,19 +716,19 @@ 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);
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);
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);
paca_ptrs[i]->mc_emergency_sp = (void *)ti + THREAD_SIZE;
paca_ptrs[i]->mc_emergency_sp = ti + THREAD_SIZE;
#endif
}
}