[PATCH v6 0/9] powerpc: Switch to CONFIG_THREAD_INFO_IN_TASK

[PATCH v6 0/9] powerpc: Switch to CONFIG_THREAD_INFO_IN_TASK

[Christophe Leroy]

The purpose of this serie is to activate 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.

Changes since v5:
 - Fixed livepatch_sp setup by using end_of_stack() instead of hardcoding
 - Fixed PPC_BPF_LOAD_CPU() macro

Changes since v4:
 - Fixed a build failure on 32bits SMP when include/generated/asm-offsets.h is not
 already existing, was due to spaces instead of a tab in the Makefile

Changes since RFC v3: (based on Nick's review)
 - Renamed task_size.h to task_size_user64.h to better relate to what it contains.
 - Handling of the isolation of thread_info cpu field inside CONFIG_SMP #ifdefs moved to a separate patch.
 - Removed CURRENT_THREAD_INFO macro completely.
 - Added a guard in asm/smp.h to avoid build failure before _TASK_CPU is defined.
 - Added a patch at the end to rename 'tp' pointers to 'sp' pointers
 - Renamed 'tp' into 'sp' pointers in preparation patch when relevant
 - Fixed a few commit logs
 - Fixed checkpatch report.

Changes since RFC v2:
 - Removed the modification of names in asm-offsets
 - Created a rule in arch/powerpc/Makefile to append the offset of current->cpu in CFLAGS
 - Modified asm/smp.h to use the offset set in CFLAGS
 - Squashed the renaming of THREAD_INFO to TASK_STACK in the preparation patch
 - Moved the modification of current_pt_regs in the patch activating CONFIG_THREAD_INFO_IN_TASK

Changes since RFC v1:
 - Removed the first patch which was modifying header inclusion order in timer
 - Modified some names in asm-offsets to avoid conflicts when including asm-offsets in C files
 - Modified asm/smp.h to avoid having to include linux/sched.h (using asm-offsets instead)
 - Moved some changes from the activation patch to the preparation patch.

Christophe Leroy (9):
  book3s/64: avoid circular header inclusion in mmu-hash.h
  powerpc: Only use task_struct 'cpu' field on SMP
  powerpc: Prepare for moving thread_info into task_struct
  powerpc: Activate CONFIG_THREAD_INFO_IN_TASK
  powerpc: regain entire stack space
  powerpc: 'current_set' is now a table of task_struct pointers
  powerpc/32: Remove CURRENT_THREAD_INFO and rename TI_CPU
  powerpc/64: Remove CURRENT_THREAD_INFO
  powerpc: clean stack pointers naming

 arch/powerpc/Kconfig                           |  1 +
 arch/powerpc/Makefile                          |  8 ++-
 arch/powerpc/include/asm/asm-prototypes.h      |  4 +-
 arch/powerpc/include/asm/book3s/64/mmu-hash.h  |  2 +-
 arch/powerpc/include/asm/exception-64s.h       |  4 +-
 arch/powerpc/include/asm/irq.h                 | 14 ++---
 arch/powerpc/include/asm/livepatch.h           |  7 ++-
 arch/powerpc/include/asm/processor.h           | 39 +------------
 arch/powerpc/include/asm/ptrace.h              |  2 +-
 arch/powerpc/include/asm/reg.h                 |  2 +-
 arch/powerpc/include/asm/smp.h                 | 17 +++++-
 arch/powerpc/include/asm/task_size_user64.h    | 42 ++++++++++++++
 arch/powerpc/include/asm/thread_info.h         | 19 -------
 arch/powerpc/kernel/asm-offsets.c              | 10 ++--
 arch/powerpc/kernel/entry_32.S                 | 66 ++++++++--------------
 arch/powerpc/kernel/entry_64.S                 | 12 ++--
 arch/powerpc/kernel/epapr_hcalls.S             |  5 +-
 arch/powerpc/kernel/exceptions-64e.S           | 13 +----
 arch/powerpc/kernel/exceptions-64s.S           |  2 +-
 arch/powerpc/kernel/head_32.S                  | 14 ++---
 arch/powerpc/kernel/head_40x.S                 |  4 +-
 arch/powerpc/kernel/head_44x.S                 |  8 +--
 arch/powerpc/kernel/head_64.S                  |  1 +
 arch/powerpc/kernel/head_8xx.S                 |  2 +-
 arch/powerpc/kernel/head_booke.h               | 12 +---
 arch/powerpc/kernel/head_fsl_booke.S           | 16 +++---
 arch/powerpc/kernel/idle_6xx.S                 |  8 +--
 arch/powerpc/kernel/idle_book3e.S              |  2 +-
 arch/powerpc/kernel/idle_e500.S                |  8 +--
 arch/powerpc/kernel/idle_power4.S              |  2 +-
 arch/powerpc/kernel/irq.c                      | 77 +++++---------------------
 arch/powerpc/kernel/kgdb.c                     | 28 ----------
 arch/powerpc/kernel/machine_kexec_64.c         |  6 +-
 arch/powerpc/kernel/misc_32.S                  | 17 +++---
 arch/powerpc/kernel/process.c                  | 17 +++---
 arch/powerpc/kernel/setup-common.c             |  2 +-
 arch/powerpc/kernel/setup_32.c                 | 15 ++---
 arch/powerpc/kernel/setup_64.c                 | 41 ++++----------
 arch/powerpc/kernel/smp.c                      | 16 +++---
 arch/powerpc/kernel/trace/ftrace_64_mprofile.S |  6 +-
 arch/powerpc/kvm/book3s_hv_hmi.c               |  1 +
 arch/powerpc/mm/hash_low_32.S                  | 14 ++---
 arch/powerpc/net/bpf_jit32.h                   |  5 +-
 arch/powerpc/sysdev/6xx-suspend.S              |  5 +-
 arch/powerpc/xmon/xmon.c                       |  2 +-
 45 files changed, 230 insertions(+), 368 deletions(-)
 create mode 100644 arch/powerpc/include/asm/task_size_user64.h

-- 
2.13.3

[PATCH v6 1/9] book3s/64: avoid circular header inclusion in mmu-hash.h

[Christophe Leroy]

When activating CONFIG_THREAD_INFO_IN_TASK, linux/sched.h
includes asm/current.h. This generates a circular dependency.
To avoid that, asm/processor.h shall not be included in mmu-hash.h

In order to do that, this patch moves into a new header called
asm/task_size_user64.h the information from asm/processor.h required
by mmu-hash.h

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/include/asm/book3s/64/mmu-hash.h |  2 +-
 arch/powerpc/include/asm/processor.h          | 34 +---------------------
 arch/powerpc/include/asm/task_size_user64.h   | 42 +++++++++++++++++++++++++++
 arch/powerpc/kvm/book3s_hv_hmi.c              |  1 +
 4 files changed, 45 insertions(+), 34 deletions(-)
 create mode 100644 arch/powerpc/include/asm/task_size_user64.h

diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
index e0e4ce8f77d6..02955d867067 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
@@ -23,7 +23,7 @@
  */
 #include <asm/book3s/64/pgtable.h>
 #include <asm/bug.h>
-#include <asm/processor.h>
+#include <asm/task_size_user64.h>
 #include <asm/cpu_has_feature.h>
 
 /*
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 52fadded5c1e..13589274fe9b 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -101,40 +101,8 @@ void release_thread(struct task_struct *);
 #endif
 
 #ifdef CONFIG_PPC64
-/*
- * 64-bit user address space can have multiple limits
- * For now supported values are:
- */
-#define TASK_SIZE_64TB  (0x0000400000000000UL)
-#define TASK_SIZE_128TB (0x0000800000000000UL)
-#define TASK_SIZE_512TB (0x0002000000000000UL)
-#define TASK_SIZE_1PB   (0x0004000000000000UL)
-#define TASK_SIZE_2PB   (0x0008000000000000UL)
-/*
- * With 52 bits in the address we can support
- * upto 4PB of range.
- */
-#define TASK_SIZE_4PB   (0x0010000000000000UL)
 
-/*
- * For now 512TB is only supported with book3s and 64K linux page size.
- */
-#if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_PPC_64K_PAGES)
-/*
- * Max value currently used:
- */
-#define TASK_SIZE_USER64		TASK_SIZE_4PB
-#define DEFAULT_MAP_WINDOW_USER64	TASK_SIZE_128TB
-#define TASK_CONTEXT_SIZE		TASK_SIZE_512TB
-#else
-#define TASK_SIZE_USER64		TASK_SIZE_64TB
-#define DEFAULT_MAP_WINDOW_USER64	TASK_SIZE_64TB
-/*
- * We don't need to allocate extended context ids for 4K page size, because
- * we limit the max effective address on this config to 64TB.
- */
-#define TASK_CONTEXT_SIZE		TASK_SIZE_64TB
-#endif
+#include <asm/task_size_user64.h>
 
 /*
  * 32-bit user address space is 4GB - 1 page
diff --git a/arch/powerpc/include/asm/task_size_user64.h b/arch/powerpc/include/asm/task_size_user64.h
new file mode 100644
index 000000000000..a4043075864b
--- /dev/null
+++ b/arch/powerpc/include/asm/task_size_user64.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_POWERPC_TASK_SIZE_USER64_H
+#define _ASM_POWERPC_TASK_SIZE_USER64_H
+
+#ifdef CONFIG_PPC64
+/*
+ * 64-bit user address space can have multiple limits
+ * For now supported values are:
+ */
+#define TASK_SIZE_64TB  (0x0000400000000000UL)
+#define TASK_SIZE_128TB (0x0000800000000000UL)
+#define TASK_SIZE_512TB (0x0002000000000000UL)
+#define TASK_SIZE_1PB   (0x0004000000000000UL)
+#define TASK_SIZE_2PB   (0x0008000000000000UL)
+/*
+ * With 52 bits in the address we can support
+ * upto 4PB of range.
+ */
+#define TASK_SIZE_4PB   (0x0010000000000000UL)
+
+/*
+ * For now 512TB is only supported with book3s and 64K linux page size.
+ */
+#if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_PPC_64K_PAGES)
+/*
+ * Max value currently used:
+ */
+#define TASK_SIZE_USER64		TASK_SIZE_4PB
+#define DEFAULT_MAP_WINDOW_USER64	TASK_SIZE_128TB
+#define TASK_CONTEXT_SIZE		TASK_SIZE_512TB
+#else
+#define TASK_SIZE_USER64		TASK_SIZE_64TB
+#define DEFAULT_MAP_WINDOW_USER64	TASK_SIZE_64TB
+/*
+ * We don't need to allocate extended context ids for 4K page size, because
+ * we limit the max effective address on this config to 64TB.
+ */
+#define TASK_CONTEXT_SIZE		TASK_SIZE_64TB
+#endif
+
+#endif /* CONFIG_PPC64 */
+#endif /* _ASM_POWERPC_TASK_SIZE_USER64_H */
diff --git a/arch/powerpc/kvm/book3s_hv_hmi.c b/arch/powerpc/kvm/book3s_hv_hmi.c
index e3f738eb1cac..64b5011475c7 100644
--- a/arch/powerpc/kvm/book3s_hv_hmi.c
+++ b/arch/powerpc/kvm/book3s_hv_hmi.c
@@ -24,6 +24,7 @@
 #include <linux/compiler.h>
 #include <asm/paca.h>
 #include <asm/hmi.h>
+#include <asm/processor.h>
 
 void wait_for_subcore_guest_exit(void)
 {
-- 
2.13.3

[PATCH v6 2/9] powerpc: Only use task_struct 'cpu' field on SMP

[Christophe Leroy]

When moving to CONFIG_THREAD_INFO_IN_TASK, the thread_info 'cpu' field
gets moved into task_struct and only defined when CONFIG_SMP is set.

This patch ensures that TI_CPU is only used when CONFIG_SMP is set and
that task_struct 'cpu' field is not used directly out of SMP code.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kernel/head_fsl_booke.S | 2 ++
 arch/powerpc/kernel/misc_32.S        | 4 ++++
 arch/powerpc/xmon/xmon.c             | 2 +-
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index e2750b856c8f..05b574f416b3 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -243,8 +243,10 @@ set_ivor:
 	li	r0,0
 	stwu	r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
 
+#ifdef CONFIG_SMP
 	CURRENT_THREAD_INFO(r22, r1)
 	stw	r24, TI_CPU(r22)
+#endif
 
 	bl	early_init
 
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index 695b24a2d954..2f0fe8bfc078 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -183,10 +183,14 @@ _GLOBAL(low_choose_750fx_pll)
 	or	r4,r4,r5
 	mtspr	SPRN_HID1,r4
 
+#ifdef CONFIG_SMP
 	/* Store new HID1 image */
 	CURRENT_THREAD_INFO(r6, r1)
 	lwz	r6,TI_CPU(r6)
 	slwi	r6,r6,2
+#else
+	li	r6, 0
+#endif
 	addis	r6,r6,nap_save_hid1@ha
 	stw	r4,nap_save_hid1@l(r6)
 
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index c70d17c9a6ba..1731793e1277 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -2986,7 +2986,7 @@ static void show_task(struct task_struct *tsk)
 	printf("%px %016lx %6d %6d %c %2d %s\n", tsk,
 		tsk->thread.ksp,
 		tsk->pid, tsk->parent->pid,
-		state, task_thread_info(tsk)->cpu,
+		state, task_cpu(tsk),
 		tsk->comm);
 }
 
-- 
2.13.3

[PATCH v6 3/9] powerpc: Prepare for moving thread_info into task_struct

[Christophe Leroy]

This patch cleans the powerpc kernel before activating
CONFIG_THREAD_INFO_IN_TASK:
- The purpose of the pointer given to call_do_softirq() and
call_do_irq() is to point the new stack ==> change it to void* and
rename it 'sp'
- Don't use CURRENT_THREAD_INFO() to locate the stack.
- Fix a few comments.
- Replace current_thread_info()->task by current
- Remove unnecessary casts to thread_info, as they'll become invalid
once thread_info is not in stack anymore.
- Rename THREAD_INFO to TASK_STASK: as it is in fact the offset of the
pointer to the stack in task_struct, this pointer will not be impacted
by the move of THREAD_INFO.
- Makes TASK_STACK available to PPC64. PPC64 will need it to get the
stack pointer from current once the thread_info have been moved.
- Modifies klp_init_thread_info() to take task_struct pointer argument.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/include/asm/irq.h       |  4 ++--
 arch/powerpc/include/asm/livepatch.h |  7 ++++---
 arch/powerpc/include/asm/processor.h |  4 ++--
 arch/powerpc/include/asm/reg.h       |  2 +-
 arch/powerpc/kernel/asm-offsets.c    |  2 +-
 arch/powerpc/kernel/entry_32.S       |  2 +-
 arch/powerpc/kernel/entry_64.S       |  2 +-
 arch/powerpc/kernel/head_32.S        |  4 ++--
 arch/powerpc/kernel/head_40x.S       |  4 ++--
 arch/powerpc/kernel/head_44x.S       |  2 +-
 arch/powerpc/kernel/head_8xx.S       |  2 +-
 arch/powerpc/kernel/head_booke.h     |  4 ++--
 arch/powerpc/kernel/head_fsl_booke.S |  4 ++--
 arch/powerpc/kernel/irq.c            |  2 +-
 arch/powerpc/kernel/misc_32.S        |  4 ++--
 arch/powerpc/kernel/process.c        |  8 ++++----
 arch/powerpc/kernel/setup-common.c   |  2 +-
 arch/powerpc/kernel/setup_32.c       | 15 +++++----------
 arch/powerpc/kernel/smp.c            |  4 +++-
 19 files changed, 38 insertions(+), 40 deletions(-)

diff --git a/arch/powerpc/include/asm/irq.h b/arch/powerpc/include/asm/irq.h
index ee39ce56b2a2..2efbae8d93be 100644
--- a/arch/powerpc/include/asm/irq.h
+++ b/arch/powerpc/include/asm/irq.h
@@ -63,8 +63,8 @@ extern struct thread_info *hardirq_ctx[NR_CPUS];
 extern struct thread_info *softirq_ctx[NR_CPUS];
 
 extern void irq_ctx_init(void);
-extern void call_do_softirq(struct thread_info *tp);
-extern void call_do_irq(struct pt_regs *regs, struct thread_info *tp);
+void call_do_softirq(void *sp);
+void call_do_irq(struct pt_regs *regs, void *sp);
 extern void do_IRQ(struct pt_regs *regs);
 extern void __init init_IRQ(void);
 extern void __do_irq(struct pt_regs *regs);
diff --git a/arch/powerpc/include/asm/livepatch.h b/arch/powerpc/include/asm/livepatch.h
index 47a03b9b528b..8a81d10ccc82 100644
--- a/arch/powerpc/include/asm/livepatch.h
+++ b/arch/powerpc/include/asm/livepatch.h
@@ -43,13 +43,14 @@ 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)
 {
+	struct thread_info *ti = task_thread_info(p);
 	/* + 1 to account for STACK_END_MAGIC */
-	ti->livepatch_sp = (unsigned long *)(ti + 1) + 1;
+	ti->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 */
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 13589274fe9b..b225c7f7c5a4 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -40,7 +40,7 @@
 
 #ifndef __ASSEMBLY__
 #include <linux/types.h>
-#include <asm/thread_info.h>
+#include <linux/thread_info.h>
 #include <asm/ptrace.h>
 #include <asm/hw_breakpoint.h>
 
@@ -332,7 +332,7 @@ struct thread_struct {
 
 #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)
+	(_ALIGN_UP(sizeof(struct thread_info), 16) + (unsigned long)&init_stack)
 
 #ifdef CONFIG_SPE
 #define SPEFSCR_INIT \
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 640a4d818772..d2528a0b2f5b 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1058,7 +1058,7 @@
  *	- SPRG9 debug exception scratch
  *
  * All 32-bit:
- *	- SPRG3 current thread_info pointer
+ *	- SPRG3 current thread_struct physical addr pointer
  *        (virtual on BookE, physical on others)
  *
  * 32-bit classic:
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index a6d70fd2e499..c583a02e5a21 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -91,10 +91,10 @@ int main(void)
 	DEFINE(NMI_MASK, NMI_MASK);
 	OFFSET(TASKTHREADPPR, task_struct, thread.ppr);
 #else
-	OFFSET(THREAD_INFO, task_struct, stack);
 	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);
 
 #ifdef CONFIG_LIVEPATCH
 	OFFSET(TI_livepatch_sp, thread_info, livepatch_sp);
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 77decded1175..7ea1d71f4546 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -1166,7 +1166,7 @@ ret_from_debug_exc:
 	mfspr	r9,SPRN_SPRG_THREAD
 	lwz	r10,SAVED_KSP_LIMIT(r1)
 	stw	r10,KSP_LIMIT(r9)
-	lwz	r9,THREAD_INFO-THREAD(r9)
+	lwz	r9,TASK_STACK-THREAD(r9)
 	CURRENT_THREAD_INFO(r10, r1)
 	lwz	r10,TI_PREEMPT(r10)
 	stw	r10,TI_PREEMPT(r9)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index ed6f6c7f4264..6fce0f8fd8c4 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -684,7 +684,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
 2:
 #endif /* CONFIG_PPC_BOOK3S_64 */
 
-	CURRENT_THREAD_INFO(r7, r8)  /* base of new stack */
+	clrrdi	r7, r8, THREAD_SHIFT	/* base of new stack */
 	/* Note: this uses SWITCH_FRAME_SIZE rather than INT_FRAME_SIZE
 	   because we don't need to leave the 288-byte ABI gap at the
 	   top of the kernel stack. */
diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 61ca27929355..dce6f2ff07e5 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -261,7 +261,7 @@ __secondary_hold_acknowledge:
 	tophys(r11,r1);			/* use tophys(r1) if kernel */ \
 	beq	1f;		\
 	mfspr	r11,SPRN_SPRG_THREAD;	\
-	lwz	r11,THREAD_INFO-THREAD(r11);	\
+	lwz	r11,TASK_STACK-THREAD(r11);	\
 	addi	r11,r11,THREAD_SIZE;	\
 	tophys(r11,r11);	\
 1:	subi	r11,r11,INT_FRAME_SIZE	/* alloc exc. frame */
@@ -841,7 +841,7 @@ __secondary_start:
 	bl	init_idle_6xx
 #endif /* CONFIG_6xx */
 
-	/* get current_thread_info and current */
+	/* get current's stack and current */
 	lis	r1,secondary_ti@ha
 	tophys(r1,r1)
 	lwz	r1,secondary_ti@l(r1)
diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index b19d78410511..3088c9f29f5e 100644
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -115,7 +115,7 @@ _ENTRY(saved_ksp_limit)
 	andi.	r11,r11,MSR_PR;						     \
 	beq	1f;							     \
 	mfspr	r1,SPRN_SPRG_THREAD;	/* if from user, start at top of   */\
-	lwz	r1,THREAD_INFO-THREAD(r1); /* this thread's kernel stack   */\
+	lwz	r1,TASK_STACK-THREAD(r1); /* this thread's kernel stack   */\
 	addi	r1,r1,THREAD_SIZE;					     \
 1:	subi	r1,r1,INT_FRAME_SIZE;	/* Allocate an exception frame     */\
 	tophys(r11,r1);							     \
@@ -158,7 +158,7 @@ _ENTRY(saved_ksp_limit)
 	beq	1f;							     \
 	/* COMING FROM USER MODE */					     \
 	mfspr	r11,SPRN_SPRG_THREAD;	/* if from user, start at top of   */\
-	lwz	r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\
+	lwz	r11,TASK_STACK-THREAD(r11); /* this thread's kernel stack */\
 1:	addi	r11,r11,THREAD_SIZE-INT_FRAME_SIZE; /* Alloc an excpt frm  */\
 	tophys(r11,r11);						     \
 	stw	r10,_CCR(r11);          /* save various registers	   */\
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index 37e4a7cf0065..15d39b2499de 100644
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -1020,7 +1020,7 @@ _GLOBAL(start_secondary_47x)
 
 	/* Now we can get our task struct and real stack pointer */
 
-	/* Get current_thread_info and current */
+	/* Get current's stack and current */
 	lis	r1,secondary_ti@ha
 	lwz	r1,secondary_ti@l(r1)
 	lwz	r2,TI_TASK(r1)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 6582f824d620..e56e36aa2b3d 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -124,7 +124,7 @@ turn_on_mmu:
 	tophys(r11,r1);			/* use tophys(r1) if kernel */ \
 	beq	1f;		\
 	mfspr	r11,SPRN_SPRG_THREAD;	\
-	lwz	r11,THREAD_INFO-THREAD(r11);	\
+	lwz	r11,TASK_STACK-THREAD(r11);	\
 	addi	r11,r11,THREAD_SIZE;	\
 	tophys(r11,r11);	\
 1:	subi	r11,r11,INT_FRAME_SIZE	/* alloc exc. frame */
diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h
index d0862a100d29..175f812066dc 100644
--- a/arch/powerpc/kernel/head_booke.h
+++ b/arch/powerpc/kernel/head_booke.h
@@ -44,7 +44,7 @@
 	mr	r11, r1;						     \
 	beq	1f;							     \
 	/* if from user, start at top of this thread's kernel stack */       \
-	lwz	r11, THREAD_INFO-THREAD(r10);				     \
+	lwz	r11, TASK_STACK - THREAD(r10);				     \
 	ALLOC_STACK_FRAME(r11, THREAD_SIZE);				     \
 1 :	subi	r11, r11, INT_FRAME_SIZE; /* Allocate exception frame */     \
 	stw	r13, _CCR(r11);		/* save various registers */	     \
@@ -130,7 +130,7 @@
 	DO_KVM	BOOKE_INTERRUPT_##intno exc_level_srr1;		             \
 	andi.	r11,r11,MSR_PR;						     \
 	mfspr	r11,SPRN_SPRG_THREAD;	/* if from user, start at top of   */\
-	lwz	r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\
+	lwz	r11, TASK_STACK - THREAD(r11); /* this thread's kernel stack */\
 	addi	r11,r11,EXC_LVL_FRAME_OVERHEAD;	/* allocate stack frame    */\
 	beq	1f;							     \
 	/* COMING FROM USER MODE */					     \
diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index 05b574f416b3..239ad8a4754e 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -704,7 +704,7 @@ finish_tlb_load:
 
 	/* Get the next_tlbcam_idx percpu var */
 #ifdef CONFIG_SMP
-	lwz	r12, THREAD_INFO-THREAD(r12)
+	lwz	r12, TASK_STACK-THREAD(r12)
 	lwz	r15, TI_CPU(r12)
 	lis     r14, __per_cpu_offset@h
 	ori     r14, r14, __per_cpu_offset@l
@@ -1076,7 +1076,7 @@ __secondary_start:
 	mr	r4,r24		/* Why? */
 	bl	call_setup_cpu
 
-	/* get current_thread_info and current */
+	/* get current's stack and current */
 	lis	r1,secondary_ti@ha
 	lwz	r1,secondary_ti@l(r1)
 	lwz	r2,TI_TASK(r1)
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 916ddc4aac44..9e7dc4468c8c 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -663,7 +663,7 @@ void do_IRQ(struct pt_regs *regs)
 	struct thread_info *curtp, *irqtp, *sirqtp;
 
 	/* Switch to the irq stack to handle this */
-	curtp = current_thread_info();
+	curtp = (void *)(current_stack_pointer() & ~(THREAD_SIZE - 1));
 	irqtp = hardirq_ctx[raw_smp_processor_id()];
 	sirqtp = softirq_ctx[raw_smp_processor_id()];
 
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index 2f0fe8bfc078..32762f4c3458 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -60,7 +60,7 @@ _GLOBAL(call_do_softirq)
 	blr
 
 /*
- * void call_do_irq(struct pt_regs *regs, struct thread_info *irqtp);
+ * void call_do_irq(struct pt_regs *regs, void *sp);
  */
 _GLOBAL(call_do_irq)
 	mflr	r0
@@ -603,7 +603,7 @@ EXPORT_SYMBOL(__bswapdi2)
 #ifdef CONFIG_SMP
 _GLOBAL(start_secondary_resume)
 	/* Reset stack */
-	CURRENT_THREAD_INFO(r1, r1)
+	rlwinm	r1, r1, 0, 0, 31 - THREAD_SHIFT
 	addi	r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD
 	li	r3,0
 	stw	r3,0(r1)		/* Zero the stack frame pointer	*/
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index d9d4eb2ea6c9..a12307ebb7ef 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1237,8 +1237,8 @@ struct task_struct *__switch_to(struct task_struct *prev,
 		batch->active = 1;
 	}
 
-	if (current_thread_info()->task->thread.regs) {
-		restore_math(current_thread_info()->task->thread.regs);
+	if (current->thread.regs) {
+		restore_math(current->thread.regs);
 
 		/*
 		 * The copy-paste buffer can only store into foreign real
@@ -1248,7 +1248,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
 		 * mappings, we must issue a cp_abort to clear any state and
 		 * prevent snooping, corruption or a covert channel.
 		 */
-		if (current_thread_info()->task->thread.used_vas)
+		if (current->thread.used_vas)
 			asm volatile(PPC_CP_ABORT);
 	}
 #endif /* CONFIG_PPC_BOOK3S_64 */
@@ -1632,7 +1632,7 @@ 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);
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 9ca9db707bcb..8054a7b9e026 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -940,7 +940,7 @@ 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;
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 8c507be12c3c..81ebf7d6f526 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -205,10 +205,8 @@ void __init irqstack_early_init(void)
 	/* interrupt stacks must be in lowmem, we get that for free on ppc32
 	 * as the memblock is limited to lowmem by default */
 	for_each_possible_cpu(i) {
-		softirq_ctx[i] = (struct thread_info *)
-			__va(memblock_alloc(THREAD_SIZE, THREAD_SIZE));
-		hardirq_ctx[i] = (struct thread_info *)
-			__va(memblock_alloc(THREAD_SIZE, THREAD_SIZE));
+		softirq_ctx[i] = __va(memblock_alloc(THREAD_SIZE, THREAD_SIZE));
+		hardirq_ctx[i] = __va(memblock_alloc(THREAD_SIZE, THREAD_SIZE));
 	}
 }
 
@@ -226,13 +224,10 @@ void __init exc_lvl_early_init(void)
 		hw_cpu = 0;
 #endif
 
-		critirq_ctx[hw_cpu] = (struct thread_info *)
-			__va(memblock_alloc(THREAD_SIZE, THREAD_SIZE));
+		critirq_ctx[hw_cpu] = __va(memblock_alloc(THREAD_SIZE, THREAD_SIZE));
 #ifdef CONFIG_BOOKE
-		dbgirq_ctx[hw_cpu] = (struct thread_info *)
-			__va(memblock_alloc(THREAD_SIZE, THREAD_SIZE));
-		mcheckirq_ctx[hw_cpu] = (struct thread_info *)
-			__va(memblock_alloc(THREAD_SIZE, THREAD_SIZE));
+		dbgirq_ctx[hw_cpu] = __va(memblock_alloc(THREAD_SIZE, THREAD_SIZE));
+		mcheckirq_ctx[hw_cpu] = __va(memblock_alloc(THREAD_SIZE, THREAD_SIZE));
 #endif
 	}
 }
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 61c1fadbc644..19dd0ea55714 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -20,6 +20,7 @@
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/sched/mm.h>
+#include <linux/sched/task_stack.h>
 #include <linux/sched/topology.h>
 #include <linux/smp.h>
 #include <linux/interrupt.h>
@@ -812,7 +813,8 @@ static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle)
 
 #ifdef CONFIG_PPC64
 	paca_ptrs[cpu]->__current = idle;
-	paca_ptrs[cpu]->kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD;
+	paca_ptrs[cpu]->kstack = (unsigned long)task_stack_page(idle) +
+				  THREAD_SIZE - STACK_FRAME_OVERHEAD;
 #endif
 	ti->cpu = cpu;
 	secondary_ti = current_set[cpu] = ti;
-- 
2.13.3

[PATCH v6 4/9] powerpc: Activate CONFIG_THREAD_INFO_IN_TASK

[Christophe Leroy]

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.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/Kconfig                   |  1 +
 arch/powerpc/Makefile                  |  8 +++++-
 arch/powerpc/include/asm/ptrace.h      |  2 +-
 arch/powerpc/include/asm/smp.h         | 17 +++++++++++-
 arch/powerpc/include/asm/thread_info.h | 17 ++----------
 arch/powerpc/kernel/asm-offsets.c      |  7 +++--
 arch/powerpc/kernel/entry_32.S         |  9 +++----
 arch/powerpc/kernel/exceptions-64e.S   | 11 --------
 arch/powerpc/kernel/head_32.S          |  6 ++---
 arch/powerpc/kernel/head_44x.S         |  4 +--
 arch/powerpc/kernel/head_64.S          |  1 +
 arch/powerpc/kernel/head_booke.h       |  8 +-----
 arch/powerpc/kernel/head_fsl_booke.S   |  7 +++--
 arch/powerpc/kernel/irq.c              | 47 +---------------------------------
 arch/powerpc/kernel/kgdb.c             | 28 --------------------
 arch/powerpc/kernel/machine_kexec_64.c |  6 ++---
 arch/powerpc/kernel/setup_64.c         | 21 ---------------
 arch/powerpc/kernel/smp.c              |  2 +-
 arch/powerpc/net/bpf_jit32.h           |  5 ++--
 19 files changed, 52 insertions(+), 155 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 602eea723624..3b958cd4e284 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -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.
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 81552c7b46eb..02e7ca1c15d4 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -422,6 +422,13 @@ 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
+
 # Use the file '.tmp_gas_check' for binutils tests, as gas won't output
 # to stdout and these checks are run even on install targets.
 TOUT	:= .tmp_gas_check
@@ -439,4 +446,3 @@ checkbin:
 
 
 CLEAN_FILES += $(TOUT)
-
diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 447cbd1bee99..3a7e5561630b 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -120,7 +120,7 @@ extern int ptrace_put_reg(struct task_struct *task, int regno,
 			  unsigned long data);
 
 #define current_pt_regs() \
-	((struct pt_regs *)((unsigned long)current_thread_info() + THREAD_SIZE) - 1)
+	((struct pt_regs *)((unsigned long)task_stack_page(current) + THREAD_SIZE) - 1)
 /*
  * We use the least-significant bit of the trap field to indicate
  * whether we have saved the full set of registers, or only a
diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index 95b66a0c639b..93a8cd120663 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -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)
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 3185f8ac1182..61c8747cd926 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -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__
@@ -33,8 +33,6 @@
  * 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 */
@@ -53,8 +51,6 @@ struct thread_info {
  */
 #define INIT_THREAD_INFO(tsk)			\
 {						\
-	.task =		&tsk,			\
-	.cpu =		0,			\
 	.preempt_count = INIT_PREEMPT_COUNT,	\
 	.flags =	0,			\
 }
@@ -62,15 +58,6 @@ 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);
 #endif /* __ASSEMBLY__ */
 
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index c583a02e5a21..833d189df04c 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -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>
@@ -95,6 +97,9 @@ int main(void)
 	OFFSET(KSP_LIMIT, thread_struct, ksp_limit);
 #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);
@@ -162,8 +167,6 @@ 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);
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 7ea1d71f4546..fa7a69ffb37a 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -1166,10 +1166,6 @@ 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;
@@ -1292,10 +1288,13 @@ 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 */
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 6d6e144a28ce..231d066b4a3d 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -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.
diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index dce6f2ff07e5..44dfd73b2a62 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -844,9 +844,9 @@ __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
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index 15d39b2499de..2c7e90f36358 100644
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -1022,8 +1022,8 @@ _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
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 4898e9491a1c..c6a9bf7b34bf 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -805,6 +805,7 @@ __secondary_start:
 	LOAD_REG_ADDR(r3, current_set)
 	sldi	r28,r24,3		/* get current_set[cpu#]	 */
 	ldx	r14,r3,r28
+	ld	r14,TASK_STACK(r14)
 	addi	r14,r14,THREAD_SIZE-STACK_FRAME_OVERHEAD
 	std	r14,PACAKSAVE(r13)
 
diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h
index 175f812066dc..f0c254ab9703 100644
--- a/arch/powerpc/kernel/head_booke.h
+++ b/arch/powerpc/kernel/head_booke.h
@@ -143,13 +143,7 @@
 	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;							     \
diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index 239ad8a4754e..b8a2b789677e 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -704,8 +704,7 @@ 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
@@ -1078,8 +1077,8 @@ __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
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 9e7dc4468c8c..3fdb6b6973cf 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -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);
 }
 
@@ -711,7 +696,6 @@ 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) {
@@ -726,20 +710,9 @@ void exc_lvl_ctx_init(void)
 #endif
 
 		memset((void *)critirq_ctx[cpu_nr], 0, THREAD_SIZE);
-		tp = critirq_ctx[cpu_nr];
-		tp->cpu = cpu_nr;
-		tp->preempt_count = 0;
-
 #ifdef CONFIG_BOOKE
 		memset((void *)dbgirq_ctx[cpu_nr], 0, THREAD_SIZE);
-		tp = dbgirq_ctx[cpu_nr];
-		tp->cpu = cpu_nr;
-		tp->preempt_count = 0;
-
 		memset((void *)mcheckirq_ctx[cpu_nr], 0, THREAD_SIZE);
-		tp = mcheckirq_ctx[cpu_nr];
-		tp->cpu = cpu_nr;
-		tp->preempt_count = HARDIRQ_OFFSET;
 #endif
 	}
 }
@@ -750,38 +723,20 @@ 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) {
 		memset((void *)softirq_ctx[i], 0, THREAD_SIZE);
-		tp = softirq_ctx[i];
-		tp->cpu = i;
-		klp_init_thread_info(tp);
-
 		memset((void *)hardirq_ctx[i], 0, THREAD_SIZE);
-		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)
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index 59c578f865aa..5056e54b5239 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c
@@ -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;
 }
 
diff --git a/arch/powerpc/kernel/machine_kexec_64.c b/arch/powerpc/kernel/machine_kexec_64.c
index a0f6f45005bd..75692c327ba0 100644
--- a/arch/powerpc/kernel/machine_kexec_64.c
+++ b/arch/powerpc/kernel/machine_kexec_64.c
@@ -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
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index faf00222b324..2d682f3e31c6 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -691,24 +691,6 @@ 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
  * stack for machine checks.
@@ -739,20 +721,17 @@ void __init emergency_stack_init(void)
 
 		ti = alloc_stack(limit, i);
 		memset(ti, 0, THREAD_SIZE);
-		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);
 		memset(ti, 0, THREAD_SIZE);
-		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);
 		memset(ti, 0, THREAD_SIZE);
-		emerg_stack_init_thread_info(ti, i);
 		paca_ptrs[i]->mc_emergency_sp = (void *)ti + THREAD_SIZE;
 #endif
 	}
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 19dd0ea55714..f22fcbeb9898 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -816,7 +816,7 @@ 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;
 }
 
diff --git a/arch/powerpc/net/bpf_jit32.h b/arch/powerpc/net/bpf_jit32.h
index 6f4daacad296..dc50a8d4b3b9 100644
--- a/arch/powerpc/net/bpf_jit32.h
+++ b/arch/powerpc/net/bpf_jit32.h
@@ -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
-- 
2.13.3

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

[Christophe Leroy]

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@c-s.fr>
---
 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

[PATCH v6 6/9] powerpc: 'current_set' is now a table of task_struct pointers

[Christophe Leroy]

The table of pointers 'current_set' has been used for retrieving
the stack and current. They used to be thread_info pointers as
they were pointing to the stack and current was taken from the
'task' field of the thread_info.

Now, the pointers of 'current_set' table are now both pointers
to task_struct and pointers to thread_info.

As they are used to get current, and the stack pointer is
retrieved from current's stack field, this patch changes
their type to task_struct, and renames secondary_ti to
secondary_current.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/include/asm/asm-prototypes.h |  4 ++--
 arch/powerpc/kernel/head_32.S             |  6 +++---
 arch/powerpc/kernel/head_44x.S            |  4 ++--
 arch/powerpc/kernel/head_fsl_booke.S      |  4 ++--
 arch/powerpc/kernel/smp.c                 | 10 ++++------
 5 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/include/asm/asm-prototypes.h b/arch/powerpc/include/asm/asm-prototypes.h
index 9bc98c239305..ab0541f9da42 100644
--- a/arch/powerpc/include/asm/asm-prototypes.h
+++ b/arch/powerpc/include/asm/asm-prototypes.h
@@ -23,8 +23,8 @@
 #include <uapi/asm/ucontext.h>
 
 /* SMP */
-extern struct thread_info *current_set[NR_CPUS];
-extern struct thread_info *secondary_ti;
+extern struct task_struct *current_set[NR_CPUS];
+extern struct task_struct *secondary_current;
 void start_secondary(void *unused);
 
 /* kexec */
diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 44dfd73b2a62..ba0341bd5a00 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -842,9 +842,9 @@ __secondary_start:
 #endif /* CONFIG_6xx */
 
 	/* get current's stack and current */
-	lis	r1,secondary_ti@ha
-	tophys(r1,r1)
-	lwz	r2,secondary_ti@l(r1)
+	lis	r2,secondary_current@ha
+	tophys(r2,r2)
+	lwz	r2,secondary_current@l(r2)
 	tophys(r1,r2)
 	lwz	r1,TASK_STACK(r1)
 
diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index 2c7e90f36358..48e4de4dfd0c 100644
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -1021,8 +1021,8 @@ _GLOBAL(start_secondary_47x)
 	/* Now we can get our task struct and real stack pointer */
 
 	/* Get current's stack and current */
-	lis	r1,secondary_ti@ha
-	lwz	r2,secondary_ti@l(r1)
+	lis	r2,secondary_current@ha
+	lwz	r2,secondary_current@l(r2)
 	lwz	r1,TASK_STACK(r2)
 
 	/* Current stack pointer */
diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index b8a2b789677e..0d27bfff52dd 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -1076,8 +1076,8 @@ __secondary_start:
 	bl	call_setup_cpu
 
 	/* get current's stack and current */
-	lis	r1,secondary_ti@ha
-	lwz	r2,secondary_ti@l(r1)
+	lis	r2,secondary_current@ha
+	lwz	r2,secondary_current@l(r2)
 	lwz	r1,TASK_STACK(r2)
 
 	/* stack */
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index f22fcbeb9898..00193643f0da 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -74,7 +74,7 @@
 static DEFINE_PER_CPU(int, cpu_state) = { 0 };
 #endif
 
-struct thread_info *secondary_ti;
+struct task_struct *secondary_current;
 
 DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
 DEFINE_PER_CPU(cpumask_var_t, cpu_l2_cache_map);
@@ -644,7 +644,7 @@ void smp_send_stop(void)
 }
 #endif /* CONFIG_NMI_IPI */
 
-struct thread_info *current_set[NR_CPUS];
+struct task_struct *current_set[NR_CPUS];
 
 static void smp_store_cpu_info(int id)
 {
@@ -724,7 +724,7 @@ void smp_prepare_boot_cpu(void)
 	paca_ptrs[boot_cpuid]->__current = current;
 #endif
 	set_numa_node(numa_cpu_lookup_table[boot_cpuid]);
-	current_set[boot_cpuid] = task_thread_info(current);
+	current_set[boot_cpuid] = current;
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -809,15 +809,13 @@ static bool secondaries_inhibited(void)
 
 static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle)
 {
-	struct thread_info *ti = task_thread_info(idle);
-
 #ifdef CONFIG_PPC64
 	paca_ptrs[cpu]->__current = idle;
 	paca_ptrs[cpu]->kstack = (unsigned long)task_stack_page(idle) +
 				  THREAD_SIZE - STACK_FRAME_OVERHEAD;
 #endif
 	idle->cpu = cpu;
-	secondary_ti = current_set[cpu] = ti;
+	secondary_current = current_set[cpu] = idle;
 }
 
 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
-- 
2.13.3

[PATCH v6 7/9] powerpc/32: Remove CURRENT_THREAD_INFO and rename TI_CPU

[Christophe Leroy]

Now that thread_info is similar to task_struct, it's address is in r2
so CURRENT_THREAD_INFO() macro is useless. This patch removes it.

At the same time, as the 'cpu' field is not anymore in thread_info,
this patch renames it to TASK_CPU.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/Makefile                  |  2 +-
 arch/powerpc/include/asm/thread_info.h |  2 --
 arch/powerpc/kernel/asm-offsets.c      |  2 +-
 arch/powerpc/kernel/entry_32.S         | 43 ++++++++++++----------------------
 arch/powerpc/kernel/epapr_hcalls.S     |  5 ++--
 arch/powerpc/kernel/head_fsl_booke.S   |  5 ++--
 arch/powerpc/kernel/idle_6xx.S         |  8 +++----
 arch/powerpc/kernel/idle_e500.S        |  8 +++----
 arch/powerpc/kernel/misc_32.S          |  3 +--
 arch/powerpc/mm/hash_low_32.S          | 14 ++++-------
 arch/powerpc/sysdev/6xx-suspend.S      |  5 ++--
 11 files changed, 35 insertions(+), 62 deletions(-)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 02e7ca1c15d4..f1e2d7f7b022 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -426,7 +426,7 @@ 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))
+       $(eval KBUILD_CFLAGS += -D_TASK_CPU=$(shell awk '{if ($$2 == "TASK_CPU") print $$3;}' include/generated/asm-offsets.h))
 endif
 
 # Use the file '.tmp_gas_check' for binutils tests, as gas won't output
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 61c8747cd926..361bb45b8990 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -19,8 +19,6 @@
 
 #ifdef CONFIG_PPC64
 #define CURRENT_THREAD_INFO(dest, sp)	stringify_in_c(ld dest, PACACURRENT(r13))
-#else
-#define CURRENT_THREAD_INFO(dest, sp)	stringify_in_c(mr dest, r2)
 #endif
 
 #ifndef __ASSEMBLY__
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 768ce602d624..31be6eb9c0d4 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -97,7 +97,7 @@ int main(void)
 #endif /* CONFIG_PPC64 */
 	OFFSET(TASK_STACK, task_struct, stack);
 #ifdef CONFIG_SMP
-	OFFSET(TI_CPU, task_struct, cpu);
+	OFFSET(TASK_CPU, task_struct, cpu);
 #endif
 
 #ifdef CONFIG_LIVEPATCH
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index bd3b146e18a3..d0c546ce387e 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -168,8 +168,7 @@ transfer_to_handler:
 	tophys(r11,r11)
 	addi	r11,r11,global_dbcr0@l
 #ifdef CONFIG_SMP
-	CURRENT_THREAD_INFO(r9, r1)
-	lwz	r9,TI_CPU(r9)
+	lwz	r9,TASK_CPU(r2)
 	slwi	r9,r9,3
 	add	r11,r11,r9
 #endif
@@ -180,8 +179,7 @@ transfer_to_handler:
 	stw	r12,4(r11)
 #endif
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
-	CURRENT_THREAD_INFO(r9, r1)
-	tophys(r9, r9)
+	tophys(r9, r2)
 	ACCOUNT_CPU_USER_ENTRY(r9, r11, r12)
 #endif
 
@@ -195,8 +193,7 @@ transfer_to_handler:
 	ble-	stack_ovf		/* then the kernel stack overflowed */
 5:
 #if defined(CONFIG_6xx) || defined(CONFIG_E500)
-	CURRENT_THREAD_INFO(r9, r1)
-	tophys(r9,r9)			/* check local flags */
+	tophys(r9,r2)			/* check local flags */
 	lwz	r12,TI_LOCAL_FLAGS(r9)
 	mtcrf	0x01,r12
 	bt-	31-TLF_NAPPING,4f
@@ -345,8 +342,7 @@ _GLOBAL(DoSyscall)
 	mtmsr	r11
 1:
 #endif /* CONFIG_TRACE_IRQFLAGS */
-	CURRENT_THREAD_INFO(r10, r1)
-	lwz	r11,TI_FLAGS(r10)
+	lwz	r11,TI_FLAGS(r2)
 	andi.	r11,r11,_TIF_SYSCALL_DOTRACE
 	bne-	syscall_dotrace
 syscall_dotrace_cont:
@@ -379,13 +375,12 @@ ret_from_syscall:
 	lwz	r3,GPR3(r1)
 #endif
 	mr	r6,r3
-	CURRENT_THREAD_INFO(r12, r1)
 	/* disable interrupts so current_thread_info()->flags can't change */
 	LOAD_MSR_KERNEL(r10,MSR_KERNEL)	/* doesn't include MSR_EE */
 	/* Note: We don't bother telling lockdep about it */
 	SYNC
 	MTMSRD(r10)
-	lwz	r9,TI_FLAGS(r12)
+	lwz	r9,TI_FLAGS(r2)
 	li	r8,-MAX_ERRNO
 	andi.	r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
 	bne-	syscall_exit_work
@@ -432,8 +427,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 	andi.	r4,r8,MSR_PR
 	beq	3f
-	CURRENT_THREAD_INFO(r4, r1)
-	ACCOUNT_CPU_USER_EXIT(r4, r5, r7)
+	ACCOUNT_CPU_USER_EXIT(r2, r5, r7)
 3:
 #endif
 	lwz	r4,_LINK(r1)
@@ -526,7 +520,7 @@ syscall_exit_work:
 	/* Clear per-syscall TIF flags if any are set.  */
 
 	li	r11,_TIF_PERSYSCALL_MASK
-	addi	r12,r12,TI_FLAGS
+	addi	r12,r2,TI_FLAGS
 3:	lwarx	r8,0,r12
 	andc	r8,r8,r11
 #ifdef CONFIG_IBM405_ERR77
@@ -534,7 +528,6 @@ syscall_exit_work:
 #endif
 	stwcx.	r8,0,r12
 	bne-	3b
-	subi	r12,r12,TI_FLAGS
 	
 4:	/* Anything which requires enabling interrupts? */
 	andi.	r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP)
@@ -813,8 +806,7 @@ ret_from_except:
 
 user_exc_return:		/* r10 contains MSR_KERNEL here */
 	/* Check current_thread_info()->flags */
-	CURRENT_THREAD_INFO(r9, r1)
-	lwz	r9,TI_FLAGS(r9)
+	lwz	r9,TI_FLAGS(r2)
 	andi.	r0,r9,_TIF_USER_WORK_MASK
 	bne	do_work
 
@@ -827,8 +819,7 @@ restore_user:
 	bnel-	load_dbcr0
 #endif
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
-	CURRENT_THREAD_INFO(r9, r1)
-	ACCOUNT_CPU_USER_EXIT(r9, r10, r11)
+	ACCOUNT_CPU_USER_EXIT(r2, r10, r11)
 #endif
 
 	b	restore
@@ -836,8 +827,7 @@ restore_user:
 /* N.B. the only way to get here is from the beq following ret_from_except. */
 resume_kernel:
 	/* check current_thread_info, _TIF_EMULATE_STACK_STORE */
-	CURRENT_THREAD_INFO(r9, r1)
-	lwz	r8,TI_FLAGS(r9)
+	lwz	r8,TI_FLAGS(r2)
 	andis.	r0,r8,_TIF_EMULATE_STACK_STORE@h
 	beq+	1f
 
@@ -863,7 +853,7 @@ resume_kernel:
 
 	/* Clear _TIF_EMULATE_STACK_STORE flag */
 	lis	r11,_TIF_EMULATE_STACK_STORE@h
-	addi	r5,r9,TI_FLAGS
+	addi	r5,r2,TI_FLAGS
 0:	lwarx	r8,0,r5
 	andc	r8,r8,r11
 #ifdef CONFIG_IBM405_ERR77
@@ -875,7 +865,7 @@ resume_kernel:
 
 #ifdef CONFIG_PREEMPT
 	/* check current_thread_info->preempt_count */
-	lwz	r0,TI_PREEMPT(r9)
+	lwz	r0,TI_PREEMPT(r2)
 	cmpwi	0,r0,0		/* if non-zero, just restore regs and return */
 	bne	restore
 	andi.	r8,r8,_TIF_NEED_RESCHED
@@ -891,8 +881,7 @@ resume_kernel:
 	bl	trace_hardirqs_off
 #endif
 1:	bl	preempt_schedule_irq
-	CURRENT_THREAD_INFO(r9, r1)
-	lwz	r3,TI_FLAGS(r9)
+	lwz	r3,TI_FLAGS(r2)
 	andi.	r0,r3,_TIF_NEED_RESCHED
 	bne-	1b
 #ifdef CONFIG_TRACE_IRQFLAGS
@@ -1191,8 +1180,7 @@ load_dbcr0:
 	lis	r11,global_dbcr0@ha
 	addi	r11,r11,global_dbcr0@l
 #ifdef CONFIG_SMP
-	CURRENT_THREAD_INFO(r9, r1)
-	lwz	r9,TI_CPU(r9)
+	lwz	r9,TASK_CPU(r2)
 	slwi	r9,r9,3
 	add	r11,r11,r9
 #endif
@@ -1232,8 +1220,7 @@ recheck:
 	LOAD_MSR_KERNEL(r10,MSR_KERNEL)
 	SYNC
 	MTMSRD(r10)		/* disable interrupts */
-	CURRENT_THREAD_INFO(r9, r1)
-	lwz	r9,TI_FLAGS(r9)
+	lwz	r9,TI_FLAGS(r2)
 	andi.	r0,r9,_TIF_NEED_RESCHED
 	bne-	do_resched
 	andi.	r0,r9,_TIF_USER_WORK_MASK
diff --git a/arch/powerpc/kernel/epapr_hcalls.S b/arch/powerpc/kernel/epapr_hcalls.S
index 52ca2471ee1a..d252f4663a23 100644
--- a/arch/powerpc/kernel/epapr_hcalls.S
+++ b/arch/powerpc/kernel/epapr_hcalls.S
@@ -21,10 +21,9 @@
 #ifndef CONFIG_PPC64
 /* epapr_ev_idle() was derived from e500_idle() */
 _GLOBAL(epapr_ev_idle)
-	CURRENT_THREAD_INFO(r3, r1)
-	PPC_LL	r4, TI_LOCAL_FLAGS(r3)	/* set napping bit */
+	PPC_LL	r4, TI_LOCAL_FLAGS(r2)	/* set napping bit */
 	ori	r4, r4,_TLF_NAPPING	/* so when we take an exception */
-	PPC_STL	r4, TI_LOCAL_FLAGS(r3)	/* it will return to our caller */
+	PPC_STL	r4, TI_LOCAL_FLAGS(r2)	/* it will return to our caller */
 
 	wrteei	1
 
diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index 0d27bfff52dd..38918f82bc5b 100644
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -244,8 +244,7 @@ set_ivor:
 	stwu	r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
 
 #ifdef CONFIG_SMP
-	CURRENT_THREAD_INFO(r22, r1)
-	stw	r24, TI_CPU(r22)
+	stw	r24, TASK_CPU(r2)
 #endif
 
 	bl	early_init
@@ -704,7 +703,7 @@ finish_tlb_load:
 
 	/* Get the next_tlbcam_idx percpu var */
 #ifdef CONFIG_SMP
-	lwz	r15, TI_CPU-THREAD(r12)
+	lwz	r15, TASK_CPU-THREAD(r12)
 	lis     r14, __per_cpu_offset@h
 	ori     r14, r14, __per_cpu_offset@l
 	rlwinm  r15, r15, 2, 0, 29
diff --git a/arch/powerpc/kernel/idle_6xx.S b/arch/powerpc/kernel/idle_6xx.S
index ff026c9d3cab..5afd2e236990 100644
--- a/arch/powerpc/kernel/idle_6xx.S
+++ b/arch/powerpc/kernel/idle_6xx.S
@@ -136,10 +136,9 @@ BEGIN_FTR_SECTION
 	DSSALL
 	sync
 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
-	CURRENT_THREAD_INFO(r9, r1)
-	lwz	r8,TI_LOCAL_FLAGS(r9)	/* set napping bit */
+	lwz	r8,TI_LOCAL_FLAGS(r2)	/* set napping bit */
 	ori	r8,r8,_TLF_NAPPING	/* so when we take an exception */
-	stw	r8,TI_LOCAL_FLAGS(r9)	/* it will return to our caller */
+	stw	r8,TI_LOCAL_FLAGS(r2)	/* it will return to our caller */
 	mfmsr	r7
 	ori	r7,r7,MSR_EE
 	oris	r7,r7,MSR_POW@h
@@ -159,8 +158,7 @@ _GLOBAL(power_save_ppc32_restore)
 	stw	r9,_NIP(r11)		/* make it do a blr */
 
 #ifdef CONFIG_SMP
-	CURRENT_THREAD_INFO(r12, r11)
-	lwz	r11,TI_CPU(r12)		/* get cpu number * 4 */
+	lwz	r11,TASK_CPU(r2)		/* get cpu number * 4 */
 	slwi	r11,r11,2
 #else
 	li	r11,0
diff --git a/arch/powerpc/kernel/idle_e500.S b/arch/powerpc/kernel/idle_e500.S
index 583e55ac7d26..69dfcd2ca011 100644
--- a/arch/powerpc/kernel/idle_e500.S
+++ b/arch/powerpc/kernel/idle_e500.S
@@ -22,10 +22,9 @@
 	.text
 
 _GLOBAL(e500_idle)
-	CURRENT_THREAD_INFO(r3, r1)
-	lwz	r4,TI_LOCAL_FLAGS(r3)	/* set napping bit */
+	lwz	r4,TI_LOCAL_FLAGS(r2)	/* set napping bit */
 	ori	r4,r4,_TLF_NAPPING	/* so when we take an exception */
-	stw	r4,TI_LOCAL_FLAGS(r3)	/* it will return to our caller */
+	stw	r4,TI_LOCAL_FLAGS(r2)	/* it will return to our caller */
 
 #ifdef CONFIG_PPC_E500MC
 	wrteei	1
@@ -88,8 +87,7 @@ _GLOBAL(power_save_ppc32_restore)
 	stw	r9,_NIP(r11)		/* make it do a blr */
 
 #ifdef CONFIG_SMP
-	CURRENT_THREAD_INFO(r12, r1)
-	lwz	r11,TI_CPU(r12)		/* get cpu number * 4 */
+	lwz	r11,TASK_CPU(r2)		/* get cpu number * 4 */
 	slwi	r11,r11,2
 #else
 	li	r11,0
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index a3663ad62f16..0e4da0fe5cbf 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -183,8 +183,7 @@ _GLOBAL(low_choose_750fx_pll)
 
 #ifdef CONFIG_SMP
 	/* Store new HID1 image */
-	CURRENT_THREAD_INFO(r6, r1)
-	lwz	r6,TI_CPU(r6)
+	lwz	r6,TASK_CPU(r2)
 	slwi	r6,r6,2
 #else
 	li	r6, 0
diff --git a/arch/powerpc/mm/hash_low_32.S b/arch/powerpc/mm/hash_low_32.S
index 26acf6c8c20c..27edbfddebaa 100644
--- a/arch/powerpc/mm/hash_low_32.S
+++ b/arch/powerpc/mm/hash_low_32.S
@@ -185,8 +185,7 @@ _GLOBAL(add_hash_page)
 	add	r3,r3,r0		/* note create_hpte trims to 24 bits */
 
 #ifdef CONFIG_SMP
-	CURRENT_THREAD_INFO(r8, r1)	/* use cpu number to make tag */
-	lwz	r8,TI_CPU(r8)		/* to go in mmu_hash_lock */
+	lwz	r8,TASK_CPU(r2)		/* to go in mmu_hash_lock */
 	oris	r8,r8,12
 #endif /* CONFIG_SMP */
 
@@ -546,9 +545,8 @@ _GLOBAL(flush_hash_pages)
 #ifdef CONFIG_SMP
 	addis	r9,r7,mmu_hash_lock@ha
 	addi	r9,r9,mmu_hash_lock@l
-	CURRENT_THREAD_INFO(r8, r1)
-	add	r8,r8,r7
-	lwz	r8,TI_CPU(r8)
+	add	r8,r2,r7
+	lwz	r8,TASK_CPU(r8)
 	oris	r8,r8,9
 10:	lwarx	r0,0,r9
 	cmpi	0,r0,0
@@ -641,8 +639,7 @@ EXPORT_SYMBOL(flush_hash_pages)
  */
 _GLOBAL(_tlbie)
 #ifdef CONFIG_SMP
-	CURRENT_THREAD_INFO(r8, r1)
-	lwz	r8,TI_CPU(r8)
+	lwz	r8,TASK_CPU(r2)
 	oris	r8,r8,11
 	mfmsr	r10
 	SYNC
@@ -679,8 +676,7 @@ _GLOBAL(_tlbie)
  */
 _GLOBAL(_tlbia)
 #if defined(CONFIG_SMP)
-	CURRENT_THREAD_INFO(r8, r1)
-	lwz	r8,TI_CPU(r8)
+	lwz	r8,TASK_CPU(r2)
 	oris	r8,r8,10
 	mfmsr	r10
 	SYNC
diff --git a/arch/powerpc/sysdev/6xx-suspend.S b/arch/powerpc/sysdev/6xx-suspend.S
index cf48e9cb2575..6c4aec25c4ba 100644
--- a/arch/powerpc/sysdev/6xx-suspend.S
+++ b/arch/powerpc/sysdev/6xx-suspend.S
@@ -29,10 +29,9 @@ _GLOBAL(mpc6xx_enter_standby)
 	ori	r5, r5, ret_from_standby@l
 	mtlr	r5
 
-	CURRENT_THREAD_INFO(r5, r1)
-	lwz	r6, TI_LOCAL_FLAGS(r5)
+	lwz	r6, TI_LOCAL_FLAGS(r2)
 	ori	r6, r6, _TLF_SLEEPING
-	stw	r6, TI_LOCAL_FLAGS(r5)
+	stw	r6, TI_LOCAL_FLAGS(r2)
 
 	mfmsr	r5
 	ori	r5, r5, MSR_EE
-- 
2.13.3

[PATCH v6 8/9] powerpc/64: Remove CURRENT_THREAD_INFO

[Christophe Leroy]

Now that current_thread_info is located at the beginning of 'current'
task struct, CURRENT_THREAD_INFO macro is not really needed any more.

This patch replaces it by loads of the value at PACACURRENT(r13).

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/include/asm/exception-64s.h       |  4 ++--
 arch/powerpc/include/asm/thread_info.h         |  4 ----
 arch/powerpc/kernel/entry_64.S                 | 10 +++++-----
 arch/powerpc/kernel/exceptions-64e.S           |  2 +-
 arch/powerpc/kernel/exceptions-64s.S           |  2 +-
 arch/powerpc/kernel/idle_book3e.S              |  2 +-
 arch/powerpc/kernel/idle_power4.S              |  2 +-
 arch/powerpc/kernel/trace/ftrace_64_mprofile.S |  6 +++---
 8 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index a86feddddad0..ca3af3e9015e 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -680,7 +680,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
 
 #define RUNLATCH_ON				\
 BEGIN_FTR_SECTION				\
-	CURRENT_THREAD_INFO(r3, r1);		\
+	ld	r3, PACACURRENT(r13);		\
 	ld	r4,TI_LOCAL_FLAGS(r3);		\
 	andi.	r0,r4,_TLF_RUNLATCH;		\
 	beql	ppc64_runlatch_on_trampoline;	\
@@ -730,7 +730,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_CTRL)
 #ifdef CONFIG_PPC_970_NAP
 #define FINISH_NAP				\
 BEGIN_FTR_SECTION				\
-	CURRENT_THREAD_INFO(r11, r1);		\
+	ld	r11, PACACURRENT(r13);		\
 	ld	r9,TI_LOCAL_FLAGS(r11);		\
 	andi.	r10,r9,_TLF_NAPPING;		\
 	bnel	power4_fixup_nap;		\
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 361bb45b8990..2ee9e248c933 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -17,10 +17,6 @@
 
 #define THREAD_SIZE		(1 << THREAD_SHIFT)
 
-#ifdef CONFIG_PPC64
-#define CURRENT_THREAD_INFO(dest, sp)	stringify_in_c(ld dest, PACACURRENT(r13))
-#endif
-
 #ifndef __ASSEMBLY__
 #include <linux/cache.h>
 #include <asm/processor.h>
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 6fce0f8fd8c4..06d9a7c084a1 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -158,7 +158,7 @@ system_call:			/* label this so stack traces look sane */
 	li	r10,IRQS_ENABLED
 	std	r10,SOFTE(r1)
 
-	CURRENT_THREAD_INFO(r11, r1)
+	ld	r11, PACACURRENT(r13)
 	ld	r10,TI_FLAGS(r11)
 	andi.	r11,r10,_TIF_SYSCALL_DOTRACE
 	bne	.Lsyscall_dotrace		/* does not return */
@@ -205,7 +205,7 @@ system_call:			/* label this so stack traces look sane */
 	ld	r3,RESULT(r1)
 #endif
 
-	CURRENT_THREAD_INFO(r12, r1)
+	ld	r12, PACACURRENT(r13)
 
 	ld	r8,_MSR(r1)
 #ifdef CONFIG_PPC_BOOK3S
@@ -336,7 +336,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 
 	/* Repopulate r9 and r10 for the syscall path */
 	addi	r9,r1,STACK_FRAME_OVERHEAD
-	CURRENT_THREAD_INFO(r10, r1)
+	ld	r10, PACACURRENT(r13)
 	ld	r10,TI_FLAGS(r10)
 
 	cmpldi	r0,NR_syscalls
@@ -735,7 +735,7 @@ _GLOBAL(ret_from_except_lite)
 	mtmsrd	r10,1		  /* Update machine state */
 #endif /* CONFIG_PPC_BOOK3E */
 
-	CURRENT_THREAD_INFO(r9, r1)
+	ld	r9, PACACURRENT(r13)
 	ld	r3,_MSR(r1)
 #ifdef CONFIG_PPC_BOOK3E
 	ld	r10,PACACURRENT(r13)
@@ -849,7 +849,7 @@ resume_kernel:
 1:	bl	preempt_schedule_irq
 
 	/* Re-test flags and eventually loop */
-	CURRENT_THREAD_INFO(r9, r1)
+	ld	r9, PACACURRENT(r13)
 	ld	r4,TI_FLAGS(r9)
 	andi.	r0,r4,_TIF_NEED_RESCHED
 	bne	1b
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 231d066b4a3d..dfafcd0af009 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -469,7 +469,7 @@ exc_##n##_bad_stack:							    \
  * interrupts happen before the wait instruction.
  */
 #define CHECK_NAPPING()							\
-	CURRENT_THREAD_INFO(r11, r1);					\
+	ld	r11, PACACURRENT(r13);					\
 	ld	r10,TI_LOCAL_FLAGS(r11);				\
 	andi.	r9,r10,_TLF_NAPPING;					\
 	beq+	1f;							\
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index b9239dbf6d59..f776f30ecfcc 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1738,7 +1738,7 @@ do_hash_page:
 	ori	r0,r0,DSISR_BAD_FAULT_64S@l
 	and.	r0,r4,r0		/* weird error? */
 	bne-	handle_page_fault	/* if not, try to insert a HPTE */
-	CURRENT_THREAD_INFO(r11, r1)
+	ld	r11, PACACURRENT(r13)
 	lwz	r0,TI_PREEMPT(r11)	/* If we're in an "NMI" */
 	andis.	r0,r0,NMI_MASK@h	/* (i.e. an irq when soft-disabled) */
 	bne	77f			/* then don't call hash_page now */
diff --git a/arch/powerpc/kernel/idle_book3e.S b/arch/powerpc/kernel/idle_book3e.S
index 4e0d94d02030..31e732c378ad 100644
--- a/arch/powerpc/kernel/idle_book3e.S
+++ b/arch/powerpc/kernel/idle_book3e.S
@@ -63,7 +63,7 @@ _GLOBAL(\name)
 1:	/* Let's set the _TLF_NAPPING flag so interrupts make us return
 	 * to the right spot
 	*/
-	CURRENT_THREAD_INFO(r11, r1)
+	ld	r11, PACACURRENT(r13)
 	ld	r10,TI_LOCAL_FLAGS(r11)
 	ori	r10,r10,_TLF_NAPPING
 	std	r10,TI_LOCAL_FLAGS(r11)
diff --git a/arch/powerpc/kernel/idle_power4.S b/arch/powerpc/kernel/idle_power4.S
index a09b3c7ca176..61ac89fd0a05 100644
--- a/arch/powerpc/kernel/idle_power4.S
+++ b/arch/powerpc/kernel/idle_power4.S
@@ -68,7 +68,7 @@ BEGIN_FTR_SECTION
 	DSSALL
 	sync
 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
-	CURRENT_THREAD_INFO(r9, r1)
+	ld	r9, PACACURRENT(r13)
 	ld	r8,TI_LOCAL_FLAGS(r9)	/* set napping bit */
 	ori	r8,r8,_TLF_NAPPING	/* so when we take an exception */
 	std	r8,TI_LOCAL_FLAGS(r9)	/* it will return to our caller */
diff --git a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
index 32476a6e4e9c..202bec086e3b 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
+++ b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
@@ -229,7 +229,7 @@ ftrace_call:
 	 *  - r0, r11 & r12 are free
 	 */
 livepatch_handler:
-	CURRENT_THREAD_INFO(r12, r1)
+	ld	r12, PACACURRENT(r13)
 
 	/* Allocate 3 x 8 bytes */
 	ld	r11, TI_livepatch_sp(r12)
@@ -256,7 +256,7 @@ livepatch_handler:
 	 * restore it.
 	 */
 
-	CURRENT_THREAD_INFO(r12, r1)
+	ld	r12, PACACURRENT(r13)
 
 	ld	r11, TI_livepatch_sp(r12)
 
@@ -273,7 +273,7 @@ livepatch_handler:
 	ld	r2,  -24(r11)
 
 	/* Pop livepatch stack frame */
-	CURRENT_THREAD_INFO(r12, r1)
+	ld	r12, PACACURRENT(r13)
 	subi	r11, r11, 24
 	std	r11, TI_livepatch_sp(r12)
 
-- 
2.13.3

[PATCH v6 9/9] powerpc: clean stack pointers naming

[Christophe Leroy]

Some stack pointers used to also be thread_info pointers
and were called tp. Now that they are only stack pointers,
rename them sp.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/kernel/irq.c      | 17 +++++++----------
 arch/powerpc/kernel/setup_64.c | 20 ++++++++++----------
 2 files changed, 17 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 62cfccf4af89..754f0efc507b 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -659,21 +659,21 @@ void __do_irq(struct pt_regs *regs)
 void do_IRQ(struct pt_regs *regs)
 {
 	struct pt_regs *old_regs = set_irq_regs(regs);
-	void *curtp, *irqtp, *sirqtp;
+	void *cursp, *irqsp, *sirqsp;
 
 	/* Switch to the irq stack to handle this */
-	curtp = (void *)(current_stack_pointer() & ~(THREAD_SIZE - 1));
-	irqtp = hardirq_ctx[raw_smp_processor_id()];
-	sirqtp = softirq_ctx[raw_smp_processor_id()];
+	cursp = (void *)(current_stack_pointer() & ~(THREAD_SIZE - 1));
+	irqsp = hardirq_ctx[raw_smp_processor_id()];
+	sirqsp = softirq_ctx[raw_smp_processor_id()];
 
 	/* Already there ? */
-	if (unlikely(curtp == irqtp || curtp == sirqtp)) {
+	if (unlikely(cursp == irqsp || cursp == sirqsp)) {
 		__do_irq(regs);
 		set_irq_regs(old_regs);
 		return;
 	}
 	/* Switch stack and call */
-	call_do_irq(regs, irqtp);
+	call_do_irq(regs, irqsp);
 
 	set_irq_regs(old_regs);
 }
@@ -732,10 +732,7 @@ void irq_ctx_init(void)
 
 void do_softirq_own_stack(void)
 {
-	void *irqtp;
-
-	irqtp = softirq_ctx[smp_processor_id()];
-	call_do_softirq(irqtp);
+	call_do_softirq(softirq_ctx[smp_processor_id()]);
 }
 
 irq_hw_number_t virq_to_hw(unsigned int virq)
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 6792e9c90689..4912ec0320b8 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) {
-		void *ti;
+		void *sp;
 
-		ti = alloc_stack(limit, i);
-		memset(ti, 0, THREAD_SIZE);
-		paca_ptrs[i]->emergency_sp = ti + THREAD_SIZE;
+		sp = alloc_stack(limit, i);
+		memset(sp, 0, THREAD_SIZE);
+		paca_ptrs[i]->emergency_sp = sp + 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 = ti + THREAD_SIZE;
+		sp = alloc_stack(limit, i);
+		memset(sp, 0, THREAD_SIZE);
+		paca_ptrs[i]->nmi_emergency_sp = sp + 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 = ti + THREAD_SIZE;
+		sp = alloc_stack(limit, i);
+		memset(sp, 0, THREAD_SIZE);
+		paca_ptrs[i]->mc_emergency_sp = sp + THREAD_SIZE;
 #endif
 	}
 }
-- 
2.13.3

Re: [PATCH v6 0/9] powerpc: Switch to CONFIG_THREAD_INFO_IN_TASK

[Benjamin Herrenschmidt]

On Mon, 2018-10-08 at 09:16 +0000, Christophe Leroy wrote:
> The purpose of this serie is to activate CONFIG_THREAD_INFO_IN_TASK which
> moves the thread_info into task_struct.

We need to make sure we don't have code that assumes that we don't take
faults on TI access.

On ppc64, the stack SLB entries are bolted, which means the TI is too.

We might have code that assumes that we don't get SLB faults when
accessing TI. If not, we're fine but that needs a close look.

Ben.

> 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.
> 
> Changes since v5:
>  - Fixed livepatch_sp setup by using end_of_stack() instead of hardcoding
>  - Fixed PPC_BPF_LOAD_CPU() macro
> 
> Changes since v4:
>  - Fixed a build failure on 32bits SMP when include/generated/asm-offsets.h is not
>  already existing, was due to spaces instead of a tab in the Makefile
> 
> Changes since RFC v3: (based on Nick's review)
>  - Renamed task_size.h to task_size_user64.h to better relate to what it contains.
>  - Handling of the isolation of thread_info cpu field inside CONFIG_SMP #ifdefs moved to a separate patch.
>  - Removed CURRENT_THREAD_INFO macro completely.
>  - Added a guard in asm/smp.h to avoid build failure before _TASK_CPU is defined.
>  - Added a patch at the end to rename 'tp' pointers to 'sp' pointers
>  - Renamed 'tp' into 'sp' pointers in preparation patch when relevant
>  - Fixed a few commit logs
>  - Fixed checkpatch report.
> 
> Changes since RFC v2:
>  - Removed the modification of names in asm-offsets
>  - Created a rule in arch/powerpc/Makefile to append the offset of current->cpu in CFLAGS
>  - Modified asm/smp.h to use the offset set in CFLAGS
>  - Squashed the renaming of THREAD_INFO to TASK_STACK in the preparation patch
>  - Moved the modification of current_pt_regs in the patch activating CONFIG_THREAD_INFO_IN_TASK
> 
> Changes since RFC v1:
>  - Removed the first patch which was modifying header inclusion order in timer
>  - Modified some names in asm-offsets to avoid conflicts when including asm-offsets in C files
>  - Modified asm/smp.h to avoid having to include linux/sched.h (using asm-offsets instead)
>  - Moved some changes from the activation patch to the preparation patch.
> 
> Christophe Leroy (9):
>   book3s/64: avoid circular header inclusion in mmu-hash.h
>   powerpc: Only use task_struct 'cpu' field on SMP
>   powerpc: Prepare for moving thread_info into task_struct
>   powerpc: Activate CONFIG_THREAD_INFO_IN_TASK
>   powerpc: regain entire stack space
>   powerpc: 'current_set' is now a table of task_struct pointers
>   powerpc/32: Remove CURRENT_THREAD_INFO and rename TI_CPU
>   powerpc/64: Remove CURRENT_THREAD_INFO
>   powerpc: clean stack pointers naming
> 
>  arch/powerpc/Kconfig                           |  1 +
>  arch/powerpc/Makefile                          |  8 ++-
>  arch/powerpc/include/asm/asm-prototypes.h      |  4 +-
>  arch/powerpc/include/asm/book3s/64/mmu-hash.h  |  2 +-
>  arch/powerpc/include/asm/exception-64s.h       |  4 +-
>  arch/powerpc/include/asm/irq.h                 | 14 ++---
>  arch/powerpc/include/asm/livepatch.h           |  7 ++-
>  arch/powerpc/include/asm/processor.h           | 39 +------------
>  arch/powerpc/include/asm/ptrace.h              |  2 +-
>  arch/powerpc/include/asm/reg.h                 |  2 +-
>  arch/powerpc/include/asm/smp.h                 | 17 +++++-
>  arch/powerpc/include/asm/task_size_user64.h    | 42 ++++++++++++++
>  arch/powerpc/include/asm/thread_info.h         | 19 -------
>  arch/powerpc/kernel/asm-offsets.c              | 10 ++--
>  arch/powerpc/kernel/entry_32.S                 | 66 ++++++++--------------
>  arch/powerpc/kernel/entry_64.S                 | 12 ++--
>  arch/powerpc/kernel/epapr_hcalls.S             |  5 +-
>  arch/powerpc/kernel/exceptions-64e.S           | 13 +----
>  arch/powerpc/kernel/exceptions-64s.S           |  2 +-
>  arch/powerpc/kernel/head_32.S                  | 14 ++---
>  arch/powerpc/kernel/head_40x.S                 |  4 +-
>  arch/powerpc/kernel/head_44x.S                 |  8 +--
>  arch/powerpc/kernel/head_64.S                  |  1 +
>  arch/powerpc/kernel/head_8xx.S                 |  2 +-
>  arch/powerpc/kernel/head_booke.h               | 12 +---
>  arch/powerpc/kernel/head_fsl_booke.S           | 16 +++---
>  arch/powerpc/kernel/idle_6xx.S                 |  8 +--
>  arch/powerpc/kernel/idle_book3e.S              |  2 +-
>  arch/powerpc/kernel/idle_e500.S                |  8 +--
>  arch/powerpc/kernel/idle_power4.S              |  2 +-
>  arch/powerpc/kernel/irq.c                      | 77 +++++---------------------
>  arch/powerpc/kernel/kgdb.c                     | 28 ----------
>  arch/powerpc/kernel/machine_kexec_64.c         |  6 +-
>  arch/powerpc/kernel/misc_32.S                  | 17 +++---
>  arch/powerpc/kernel/process.c                  | 17 +++---
>  arch/powerpc/kernel/setup-common.c             |  2 +-
>  arch/powerpc/kernel/setup_32.c                 | 15 ++---
>  arch/powerpc/kernel/setup_64.c                 | 41 ++++----------
>  arch/powerpc/kernel/smp.c                      | 16 +++---
>  arch/powerpc/kernel/trace/ftrace_64_mprofile.S |  6 +-
>  arch/powerpc/kvm/book3s_hv_hmi.c               |  1 +
>  arch/powerpc/mm/hash_low_32.S                  | 14 ++---
>  arch/powerpc/net/bpf_jit32.h                   |  5 +-
>  arch/powerpc/sysdev/6xx-suspend.S              |  5 +-
>  arch/powerpc/xmon/xmon.c                       |  2 +-
>  45 files changed, 230 insertions(+), 368 deletions(-)
>  create mode 100644 arch/powerpc/include/asm/task_size_user64.h
> 

Re: [PATCH v6 0/9] powerpc: Switch to CONFIG_THREAD_INFO_IN_TASK

[Nicholas Piggin]

On Mon, 08 Oct 2018 20:59:56 +1100
Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:

> On Mon, 2018-10-08 at 09:16 +0000, Christophe Leroy wrote:
> > The purpose of this serie is to activate CONFIG_THREAD_INFO_IN_TASK which
> > moves the thread_info into task_struct.  
> 
> We need to make sure we don't have code that assumes that we don't take
> faults on TI access.
> 
> On ppc64, the stack SLB entries are bolted, which means the TI is too.
> 
> We might have code that assumes that we don't get SLB faults when
> accessing TI. If not, we're fine but that needs a close look.

Oh, we do. I think the entry side might be okay, but on exit we have
at least one (in syscall and interrupt exit both):

        /*
         * Disable interrupts so current_thread_info()->flags can't change,
         * and so that we don't get interrupted after loading SRR0/1.
         */
#ifdef CONFIG_PPC_BOOK3E
        wrteei  0
#else
        /*
         * For performance reasons we clear RI the same time that we
         * clear EE. We only need to clear RI just before we restore r13
         * below, but batching it with EE saves us one expensive mtmsrd call.
         * We have to be careful to restore RI if we branch anywhere from
         * here (eg syscall_exit_work).
         */
        li      r11,0
        mtmsrd  r11,1
#endif /* CONFIG_PPC_BOOK3E */

        ld      r9,TI_FLAGS(r12)

So taking an SLB there will cause an unrecoverable.

I think we can probably get rid of that optimization for now. I've found
for non-trivial syscalls it's often a loss if FP was used. I have a
couple of different options I'm working on to get rid of the mtmsrd
entirely we can go with instead (but I don't think those have to come
before Christophe's patch).

Thanks,
Nick