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powerpc: Activate CONFIG_THREAD_INFO_IN_TASK

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This patch activates CONFIG_THREAD_INFO_IN_TASK which
moves the thread_info into task_struct.

Moving thread_info into task_struct has the following advantages:
  - It protects thread_info from corruption in the case of stack
    overflows.
  - Its address is harder to determine if stack addresses are leaked,
    making a number of attacks more difficult.

This has the following consequences:
  - thread_info is now located at the beginning of task_struct.
  - The 'cpu' field is now in task_struct, and only exists when
    CONFIG_SMP is active.
  - thread_info doesn't have anymore the 'task' field.

This patch:
  - Removes all recopy of thread_info struct when the stack changes.
  - Changes the CURRENT_THREAD_INFO() macro to point to current.
  - Selects CONFIG_THREAD_INFO_IN_TASK.
  - Modifies raw_smp_processor_id() to get ->cpu from current without
    including linux/sched.h to avoid circular inclusion and without
    including asm/asm-offsets.h to avoid symbol names duplication
    between ASM constants and C constants.
  - Modifies klp_init_thread_info() to take a task_struct pointer
    argument.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Add task_stack.h to livepatch.h to fix build fails]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Christophe Leroy 2019-01-31 10:08:58 +00:00 committed by Michael Ellerman
parent 7aef376679
commit ed1cd6deb0
21 changed files with 56 additions and 194 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/powerpc/Kconfig
View File

@ -238,6 +238,7 @@ config PPC
select RTC_LIB
select SPARSE_IRQ
select SYSCTL_EXCEPTION_TRACE
select THREAD_INFO_IN_TASK
select VIRT_TO_BUS if !PPC64
#
# Please keep this list sorted alphabetically.

7
arch/powerpc/Makefile
View File

@ -427,6 +427,13 @@ else
endif
endif
ifdef CONFIG_SMP
prepare: task_cpu_prepare
task_cpu_prepare: prepare0
$(eval KBUILD_CFLAGS += -D_TASK_CPU=$(shell awk '{if ($$2 == "TI_CPU") print $$3;}' include/generated/asm-offsets.h))
endif
# Check toolchain versions:
# - gcc-4.6 is the minimum kernel-wide version so nothing required.
checkbin:

4
arch/powerpc/include/asm/irq.h
View File

@ -51,9 +51,6 @@ struct pt_regs;
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 exc_lvl_ctx_init(void);
#else
#define exc_lvl_ctx_init()
#endif
/*
@ -62,7 +59,6 @@ extern void exc_lvl_ctx_init(void);
extern struct thread_info *hardirq_ctx[NR_CPUS];
extern struct thread_info *softirq_ctx[NR_CPUS];
extern void irq_ctx_init(void);
void call_do_softirq(void *sp);
void call_do_irq(struct pt_regs *regs, void *sp);
extern void do_IRQ(struct pt_regs *regs);

7
arch/powerpc/include/asm/livepatch.h
View File

@ -21,6 +21,7 @@
#include <linux/module.h>
#include <linux/ftrace.h>
#include <linux/sched/task_stack.h>
#ifdef CONFIG_LIVEPATCH
static inline int klp_check_compiler_support(void)
@ -43,13 +44,13 @@ static inline unsigned long klp_get_ftrace_location(unsigned long faddr)
return ftrace_location_range(faddr, faddr + 16);
}
static inline void klp_init_thread_info(struct thread_info *ti)
static inline void klp_init_thread_info(struct task_struct *p)
{
/* + 1 to account for STACK_END_MAGIC */
ti->livepatch_sp = (unsigned long *)(ti + 1) + 1;
task_thread_info(p)->livepatch_sp = end_of_stack(p) + 1;
}
#else
static void klp_init_thread_info(struct thread_info *ti) { }
static inline void klp_init_thread_info(struct task_struct *p) { }
#endif /* CONFIG_LIVEPATCH */
#endif /* _ASM_POWERPC_LIVEPATCH_H */

17
arch/powerpc/include/asm/smp.h
View File

@ -83,7 +83,22 @@ int is_cpu_dead(unsigned int cpu);
/* 32-bit */
extern int smp_hw_index[];
#define raw_smp_processor_id() (current_thread_info()->cpu)
/*
* This is particularly ugly: it appears we can't actually get the definition
* of task_struct here, but we need access to the CPU this task is running on.
* Instead of using task_struct we're using _TASK_CPU which is extracted from
* asm-offsets.h by kbuild to get the current processor ID.
*
* This also needs to be safeguarded when building asm-offsets.s because at
* that time _TASK_CPU is not defined yet. It could have been guarded by
* _TASK_CPU itself, but we want the build to fail if _TASK_CPU is missing
* when building something else than asm-offsets.s
*/
#ifdef GENERATING_ASM_OFFSETS
#define raw_smp_processor_id() (0)
#else
#define raw_smp_processor_id() (*(unsigned int *)((void *)current + _TASK_CPU))
#endif
#define hard_smp_processor_id() (smp_hw_index[smp_processor_id()])
static inline int get_hard_smp_processor_id(int cpu)

17
arch/powerpc/include/asm/thread_info.h
View File

@ -18,9 +18,9 @@
#define THREAD_SIZE (1 << THREAD_SHIFT)
#ifdef CONFIG_PPC64
#define CURRENT_THREAD_INFO(dest, sp) stringify_in_c(clrrdi dest, sp, THREAD_SHIFT)
#define CURRENT_THREAD_INFO(dest, sp) stringify_in_c(ld dest, PACACURRENT(r13))
#else
#define CURRENT_THREAD_INFO(dest, sp) stringify_in_c(rlwinm dest, sp, 0, 0, 31-THREAD_SHIFT)
#define CURRENT_THREAD_INFO(dest, sp) stringify_in_c(mr dest, r2)
#endif
#ifndef __ASSEMBLY__
@ -34,8 +34,6 @@
* low level task data.
*/
struct thread_info {
struct task_struct *task; /* main task structure */
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable,
<0 => BUG */
unsigned long local_flags; /* private flags for thread */
@ -58,8 +56,6 @@ struct thread_info {
*/
#define INIT_THREAD_INFO(tsk) \
{ \
.task = &tsk, \
.cpu = 0, \
.preempt_count = INIT_PREEMPT_COUNT, \
.flags = 0, \
}
@ -67,15 +63,6 @@ struct thread_info {
#define THREAD_SIZE_ORDER (THREAD_SHIFT - PAGE_SHIFT)
/* how to get the thread information struct from C */
static inline struct thread_info *current_thread_info(void)
{
unsigned long val;
asm (CURRENT_THREAD_INFO(%0,1) : "=r" (val));
return (struct thread_info *)val;
}
extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
#ifdef CONFIG_PPC_BOOK3S_64

7
arch/powerpc/kernel/asm-offsets.c
View File

@ -13,6 +13,8 @@
* 2 of the License, or (at your option) any later version.
*/
#define GENERATING_ASM_OFFSETS /* asm/smp.h */
#include <linux/compat.h>
#include <linux/signal.h>
#include <linux/sched.h>
@ -97,6 +99,9 @@ int main(void)
#endif
#endif /* CONFIG_PPC64 */
OFFSET(TASK_STACK, task_struct, stack);
#ifdef CONFIG_SMP
OFFSET(TI_CPU, task_struct, cpu);
#endif
#ifdef CONFIG_LIVEPATCH
OFFSET(TI_livepatch_sp, thread_info, livepatch_sp);
@ -164,8 +169,6 @@ int main(void)
OFFSET(TI_FLAGS, thread_info, flags);
OFFSET(TI_LOCAL_FLAGS, thread_info, local_flags);
OFFSET(TI_PREEMPT, thread_info, preempt_count);
OFFSET(TI_TASK, thread_info, task);
OFFSET(TI_CPU, thread_info, cpu);
#ifdef CONFIG_PPC64
OFFSET(DCACHEL1BLOCKSIZE, ppc64_caches, l1d.block_size);

9
arch/powerpc/kernel/entry_32.S
View File

@ -1165,10 +1165,6 @@ ret_from_debug_exc:
mfspr r9,SPRN_SPRG_THREAD
lwz r10,SAVED_KSP_LIMIT(r1)
stw r10,KSP_LIMIT(r9)
lwz r9,TASK_STACK-THREAD(r9)
CURRENT_THREAD_INFO(r10, r1)
lwz r10,TI_PREEMPT(r10)
stw r10,TI_PREEMPT(r9)
RESTORE_xSRR(SRR0,SRR1);
RESTORE_xSRR(CSRR0,CSRR1);
RESTORE_MMU_REGS;
@ -1291,10 +1287,13 @@ BEGIN_FTR_SECTION
END_FTR_SECTION_IFSET(CPU_FTR_601)
lwz r3,_TRAP(r1)
andi. r0,r3,1
beq 4f
beq 5f
SAVE_NVGPRS(r1)
rlwinm r3,r3,0,0,30
stw r3,_TRAP(r1)
5: mfspr r2,SPRN_SPRG_THREAD
addi r2,r2,-THREAD
tovirt(r2,r2) /* set back r2 to current */
4: addi r3,r1,STACK_FRAME_OVERHEAD
bl unrecoverable_exception
/* shouldn't return */

11
arch/powerpc/kernel/exceptions-64e.S
View File

@ -77,17 +77,6 @@ special_reg_save:
andi. r3,r3,MSR_PR
bnelr
/* Copy info into temporary exception thread info */
ld r11,PACAKSAVE(r13)
CURRENT_THREAD_INFO(r11, r11)
CURRENT_THREAD_INFO(r12, r1)
ld r10,TI_FLAGS(r11)
std r10,TI_FLAGS(r12)
ld r10,TI_PREEMPT(r11)
std r10,TI_PREEMPT(r12)
ld r10,TI_TASK(r11)
std r10,TI_TASK(r12)
/*
* Advance to the next TLB exception frame for handler
* types that don't do it automatically.

6
arch/powerpc/kernel/head_32.S
View File

@ -834,9 +834,9 @@ __secondary_start:
/* get current's stack and current */
lis r1,secondary_ti@ha
tophys(r1,r1)
lwz r1,secondary_ti@l(r1)
tophys(r2,r1)
lwz r2,TI_TASK(r2)
lwz r2,secondary_ti@l(r1)
tophys(r1,r2)
lwz r1,TASK_STACK(r1)
/* stack */
addi r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD

4
arch/powerpc/kernel/head_44x.S
View File

@ -1021,8 +1021,8 @@ _GLOBAL(start_secondary_47x)
/* Get current's stack and current */
lis r1,secondary_ti@ha
lwz r1,secondary_ti@l(r1)
lwz r2,TI_TASK(r1)
lwz r2,secondary_ti@l(r1)
lwz r1,TASK_STACK(r2)
/* Current stack pointer */
addi r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD

8
arch/powerpc/kernel/head_booke.h
View File

@ -155,13 +155,7 @@ END_BTB_FLUSH_SECTION
stw r10,GPR11(r11); \
b 2f; \
/* COMING FROM PRIV MODE */ \
1: lwz r9,TI_FLAGS-EXC_LVL_FRAME_OVERHEAD(r11); \
lwz r10,TI_PREEMPT-EXC_LVL_FRAME_OVERHEAD(r11); \
stw r9,TI_FLAGS-EXC_LVL_FRAME_OVERHEAD(r8); \
stw r10,TI_PREEMPT-EXC_LVL_FRAME_OVERHEAD(r8); \
lwz r9,TI_TASK-EXC_LVL_FRAME_OVERHEAD(r11); \
stw r9,TI_TASK-EXC_LVL_FRAME_OVERHEAD(r8); \
mr r11,r8; \
1: mr r11, r8; \
2: mfspr r8,SPRN_SPRG_RSCRATCH_##exc_level; \
stw r12,GPR12(r11); /* save various registers */\
mflr r10; \

7
arch/powerpc/kernel/head_fsl_booke.S
View File

@ -719,8 +719,7 @@ finish_tlb_load:
/* Get the next_tlbcam_idx percpu var */
#ifdef CONFIG_SMP
lwz r12, TASK_STACK-THREAD(r12)
lwz r15, TI_CPU(r12)
lwz r15, TI_CPU-THREAD(r12)
lis r14, __per_cpu_offset@h
ori r14, r14, __per_cpu_offset@l
rlwinm r15, r15, 2, 0, 29
@ -1093,8 +1092,8 @@ __secondary_start:
/* get current's stack and current */
lis r1,secondary_ti@ha
lwz r1,secondary_ti@l(r1)
lwz r2,TI_TASK(r1)
lwz r2,secondary_ti@l(r1)
lwz r1,TASK_STACK(r2)
/* stack */
addi r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD

79
arch/powerpc/kernel/irq.c
View File

@ -673,24 +673,9 @@ void do_IRQ(struct pt_regs *regs)
set_irq_regs(old_regs);
return;
}
/* Prepare the thread_info in the irq stack */
irqtp->task = curtp->task;
irqtp->flags = 0;
/* Copy the preempt_count so that the [soft]irq checks work. */
irqtp->preempt_count = curtp->preempt_count;
/* Switch stack and call */
call_do_irq(regs, irqtp);
/* Restore stack limit */
irqtp->task = NULL;
/* Copy back updates to the thread_info */
if (irqtp->flags)
set_bits(irqtp->flags, &curtp->flags);
set_irq_regs(old_regs);
}
@ -698,85 +683,23 @@ void __init init_IRQ(void)
{
if (ppc_md.init_IRQ)
ppc_md.init_IRQ();
exc_lvl_ctx_init();
irq_ctx_init();
}
#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 exc_lvl_ctx_init(void)
{
struct thread_info *tp;
int i, cpu_nr;
for_each_possible_cpu(i) {
#ifdef CONFIG_PPC64
cpu_nr = i;
#else
#ifdef CONFIG_SMP
cpu_nr = get_hard_smp_processor_id(i);
#else
cpu_nr = 0;
#endif
#endif
tp = critirq_ctx[cpu_nr];
tp->cpu = cpu_nr;
tp->preempt_count = 0;
#ifdef CONFIG_BOOKE
tp = dbgirq_ctx[cpu_nr];
tp->cpu = cpu_nr;
tp->preempt_count = 0;
tp = mcheckirq_ctx[cpu_nr];
tp->cpu = cpu_nr;
tp->preempt_count = HARDIRQ_OFFSET;
#endif
}
}
#endif
struct thread_info *softirq_ctx[NR_CPUS] __read_mostly;
struct thread_info *hardirq_ctx[NR_CPUS] __read_mostly;
void irq_ctx_init(void)
{
struct thread_info *tp;
int i;
for_each_possible_cpu(i) {
tp = softirq_ctx[i];
tp->cpu = i;
klp_init_thread_info(tp);
tp = hardirq_ctx[i];
tp->cpu = i;
klp_init_thread_info(tp);
}
}
void do_softirq_own_stack(void)
{
struct thread_info *curtp, *irqtp;
struct thread_info *irqtp;
curtp = current_thread_info();
irqtp = softirq_ctx[smp_processor_id()];
irqtp->task = curtp->task;
irqtp->flags = 0;
call_do_softirq(irqtp);
irqtp->task = NULL;
/* Set any flag that may have been set on the
* alternate stack
*/
if (irqtp->flags)
set_bits(irqtp->flags, &curtp->flags);
}
irq_hw_number_t virq_to_hw(unsigned int virq)

28
arch/powerpc/kernel/kgdb.c
View File

@ -151,41 +151,13 @@ static int kgdb_handle_breakpoint(struct pt_regs *regs)
return 1;
}
static DEFINE_PER_CPU(struct thread_info, kgdb_thread_info);
static int kgdb_singlestep(struct pt_regs *regs)
{
struct thread_info *thread_info, *exception_thread_info;
struct thread_info *backup_current_thread_info =
this_cpu_ptr(&kgdb_thread_info);
if (user_mode(regs))
return 0;
/*
* On Book E and perhaps other processors, singlestep is handled on
* the critical exception stack. This causes current_thread_info()
* to fail, since it it locates the thread_info by masking off
* the low bits of the current stack pointer. We work around
* this issue by copying the thread_info from the kernel stack
* before calling kgdb_handle_exception, and copying it back
* afterwards. On most processors the copy is avoided since
* exception_thread_info == thread_info.
*/
thread_info = (struct thread_info *)(regs->gpr[1] & ~(THREAD_SIZE-1));
exception_thread_info = current_thread_info();
if (thread_info != exception_thread_info) {
/* Save the original current_thread_info. */
memcpy(backup_current_thread_info, exception_thread_info, sizeof *thread_info);
memcpy(exception_thread_info, thread_info, sizeof *thread_info);
}
kgdb_handle_exception(0, SIGTRAP, 0, regs);
if (thread_info != exception_thread_info)
/* Restore current_thread_info lastly. */
memcpy(exception_thread_info, backup_current_thread_info, sizeof *thread_info);
return 1;
}

6
arch/powerpc/kernel/machine_kexec_64.c
View File

@ -317,10 +317,8 @@ void default_machine_kexec(struct kimage *image)
* We setup preempt_count to avoid using VMX in memcpy.
* XXX: the task struct will likely be invalid once we do the copy!
*/
kexec_stack.thread_info.task = current_thread_info()->task;
kexec_stack.thread_info.flags = 0;
kexec_stack.thread_info.preempt_count = HARDIRQ_OFFSET;
kexec_stack.thread_info.cpu = current_thread_info()->cpu;
current_thread_info()->flags = 0;
current_thread_info()->preempt_count = HARDIRQ_OFFSET;
/* We need a static PACA, too; copy this CPU's PACA over and switch to
* it. Also poison per_cpu_offset and NULL lppaca to catch anyone using

2
arch/powerpc/kernel/process.c
View File

@ -1634,7 +1634,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
struct thread_info *ti = task_thread_info(p);
klp_init_thread_info(ti);
klp_init_thread_info(p);
/* Copy registers */
sp -= sizeof(struct pt_regs);

2
arch/powerpc/kernel/setup-common.c
View File

@ -937,7 +937,7 @@ void __init setup_arch(char **cmdline_p)
/* Reserve large chunks of memory for use by CMA for KVM. */
kvm_cma_reserve();
klp_init_thread_info(&init_thread_info);
klp_init_thread_info(&init_task);
init_mm.start_code = (unsigned long)_stext;
init_mm.end_code = (unsigned long) _etext;

21
arch/powerpc/kernel/setup_64.c
View File

@ -689,24 +689,6 @@ void __init exc_lvl_early_init(void)
}
#endif
/*
* Emergency stacks are used for a range of things, from asynchronous
* NMIs (system reset, machine check) to synchronous, process context.
* We set preempt_count to zero, even though that isn't necessarily correct. To
* get the right value we'd need to copy it from the previous thread_info, but
* doing that might fault causing more problems.
* TODO: what to do with accounting?
*/
static void emerg_stack_init_thread_info(struct thread_info *ti, int cpu)
{
ti->task = NULL;
ti->cpu = cpu;
ti->preempt_count = 0;
ti->local_flags = 0;
ti->flags = 0;
klp_init_thread_info(ti);
}
/*
* Stack space used when we detect a bad kernel stack pointer, and
* early in SMP boots before relocation is enabled. Exclusive emergency
@ -737,18 +719,15 @@ void __init emergency_stack_init(void)
struct thread_info *ti;
ti = alloc_stack(limit, i);
emerg_stack_init_thread_info(ti, i);
paca_ptrs[i]->emergency_sp = (void *)ti + THREAD_SIZE;
#ifdef CONFIG_PPC_BOOK3S_64
/* emergency stack for NMI exception handling. */
ti = alloc_stack(limit, i);
emerg_stack_init_thread_info(ti, i);
paca_ptrs[i]->nmi_emergency_sp = (void *)ti + THREAD_SIZE;
/* emergency stack for machine check exception handling. */
ti = alloc_stack(limit, i);
emerg_stack_init_thread_info(ti, i);
paca_ptrs[i]->mc_emergency_sp = (void *)ti + THREAD_SIZE;
#endif
}

2
arch/powerpc/kernel/smp.c
View File

@ -988,7 +988,7 @@ static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle)
paca_ptrs[cpu]->kstack = (unsigned long)task_stack_page(idle) +
THREAD_SIZE - STACK_FRAME_OVERHEAD;
#endif
ti->cpu = cpu;
idle->cpu = cpu;
secondary_ti = current_set[cpu] = ti;
}

5
arch/powerpc/net/bpf_jit32.h
View File

@ -106,9 +106,8 @@ DECLARE_LOAD_FUNC(sk_load_byte_msh);
} while (0)
#else
#define PPC_BPF_LOAD_CPU(r) \
do { BUILD_BUG_ON(FIELD_SIZEOF(struct thread_info, cpu) != 4); \
PPC_LHZ_OFFS(r, (1 & ~(THREAD_SIZE - 1)), \
offsetof(struct thread_info, cpu)); \
do { BUILD_BUG_ON(FIELD_SIZEOF(struct task_struct, cpu) != 4); \
PPC_LHZ_OFFS(r, 2, offsetof(struct task_struct, cpu)); \
} while(0)
#endif
#else