* [PATCHv2 01/11] arm64: thread_info remove stale items
2016-11-03 20:23 [PATCHv2 00/11] arm64: move thread_info off of the task stack Mark Rutland
@ 2016-11-03 20:23 ` Mark Rutland
2016-11-03 20:23 ` [PATCHv2 02/11] arm64: asm-offsets: remove unused definitions Mark Rutland
` (10 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: Mark Rutland @ 2016-11-03 20:23 UTC (permalink / raw)
To: linux-arm-kernel
We have a comment claiming __switch_to() cares about where cpu_context
is located relative to cpu_domain in thread_info. However arm64 has
never had a thread_info::cpu_domain field, and neither __switch_to nor
cpu_switch_to care where the cpu_context field is relative to others.
Additionally, the init_thread_info alias is never used anywhere in the
kernel, and will shortly become problematic when thread_info is moved
into task_struct.
This patch removes both.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/thread_info.h | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index e9ea5a6..76a9559 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -42,7 +42,6 @@ typedef unsigned long mm_segment_t;
/*
* low level task data that entry.S needs immediate access to.
- * __switch_to() assumes cpu_context follows immediately after cpu_domain.
*/
struct thread_info {
unsigned long flags; /* low level flags */
@@ -60,7 +59,6 @@ struct thread_info {
.addr_limit = KERNEL_DS, \
}
-#define init_thread_info (init_thread_union.thread_info)
#define init_stack (init_thread_union.stack)
/*
--
2.7.4
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCHv2 02/11] arm64: asm-offsets: remove unused definitions
2016-11-03 20:23 [PATCHv2 00/11] arm64: move thread_info off of the task stack Mark Rutland
2016-11-03 20:23 ` [PATCHv2 01/11] arm64: thread_info remove stale items Mark Rutland
@ 2016-11-03 20:23 ` Mark Rutland
2016-11-03 20:23 ` [PATCHv2 03/11] arm64: factor out current_stack_pointer Mark Rutland
` (9 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: Mark Rutland @ 2016-11-03 20:23 UTC (permalink / raw)
To: linux-arm-kernel
Subsequent patches will move the thread_info::{task,cpu} fields, and the
current TI_{TASK,CPU} offset definitions are not used anywhere.
This patch removes the redundant definitions.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/kernel/asm-offsets.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 4a2f0f0..d30b232 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -39,8 +39,6 @@ int main(void)
DEFINE(TI_FLAGS, offsetof(struct thread_info, flags));
DEFINE(TI_PREEMPT, offsetof(struct thread_info, preempt_count));
DEFINE(TI_ADDR_LIMIT, offsetof(struct thread_info, addr_limit));
- DEFINE(TI_TASK, offsetof(struct thread_info, task));
- DEFINE(TI_CPU, offsetof(struct thread_info, cpu));
BLANK();
DEFINE(THREAD_CPU_CONTEXT, offsetof(struct task_struct, thread.cpu_context));
BLANK();
--
2.7.4
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCHv2 03/11] arm64: factor out current_stack_pointer
2016-11-03 20:23 [PATCHv2 00/11] arm64: move thread_info off of the task stack Mark Rutland
2016-11-03 20:23 ` [PATCHv2 01/11] arm64: thread_info remove stale items Mark Rutland
2016-11-03 20:23 ` [PATCHv2 02/11] arm64: asm-offsets: remove unused definitions Mark Rutland
@ 2016-11-03 20:23 ` Mark Rutland
2016-11-03 20:23 ` [PATCHv2 04/11] arm64: traps: simplify die() and __die() Mark Rutland
` (8 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: Mark Rutland @ 2016-11-03 20:23 UTC (permalink / raw)
To: linux-arm-kernel
We define current_stack_pointer in <asm/thread_info.h>, though other
files and header relying upon it do not have this necessary include, and
are thus fragile to changes in the header soup.
Subsequent patches will affect the header soup such that directly
including <asm/thread_info.h> may result in a circular header include in
some of these cases, so we can't simply include <asm/thread_info.h>.
Instead, factor current_thread_info into its own header, and have all
existing users include this explicitly.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/percpu.h | 2 ++
arch/arm64/include/asm/perf_event.h | 2 ++
arch/arm64/include/asm/stack_pointer.h | 9 +++++++++
arch/arm64/include/asm/thread_info.h | 6 +-----
arch/arm64/kernel/return_address.c | 1 +
arch/arm64/kernel/stacktrace.c | 1 +
arch/arm64/kernel/traps.c | 1 +
7 files changed, 17 insertions(+), 5 deletions(-)
create mode 100644 arch/arm64/include/asm/stack_pointer.h
diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h
index 5394c84..d7a3c62 100644
--- a/arch/arm64/include/asm/percpu.h
+++ b/arch/arm64/include/asm/percpu.h
@@ -16,6 +16,8 @@
#ifndef __ASM_PERCPU_H
#define __ASM_PERCPU_H
+#include <asm/stack_pointer.h>
+
static inline void set_my_cpu_offset(unsigned long off)
{
asm volatile("msr tpidr_el1, %0" :: "r" (off) : "memory");
diff --git a/arch/arm64/include/asm/perf_event.h b/arch/arm64/include/asm/perf_event.h
index 2065f46..9eee2be 100644
--- a/arch/arm64/include/asm/perf_event.h
+++ b/arch/arm64/include/asm/perf_event.h
@@ -17,6 +17,8 @@
#ifndef __ASM_PERF_EVENT_H
#define __ASM_PERF_EVENT_H
+#include <asm/stack_pointer.h>
+
#define ARMV8_PMU_MAX_COUNTERS 32
#define ARMV8_PMU_COUNTER_MASK (ARMV8_PMU_MAX_COUNTERS - 1)
diff --git a/arch/arm64/include/asm/stack_pointer.h b/arch/arm64/include/asm/stack_pointer.h
new file mode 100644
index 0000000..ffcdf74
--- /dev/null
+++ b/arch/arm64/include/asm/stack_pointer.h
@@ -0,0 +1,9 @@
+#ifndef __ASM_STACK_POINTER_H
+#define __ASM_STACK_POINTER_H
+
+/*
+ * how to get the current stack pointer from C
+ */
+register unsigned long current_stack_pointer asm ("sp");
+
+#endif /* __ASM_STACK_POINTER_H */
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 76a9559..3a4f85d 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -36,6 +36,7 @@
struct task_struct;
+#include <asm/stack_pointer.h>
#include <asm/types.h>
typedef unsigned long mm_segment_t;
@@ -62,11 +63,6 @@ struct thread_info {
#define init_stack (init_thread_union.stack)
/*
- * how to get the current stack pointer from C
- */
-register unsigned long current_stack_pointer asm ("sp");
-
-/*
* how to get the thread information struct from C
*/
static inline struct thread_info *current_thread_info(void) __attribute_const__;
diff --git a/arch/arm64/kernel/return_address.c b/arch/arm64/kernel/return_address.c
index 1718706..12a87f2 100644
--- a/arch/arm64/kernel/return_address.c
+++ b/arch/arm64/kernel/return_address.c
@@ -12,6 +12,7 @@
#include <linux/export.h>
#include <linux/ftrace.h>
+#include <asm/stack_pointer.h>
#include <asm/stacktrace.h>
struct return_address_data {
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index c2efddf..5b80068 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -22,6 +22,7 @@
#include <linux/stacktrace.h>
#include <asm/irq.h>
+#include <asm/stack_pointer.h>
#include <asm/stacktrace.h>
/*
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index c9986b3..95a5452 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -38,6 +38,7 @@
#include <asm/esr.h>
#include <asm/insn.h>
#include <asm/traps.h>
+#include <asm/stack_pointer.h>
#include <asm/stacktrace.h>
#include <asm/exception.h>
#include <asm/system_misc.h>
--
2.7.4
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCHv2 04/11] arm64: traps: simplify die() and __die()
2016-11-03 20:23 [PATCHv2 00/11] arm64: move thread_info off of the task stack Mark Rutland
` (2 preceding siblings ...)
2016-11-03 20:23 ` [PATCHv2 03/11] arm64: factor out current_stack_pointer Mark Rutland
@ 2016-11-03 20:23 ` Mark Rutland
2016-11-03 20:23 ` [PATCHv2 05/11] arm64: unexport walk_stackframe Mark Rutland
` (7 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: Mark Rutland @ 2016-11-03 20:23 UTC (permalink / raw)
To: linux-arm-kernel
In arm64's die and __die routines we pass around a thread_info, and
subsequently use this to determine the relevant task_struct, and the end
of the thread's stack. Subsequent patches will decouple thread_info from
the stack, and this approach will no longer work.
To figure out the end of the stack, we can use the new generic
end_of_stack() helper. As we only call __die() from die(), and die()
always deals with the current task, we can remove the parameter and have
both acquire current directly, which also makes it clear that __die
can't be called for arbitrary tasks.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/kernel/traps.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 95a5452..7ac30bf 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -228,10 +228,9 @@ void show_stack(struct task_struct *tsk, unsigned long *sp)
#endif
#define S_SMP " SMP"
-static int __die(const char *str, int err, struct thread_info *thread,
- struct pt_regs *regs)
+static int __die(const char *str, int err, struct pt_regs *regs)
{
- struct task_struct *tsk = thread->task;
+ struct task_struct *tsk = current;
static int die_counter;
int ret;
@@ -246,7 +245,8 @@ static int __die(const char *str, int err, struct thread_info *thread,
print_modules();
__show_regs(regs);
pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
- TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
+ TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk),
+ end_of_stack(tsk));
if (!user_mode(regs)) {
dump_mem(KERN_EMERG, "Stack: ", regs->sp,
@@ -265,7 +265,6 @@ static DEFINE_RAW_SPINLOCK(die_lock);
*/
void die(const char *str, struct pt_regs *regs, int err)
{
- struct thread_info *thread = current_thread_info();
int ret;
oops_enter();
@@ -273,9 +272,9 @@ void die(const char *str, struct pt_regs *regs, int err)
raw_spin_lock_irq(&die_lock);
console_verbose();
bust_spinlocks(1);
- ret = __die(str, err, thread, regs);
+ ret = __die(str, err, regs);
- if (regs && kexec_should_crash(thread->task))
+ if (regs && kexec_should_crash(current))
crash_kexec(regs);
bust_spinlocks(0);
--
2.7.4
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCHv2 05/11] arm64: unexport walk_stackframe
2016-11-03 20:23 [PATCHv2 00/11] arm64: move thread_info off of the task stack Mark Rutland
` (3 preceding siblings ...)
2016-11-03 20:23 ` [PATCHv2 04/11] arm64: traps: simplify die() and __die() Mark Rutland
@ 2016-11-03 20:23 ` Mark Rutland
2016-11-03 20:23 ` [PATCHv2 06/11] arm64: prep stack walkers for THREAD_INFO_IN_TASK Mark Rutland
` (6 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: Mark Rutland @ 2016-11-03 20:23 UTC (permalink / raw)
To: linux-arm-kernel
The walk_stackframe functions is architecture-specific, with a varying
prototype, and common code should not use it directly. None of its
current users can be built as modules. With THREAD_INFO_IN_TASK, users
will also need to hold a stack reference before calling it.
There's no reason for it to be exported, and it's very easy to misuse,
so unexport it for now.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm64/kernel/stacktrace.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 5b80068..d53f99d 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -129,7 +129,6 @@ void notrace walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
break;
}
}
-EXPORT_SYMBOL(walk_stackframe);
#ifdef CONFIG_STACKTRACE
struct stack_trace_data {
--
2.7.4
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCHv2 06/11] arm64: prep stack walkers for THREAD_INFO_IN_TASK
2016-11-03 20:23 [PATCHv2 00/11] arm64: move thread_info off of the task stack Mark Rutland
` (4 preceding siblings ...)
2016-11-03 20:23 ` [PATCHv2 05/11] arm64: unexport walk_stackframe Mark Rutland
@ 2016-11-03 20:23 ` Mark Rutland
2016-11-03 20:23 ` [PATCHv2 07/11] arm64: move sp_el0 and tpidr_el1 into cpu_suspend_ctx Mark Rutland
` (5 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: Mark Rutland @ 2016-11-03 20:23 UTC (permalink / raw)
To: linux-arm-kernel
When CONFIG_THREAD_INFO_IN_TASK is selected, task stacks may be freed
before a task is destroyed. To account for this, the stacks are
refcounted, and when manipulating the stack of another task, it is
necessary to get/put the stack to ensure it isn't freed and/or re-used
while we do so.
This patch reworks the arm64 stack walking code to account for this.
When CONFIG_THREAD_INFO_IN_TASK is not selected these perform no
refcounting, and this should only be a structural change that does not
affect behaviour.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/kernel/process.c | 20 ++++++++++++++------
arch/arm64/kernel/stacktrace.c | 5 +++++
arch/arm64/kernel/traps.c | 5 +++++
3 files changed, 24 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 01753cd..ec7b9c0 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -350,27 +350,35 @@ struct task_struct *__switch_to(struct task_struct *prev,
unsigned long get_wchan(struct task_struct *p)
{
struct stackframe frame;
- unsigned long stack_page;
+ unsigned long stack_page, ret = 0;
int count = 0;
if (!p || p == current || p->state == TASK_RUNNING)
return 0;
+ stack_page = (unsigned long)try_get_task_stack(p);
+ if (!stack_page)
+ return 0;
+
frame.fp = thread_saved_fp(p);
frame.sp = thread_saved_sp(p);
frame.pc = thread_saved_pc(p);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
frame.graph = p->curr_ret_stack;
#endif
- stack_page = (unsigned long)task_stack_page(p);
do {
if (frame.sp < stack_page ||
frame.sp >= stack_page + THREAD_SIZE ||
unwind_frame(p, &frame))
- return 0;
- if (!in_sched_functions(frame.pc))
- return frame.pc;
+ goto out;
+ if (!in_sched_functions(frame.pc)) {
+ ret = frame.pc;
+ goto out;
+ }
} while (count ++ < 16);
- return 0;
+
+out:
+ put_task_stack(p);
+ return ret;
}
unsigned long arch_align_stack(unsigned long sp)
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index d53f99d..8a552a3 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -181,6 +181,9 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
struct stack_trace_data data;
struct stackframe frame;
+ if (!try_get_task_stack(tsk))
+ return;
+
data.trace = trace;
data.skip = trace->skip;
@@ -202,6 +205,8 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
walk_stackframe(tsk, &frame, save_trace, &data);
if (trace->nr_entries < trace->max_entries)
trace->entries[trace->nr_entries++] = ULONG_MAX;
+
+ put_task_stack(tsk);
}
void save_stack_trace(struct stack_trace *trace)
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 7ac30bf..4731133 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -148,6 +148,9 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
if (!tsk)
tsk = current;
+ if (!try_get_task_stack(tsk))
+ return;
+
/*
* Switching between stacks is valid when tracing current and in
* non-preemptible context.
@@ -213,6 +216,8 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
stack + sizeof(struct pt_regs));
}
}
+
+ put_task_stack(tsk);
}
void show_stack(struct task_struct *tsk, unsigned long *sp)
--
2.7.4
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCHv2 07/11] arm64: move sp_el0 and tpidr_el1 into cpu_suspend_ctx
2016-11-03 20:23 [PATCHv2 00/11] arm64: move thread_info off of the task stack Mark Rutland
` (5 preceding siblings ...)
2016-11-03 20:23 ` [PATCHv2 06/11] arm64: prep stack walkers for THREAD_INFO_IN_TASK Mark Rutland
@ 2016-11-03 20:23 ` Mark Rutland
2016-11-03 20:23 ` [PATCHv2 08/11] arm64: smp: prepare for smp_processor_id() rework Mark Rutland
` (4 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: Mark Rutland @ 2016-11-03 20:23 UTC (permalink / raw)
To: linux-arm-kernel
When returning from idle, we rely on the fact that thread_info lives at
the end of the kernel stack, and restore this by masking the saved stack
pointer. Subsequent patches will sever the relationship between the
stack and thread_info, and to cater for this we must save/restore sp_el0
explicitly, storing it in cpu_suspend_ctx.
As cpu_suspend_ctx must be doubleword aligned, this leaves us with an
extra slot in cpu_suspend_ctx. We can use this to save/restore tpidr_el1
in the same way, which simplifies the code, avoiding pointer chasing on
the restore path (as we no longer need to load thread_info::cpu followed
by the relevant slot in __per_cpu_offset based on this).
This patch stashes both registers in cpu_suspend_ctx.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/suspend.h | 2 +-
arch/arm64/kernel/sleep.S | 3 ---
arch/arm64/kernel/suspend.c | 6 ------
arch/arm64/mm/proc.S | 6 ++++++
4 files changed, 7 insertions(+), 10 deletions(-)
diff --git a/arch/arm64/include/asm/suspend.h b/arch/arm64/include/asm/suspend.h
index b8a313f..de5600f 100644
--- a/arch/arm64/include/asm/suspend.h
+++ b/arch/arm64/include/asm/suspend.h
@@ -1,7 +1,7 @@
#ifndef __ASM_SUSPEND_H
#define __ASM_SUSPEND_H
-#define NR_CTX_REGS 10
+#define NR_CTX_REGS 12
#define NR_CALLEE_SAVED_REGS 12
/*
diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index 1bec41b..df67652 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S
@@ -125,9 +125,6 @@ ENTRY(_cpu_resume)
/* load sp from context */
ldr x2, [x0, #CPU_CTX_SP]
mov sp, x2
- /* save thread_info */
- and x2, x2, #~(THREAD_SIZE - 1)
- msr sp_el0, x2
/*
* cpu_do_resume expects x0 to contain context address pointer
*/
diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
index bb0cd78..1e3be90 100644
--- a/arch/arm64/kernel/suspend.c
+++ b/arch/arm64/kernel/suspend.c
@@ -47,12 +47,6 @@ void notrace __cpu_suspend_exit(void)
cpu_uninstall_idmap();
/*
- * Restore per-cpu offset before any kernel
- * subsystem relying on it has a chance to run.
- */
- set_my_cpu_offset(per_cpu_offset(cpu));
-
- /*
* PSTATE was not saved over suspend/resume, re-enable any detected
* features that might not have been set correctly.
*/
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 352c73b..6a853a8 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -70,11 +70,14 @@ ENTRY(cpu_do_suspend)
mrs x8, mdscr_el1
mrs x9, oslsr_el1
mrs x10, sctlr_el1
+ mrs x11, tpidr_el1
+ mrs x12, sp_el0
stp x2, x3, [x0]
stp x4, xzr, [x0, #16]
stp x5, x6, [x0, #32]
stp x7, x8, [x0, #48]
stp x9, x10, [x0, #64]
+ stp x11, x12, [x0, #80]
ret
ENDPROC(cpu_do_suspend)
@@ -90,6 +93,7 @@ ENTRY(cpu_do_resume)
ldp x6, x8, [x0, #32]
ldp x9, x10, [x0, #48]
ldp x11, x12, [x0, #64]
+ ldp x13, x14, [x0, #80]
msr tpidr_el0, x2
msr tpidrro_el0, x3
msr contextidr_el1, x4
@@ -112,6 +116,8 @@ ENTRY(cpu_do_resume)
msr mdscr_el1, x10
msr sctlr_el1, x12
+ msr tpidr_el1, x13
+ msr sp_el0, x14
/*
* Restore oslsr_el1 by writing oslar_el1
*/
--
2.7.4
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCHv2 08/11] arm64: smp: prepare for smp_processor_id() rework
2016-11-03 20:23 [PATCHv2 00/11] arm64: move thread_info off of the task stack Mark Rutland
` (6 preceding siblings ...)
2016-11-03 20:23 ` [PATCHv2 07/11] arm64: move sp_el0 and tpidr_el1 into cpu_suspend_ctx Mark Rutland
@ 2016-11-03 20:23 ` Mark Rutland
2016-11-03 20:23 ` [PATCHv2 09/11] arm64: make cpu number a percpu variable Mark Rutland
` (3 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: Mark Rutland @ 2016-11-03 20:23 UTC (permalink / raw)
To: linux-arm-kernel
Subsequent patches will make smp_processor_id() use a percpu variable.
This will make smp_processor_id() dependent on the percpu offset, and
thus we cannot use smp_processor_id() to figure out what to initialise
the offset to.
Prepare for this by initialising the percpu offset based on
current::cpu, which will work regardless of how smp_processor_id() is
implemented. Also, make this relationship obvious by placing this code
together at the start of secondary_start_kernel().
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/kernel/smp.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 8507703..f64401f 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -208,7 +208,10 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
asmlinkage void secondary_start_kernel(void)
{
struct mm_struct *mm = &init_mm;
- unsigned int cpu = smp_processor_id();
+ unsigned int cpu;
+
+ cpu = task_cpu(current);
+ set_my_cpu_offset(per_cpu_offset(cpu));
/*
* All kernel threads share the same mm context; grab a
@@ -217,8 +220,6 @@ asmlinkage void secondary_start_kernel(void)
atomic_inc(&mm->mm_count);
current->active_mm = mm;
- set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
-
/*
* TTBR0 is only used for the identity mapping at this stage. Make it
* point to zero page to avoid speculatively fetching new entries.
--
2.7.4
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCHv2 09/11] arm64: make cpu number a percpu variable
2016-11-03 20:23 [PATCHv2 00/11] arm64: move thread_info off of the task stack Mark Rutland
` (7 preceding siblings ...)
2016-11-03 20:23 ` [PATCHv2 08/11] arm64: smp: prepare for smp_processor_id() rework Mark Rutland
@ 2016-11-03 20:23 ` Mark Rutland
2016-11-03 20:23 ` [PATCHv2 10/11] arm64: assembler: introduce ldr_this_cpu Mark Rutland
` (2 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: Mark Rutland @ 2016-11-03 20:23 UTC (permalink / raw)
To: linux-arm-kernel
In the absence of CONFIG_THREAD_INFO_IN_TASK, core code maintains
thread_info::cpu, and low-level architecture code can access this to
build raw_smp_processor_id(). With CONFIG_THREAD_INFO_IN_TASK, core code
maintains task_struct::cpu, which for reasons of hte header soup is not
accessible to low-level arch code.
Instead, we can maintain a percpu variable containing the cpu number.
For both the old and new implementation of raw_smp_processor_id(), we
read a syreg into a GPR, add an offset, and load the result. As the
offset is now larger, it may not be folded into the load, but otherwise
the assembly shouldn't change much.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/smp.h | 11 ++++++++++-
arch/arm64/kernel/smp.c | 5 +++++
2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index 0226447..968b08d 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -29,11 +29,20 @@
#ifndef __ASSEMBLY__
+#include <asm/percpu.h>
+
#include <linux/threads.h>
#include <linux/cpumask.h>
#include <linux/thread_info.h>
-#define raw_smp_processor_id() (current_thread_info()->cpu)
+DECLARE_PER_CPU_READ_MOSTLY(int, cpu_number);
+
+/*
+ * We don't use this_cpu_read(cpu_number) as that has implicit writes to
+ * preempt_count, and associated (compiler) barriers, that we'd like to avoid
+ * the expense of. If we're preemptible, the value can be stale at use anyway.
+ */
+#define raw_smp_processor_id() (*this_cpu_ptr(&cpu_number))
struct seq_file;
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index f64401f..6f42c68 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -58,6 +58,9 @@
#define CREATE_TRACE_POINTS
#include <trace/events/ipi.h>
+DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
+EXPORT_PER_CPU_SYMBOL(cpu_number);
+
/*
* as from 2.5, kernels no longer have an init_tasks structure
* so we need some other way of telling a new secondary core
@@ -719,6 +722,8 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
*/
for_each_possible_cpu(cpu) {
+ per_cpu(cpu_number, cpu) = cpu;
+
if (cpu == smp_processor_id())
continue;
--
2.7.4
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCHv2 10/11] arm64: assembler: introduce ldr_this_cpu
2016-11-03 20:23 [PATCHv2 00/11] arm64: move thread_info off of the task stack Mark Rutland
` (8 preceding siblings ...)
2016-11-03 20:23 ` [PATCHv2 09/11] arm64: make cpu number a percpu variable Mark Rutland
@ 2016-11-03 20:23 ` Mark Rutland
2016-11-03 20:23 ` [PATCHv2 11/11] arm64: split thread_info from task stack Mark Rutland
2016-11-14 17:50 ` [PATCHv2 00/11] arm64: move thread_info off of the " Catalin Marinas
11 siblings, 0 replies; 13+ messages in thread
From: Mark Rutland @ 2016-11-03 20:23 UTC (permalink / raw)
To: linux-arm-kernel
Shortly we will want to load a percpu variable in the return from
userspace path. We can save an instruction by folding the addition of
the percpu offset into the load instruction, and this patch adds a new
helper to do so.
At the same time, we clean up this_cpu_ptr for consistency. As with
{adr,ldr,str}_l, we change the template to take the destination register
first, and name this dst. Secondly, we rename the macro to adr_this_cpu,
following the scheme of adr_l, and matching the newly added
ldr_this_cpu.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/assembler.h | 19 +++++++++++++++----
arch/arm64/kernel/entry.S | 2 +-
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 28bfe61..128a9ca 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -202,14 +202,25 @@ lr .req x30 // link register
.endm
/*
+ * @dst: Result of per_cpu(sym, smp_processor_id())
* @sym: The name of the per-cpu variable
- * @reg: Result of per_cpu(sym, smp_processor_id())
* @tmp: scratch register
*/
- .macro this_cpu_ptr, sym, reg, tmp
- adr_l \reg, \sym
+ .macro adr_this_cpu, dst, sym, tmp
+ adr_l \dst, \sym
mrs \tmp, tpidr_el1
- add \reg, \reg, \tmp
+ add \dst, \dst, \tmp
+ .endm
+
+ /*
+ * @dst: Result of READ_ONCE(per_cpu(sym, smp_processor_id()))
+ * @sym: The name of the per-cpu variable
+ * @tmp: scratch register
+ */
+ .macro ldr_this_cpu dst, sym, tmp
+ adr_l \dst, \sym
+ mrs \tmp, tpidr_el1
+ ldr \dst, [\dst, \tmp]
.endm
/*
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 223d54a..2d4c83b 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -200,7 +200,7 @@ alternative_else_nop_endif
cmp x25, tsk
b.ne 9998f
- this_cpu_ptr irq_stack, x25, x26
+ adr_this_cpu x25, irq_stack, x26
mov x26, #IRQ_STACK_START_SP
add x26, x25, x26
--
2.7.4
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCHv2 11/11] arm64: split thread_info from task stack
2016-11-03 20:23 [PATCHv2 00/11] arm64: move thread_info off of the task stack Mark Rutland
` (9 preceding siblings ...)
2016-11-03 20:23 ` [PATCHv2 10/11] arm64: assembler: introduce ldr_this_cpu Mark Rutland
@ 2016-11-03 20:23 ` Mark Rutland
2016-11-14 17:50 ` [PATCHv2 00/11] arm64: move thread_info off of the " Catalin Marinas
11 siblings, 0 replies; 13+ messages in thread
From: Mark Rutland @ 2016-11-03 20:23 UTC (permalink / raw)
To: linux-arm-kernel
This patch moves arm64's struct thread_info from the task stack into
task_struct. This protects thread_info from corruption in the case of
stack overflows, and makes its address harder to determine if stack
addresses are leaked, making a number of attacks more difficult. Precise
detection and handling of overflow is left for subsequent patches.
Largely, this involves changing code to store the task_struct in sp_el0,
and acquire the thread_info from the task struct. Core code now
implements current_thread_info(), and as noted in <linux/sched.h> this
relies on offsetof(task_struct, thread_info) == 0, enforced by core
code.
This change means that the 'tsk' register used in entry.S now points to
a task_struct, rather than a thread_info as it used to. To make this
clear, the TI_* field offsets are renamed to TSK_TI_*, with asm-offsets
appropriately updated to account for the structural change.
Userspace clobbers sp_el0, and we can no longer restore this from the
stack. Instead, the current task is cached in a per-cpu variable that we
can safely access from early assembly as interrupts are disabled (and we
are thus not preemptible).
Both secondary entry and idle are updated to stash the sp and task
pointer separately.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/Kbuild | 1 -
arch/arm64/include/asm/current.h | 22 +++++++++++++++++++
arch/arm64/include/asm/smp.h | 1 +
arch/arm64/include/asm/thread_info.h | 24 ---------------------
arch/arm64/kernel/asm-offsets.c | 8 ++++---
arch/arm64/kernel/entry.S | 41 ++++++++++++++++++------------------
arch/arm64/kernel/head.S | 11 +++++-----
arch/arm64/kernel/process.c | 16 ++++++++++++++
arch/arm64/kernel/smp.c | 2 ++
10 files changed, 73 insertions(+), 54 deletions(-)
create mode 100644 arch/arm64/include/asm/current.h
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 969ef88..2a6fcec 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -109,6 +109,7 @@ config ARM64
select POWER_SUPPLY
select SPARSE_IRQ
select SYSCTL_EXCEPTION_TRACE
+ select THREAD_INFO_IN_TASK
help
ARM 64-bit (AArch64) Linux support.
diff --git a/arch/arm64/include/asm/Kbuild b/arch/arm64/include/asm/Kbuild
index 44e1d7f..28196b1 100644
--- a/arch/arm64/include/asm/Kbuild
+++ b/arch/arm64/include/asm/Kbuild
@@ -1,7 +1,6 @@
generic-y += bugs.h
generic-y += clkdev.h
generic-y += cputime.h
-generic-y += current.h
generic-y += delay.h
generic-y += div64.h
generic-y += dma.h
diff --git a/arch/arm64/include/asm/current.h b/arch/arm64/include/asm/current.h
new file mode 100644
index 0000000..f2bcbe2
--- /dev/null
+++ b/arch/arm64/include/asm/current.h
@@ -0,0 +1,22 @@
+#ifndef __ASM_CURRENT_H
+#define __ASM_CURRENT_H
+
+#include <linux/compiler.h>
+
+#include <asm/sysreg.h>
+
+#ifndef __ASSEMBLY__
+
+struct task_struct;
+
+static __always_inline struct task_struct *get_current(void)
+{
+ return (struct task_struct *)read_sysreg(sp_el0);
+}
+
+#define current get_current()
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ASM_CURRENT_H */
+
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index 968b08d..a62db95 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -82,6 +82,7 @@ asmlinkage void secondary_start_kernel(void);
*/
struct secondary_data {
void *stack;
+ struct task_struct *task;
long status;
};
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 3a4f85d..7a4e0e4 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -47,41 +47,17 @@ typedef unsigned long mm_segment_t;
struct thread_info {
unsigned long flags; /* low level flags */
mm_segment_t addr_limit; /* address limit */
- struct task_struct *task; /* main task structure */
int preempt_count; /* 0 => preemptable, <0 => bug */
- int cpu; /* cpu */
};
#define INIT_THREAD_INFO(tsk) \
{ \
- .task = &tsk, \
- .flags = 0, \
.preempt_count = INIT_PREEMPT_COUNT, \
.addr_limit = KERNEL_DS, \
}
#define init_stack (init_thread_union.stack)
-/*
- * how to get the thread information struct from C
- */
-static inline struct thread_info *current_thread_info(void) __attribute_const__;
-
-/*
- * struct thread_info can be accessed directly via sp_el0.
- *
- * We don't use read_sysreg() as we want the compiler to cache the value where
- * possible.
- */
-static inline struct thread_info *current_thread_info(void)
-{
- unsigned long sp_el0;
-
- asm ("mrs %0, sp_el0" : "=r" (sp_el0));
-
- return (struct thread_info *)sp_el0;
-}
-
#define thread_saved_pc(tsk) \
((unsigned long)(tsk->thread.cpu_context.pc))
#define thread_saved_sp(tsk) \
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index d30b232..c2dc9fa 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -36,9 +36,10 @@ int main(void)
{
DEFINE(TSK_ACTIVE_MM, offsetof(struct task_struct, active_mm));
BLANK();
- DEFINE(TI_FLAGS, offsetof(struct thread_info, flags));
- DEFINE(TI_PREEMPT, offsetof(struct thread_info, preempt_count));
- DEFINE(TI_ADDR_LIMIT, offsetof(struct thread_info, addr_limit));
+ DEFINE(TSK_TI_FLAGS, offsetof(struct task_struct, thread_info.flags));
+ DEFINE(TSK_TI_PREEMPT, offsetof(struct task_struct, thread_info.preempt_count));
+ DEFINE(TSK_TI_ADDR_LIMIT, offsetof(struct task_struct, thread_info.addr_limit));
+ DEFINE(TSK_STACK, offsetof(struct task_struct, stack));
BLANK();
DEFINE(THREAD_CPU_CONTEXT, offsetof(struct task_struct, thread.cpu_context));
BLANK();
@@ -121,6 +122,7 @@ int main(void)
DEFINE(TZ_DSTTIME, offsetof(struct timezone, tz_dsttime));
BLANK();
DEFINE(CPU_BOOT_STACK, offsetof(struct secondary_data, stack));
+ DEFINE(CPU_BOOT_TASK, offsetof(struct secondary_data, task));
BLANK();
#ifdef CONFIG_KVM_ARM_HOST
DEFINE(VCPU_CONTEXT, offsetof(struct kvm_vcpu, arch.ctxt));
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 2d4c83b..6349a83 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -90,9 +90,8 @@
.if \el == 0
mrs x21, sp_el0
- mov tsk, sp
- and tsk, tsk, #~(THREAD_SIZE - 1) // Ensure MDSCR_EL1.SS is clear,
- ldr x19, [tsk, #TI_FLAGS] // since we can unmask debug
+ ldr_this_cpu tsk, __entry_task, x20 // Ensure MDSCR_EL1.SS is clear,
+ ldr x19, [tsk, #TSK_TI_FLAGS] // since we can unmask debug
disable_step_tsk x19, x20 // exceptions when scheduling.
mov x29, xzr // fp pointed to user-space
@@ -100,10 +99,10 @@
add x21, sp, #S_FRAME_SIZE
get_thread_info tsk
/* Save the task's original addr_limit and set USER_DS (TASK_SIZE_64) */
- ldr x20, [tsk, #TI_ADDR_LIMIT]
+ ldr x20, [tsk, #TSK_TI_ADDR_LIMIT]
str x20, [sp, #S_ORIG_ADDR_LIMIT]
mov x20, #TASK_SIZE_64
- str x20, [tsk, #TI_ADDR_LIMIT]
+ str x20, [tsk, #TSK_TI_ADDR_LIMIT]
/* No need to reset PSTATE.UAO, hardware's already set it to 0 for us */
.endif /* \el == 0 */
mrs x22, elr_el1
@@ -139,7 +138,7 @@
.if \el != 0
/* Restore the task's original addr_limit. */
ldr x20, [sp, #S_ORIG_ADDR_LIMIT]
- str x20, [tsk, #TI_ADDR_LIMIT]
+ str x20, [tsk, #TSK_TI_ADDR_LIMIT]
/* No need to restore UAO, it will be restored from SPSR_EL1 */
.endif
@@ -192,13 +191,14 @@ alternative_else_nop_endif
mov x19, sp // preserve the original sp
/*
- * Compare sp with the current thread_info, if the top
- * ~(THREAD_SIZE - 1) bits match, we are on a task stack, and
- * should switch to the irq stack.
+ * Compare sp with the base of the task stack.
+ * If the top ~(THREAD_SIZE - 1) bits match, we are on a task stack,
+ * and should switch to the irq stack.
*/
- and x25, x19, #~(THREAD_SIZE - 1)
- cmp x25, tsk
- b.ne 9998f
+ ldr x25, [tsk, TSK_STACK]
+ eor x25, x25, x19
+ and x25, x25, #~(THREAD_SIZE - 1)
+ cbnz x25, 9998f
adr_this_cpu x25, irq_stack, x26
mov x26, #IRQ_STACK_START_SP
@@ -427,9 +427,9 @@ el1_irq:
irq_handler
#ifdef CONFIG_PREEMPT
- ldr w24, [tsk, #TI_PREEMPT] // get preempt count
+ ldr w24, [tsk, #TSK_TI_PREEMPT] // get preempt count
cbnz w24, 1f // preempt count != 0
- ldr x0, [tsk, #TI_FLAGS] // get flags
+ ldr x0, [tsk, #TSK_TI_FLAGS] // get flags
tbz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling?
bl el1_preempt
1:
@@ -444,7 +444,7 @@ ENDPROC(el1_irq)
el1_preempt:
mov x24, lr
1: bl preempt_schedule_irq // irq en/disable is done inside
- ldr x0, [tsk, #TI_FLAGS] // get new tasks TI_FLAGS
+ ldr x0, [tsk, #TSK_TI_FLAGS] // get new tasks TI_FLAGS
tbnz x0, #TIF_NEED_RESCHED, 1b // needs rescheduling?
ret x24
#endif
@@ -674,8 +674,7 @@ ENTRY(cpu_switch_to)
ldp x29, x9, [x8], #16
ldr lr, [x8]
mov sp, x9
- and x9, x9, #~(THREAD_SIZE - 1)
- msr sp_el0, x9
+ msr sp_el0, x1
ret
ENDPROC(cpu_switch_to)
@@ -686,7 +685,7 @@ ENDPROC(cpu_switch_to)
ret_fast_syscall:
disable_irq // disable interrupts
str x0, [sp, #S_X0] // returned x0
- ldr x1, [tsk, #TI_FLAGS] // re-check for syscall tracing
+ ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for syscall tracing
and x2, x1, #_TIF_SYSCALL_WORK
cbnz x2, ret_fast_syscall_trace
and x2, x1, #_TIF_WORK_MASK
@@ -706,14 +705,14 @@ work_pending:
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_on // enabled while in userspace
#endif
- ldr x1, [tsk, #TI_FLAGS] // re-check for single-step
+ ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for single-step
b finish_ret_to_user
/*
* "slow" syscall return path.
*/
ret_to_user:
disable_irq // disable interrupts
- ldr x1, [tsk, #TI_FLAGS]
+ ldr x1, [tsk, #TSK_TI_FLAGS]
and x2, x1, #_TIF_WORK_MASK
cbnz x2, work_pending
finish_ret_to_user:
@@ -746,7 +745,7 @@ el0_svc_naked: // compat entry point
enable_dbg_and_irq
ct_user_exit 1
- ldr x16, [tsk, #TI_FLAGS] // check for syscall hooks
+ ldr x16, [tsk, #TSK_TI_FLAGS] // check for syscall hooks
tst x16, #_TIF_SYSCALL_WORK
b.ne __sys_trace
cmp scno, sc_nr // check upper syscall limit
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 332e331..eaafb25 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -428,7 +428,8 @@ ENDPROC(__create_page_tables)
__primary_switched:
adrp x4, init_thread_union
add sp, x4, #THREAD_SIZE
- msr sp_el0, x4 // Save thread_info
+ adr_l x5, init_task
+ msr sp_el0, x5 // Save thread_info
adr_l x8, vectors // load VBAR_EL1 with virtual
msr vbar_el1, x8 // vector table address
@@ -699,10 +700,10 @@ __secondary_switched:
isb
adr_l x0, secondary_data
- ldr x0, [x0, #CPU_BOOT_STACK] // get secondary_data.stack
- mov sp, x0
- and x0, x0, #~(THREAD_SIZE - 1)
- msr sp_el0, x0 // save thread_info
+ ldr x1, [x0, #CPU_BOOT_STACK] // get secondary_data.stack
+ mov sp, x1
+ ldr x2, [x0, #CPU_BOOT_TASK]
+ msr sp_el0, x2
mov x29, #0
b secondary_start_kernel
ENDPROC(__secondary_switched)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index ec7b9c0..a98b743 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -45,6 +45,7 @@
#include <linux/personality.h>
#include <linux/notifier.h>
#include <trace/events/power.h>
+#include <linux/percpu.h>
#include <asm/alternative.h>
#include <asm/compat.h>
@@ -322,6 +323,20 @@ void uao_thread_switch(struct task_struct *next)
}
/*
+ * We store our current task in sp_el0, which is clobbered by userspace. Keep a
+ * shadow copy so that we can restore this upon entry from userspace.
+ *
+ * This is *only* for exception entry from EL0, and is not valid until we
+ * __switch_to() a user task.
+ */
+DEFINE_PER_CPU(struct task_struct *, __entry_task);
+
+static void entry_task_switch(struct task_struct *next)
+{
+ __this_cpu_write(__entry_task, next);
+}
+
+/*
* Thread switching.
*/
struct task_struct *__switch_to(struct task_struct *prev,
@@ -333,6 +348,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
tls_thread_switch(next);
hw_breakpoint_thread_switch(next);
contextidr_thread_switch(next);
+ entry_task_switch(next);
uao_thread_switch(next);
/*
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 6f42c68..cb87234 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -149,6 +149,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
* We need to tell the secondary core where to find its stack and the
* page tables.
*/
+ secondary_data.task = idle;
secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
update_cpu_boot_status(CPU_MMU_OFF);
__flush_dcache_area(&secondary_data, sizeof(secondary_data));
@@ -173,6 +174,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
}
+ secondary_data.task = NULL;
secondary_data.stack = NULL;
status = READ_ONCE(secondary_data.status);
if (ret && status) {
--
2.7.4
^ permalink raw reply related [flat|nested] 13+ messages in thread* [PATCHv2 00/11] arm64: move thread_info off of the task stack
2016-11-03 20:23 [PATCHv2 00/11] arm64: move thread_info off of the task stack Mark Rutland
` (10 preceding siblings ...)
2016-11-03 20:23 ` [PATCHv2 11/11] arm64: split thread_info from task stack Mark Rutland
@ 2016-11-14 17:50 ` Catalin Marinas
11 siblings, 0 replies; 13+ messages in thread
From: Catalin Marinas @ 2016-11-14 17:50 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, Nov 03, 2016 at 08:23:02PM +0000, Mark Rutland wrote:
> Mark Rutland (11):
> arm64: thread_info remove stale items
> arm64: asm-offsets: remove unused definitions
> arm64: factor out current_stack_pointer
> arm64: traps: simplify die() and __die()
> arm64: unexport walk_stackframe
> arm64: prep stack walkers for THREAD_INFO_IN_TASK
> arm64: move sp_el0 and tpidr_el1 into cpu_suspend_ctx
> arm64: smp: prepare for smp_processor_id() rework
> arm64: make cpu number a percpu variable
> arm64: assembler: introduce ldr_this_cpu
> arm64: split thread_info from task stack
I queued these patches for 4.10, together with the two on
core-ti-stack-split (subject to more testing).
Thanks.
--
Catalin
^ permalink raw reply [flat|nested] 13+ messages in thread