Re: [PATCH v4 01/18] arm64: stacktrace: Add shared header for common stack unwinding code
From: Kalesh Singh
Date: Mon Jul 18 2022 - 11:26:35 EST
On Mon, Jul 18, 2022 at 5:52 AM Russell King (Oracle)
<linux@xxxxxxxxxxxxxxx> wrote:
>
> Hi,
>
> Can you please explain why you are targetting my @oracle.com email
> address with this patch set?
>
> This causes me problems as I use Outlook's Web interface for that
> which doesn't appear to cope with the threading, and most certainly
> is only capable of top-reply only which is against Linux kernel email
> standards.
Hi Russell,
Sorry I wasn't aware of it (I got your oracle email from
get_maintainer script). Going forward I'll use the one you responded
from instead.
Thanks,
Kalesh
>
> Thanks.
>
> On Thu, Jul 14, 2022 at 11:10:10PM -0700, Kalesh Singh wrote:
> > In order to reuse the arm64 stack unwinding logic for the nVHE
> > hypervisor stack, move the common code to a shared header
> > (arch/arm64/include/asm/stacktrace/common.h).
> >
> > The nVHE hypervisor cannot safely link against kernel code, so we
> > make use of the shared header to avoid duplicated logic later in
> > this series.
> >
> > Signed-off-by: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
> > ---
> > arch/arm64/include/asm/stacktrace.h | 35 +------
> > arch/arm64/include/asm/stacktrace/common.h | 105 +++++++++++++++++++++
> > arch/arm64/kernel/stacktrace.c | 57 -----------
> > 3 files changed, 106 insertions(+), 91 deletions(-)
> > create mode 100644 arch/arm64/include/asm/stacktrace/common.h
> >
> > diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
> > index aec9315bf156..79f455b37c84 100644
> > --- a/arch/arm64/include/asm/stacktrace.h
> > +++ b/arch/arm64/include/asm/stacktrace.h
> > @@ -8,52 +8,19 @@
> > #include <linux/percpu.h>
> > #include <linux/sched.h>
> > #include <linux/sched/task_stack.h>
> > -#include <linux/types.h>
> > #include <linux/llist.h>
> >
> > #include <asm/memory.h>
> > #include <asm/ptrace.h>
> > #include <asm/sdei.h>
> >
> > -enum stack_type {
> > - STACK_TYPE_UNKNOWN,
> > - STACK_TYPE_TASK,
> > - STACK_TYPE_IRQ,
> > - STACK_TYPE_OVERFLOW,
> > - STACK_TYPE_SDEI_NORMAL,
> > - STACK_TYPE_SDEI_CRITICAL,
> > - __NR_STACK_TYPES
> > -};
> > -
> > -struct stack_info {
> > - unsigned long low;
> > - unsigned long high;
> > - enum stack_type type;
> > -};
> > +#include <asm/stacktrace/common.h>
> >
> > extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
> > const char *loglvl);
> >
> > DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);
> >
> > -static inline bool on_stack(unsigned long sp, unsigned long size,
> > - unsigned long low, unsigned long high,
> > - enum stack_type type, struct stack_info *info)
> > -{
> > - if (!low)
> > - return false;
> > -
> > - if (sp < low || sp + size < sp || sp + size > high)
> > - return false;
> > -
> > - if (info) {
> > - info->low = low;
> > - info->high = high;
> > - info->type = type;
> > - }
> > - return true;
> > -}
> > -
> > static inline bool on_irq_stack(unsigned long sp, unsigned long size,
> > struct stack_info *info)
> > {
> > diff --git a/arch/arm64/include/asm/stacktrace/common.h b/arch/arm64/include/asm/stacktrace/common.h
> > new file mode 100644
> > index 000000000000..64ae4f6b06fe
> > --- /dev/null
> > +++ b/arch/arm64/include/asm/stacktrace/common.h
> > @@ -0,0 +1,105 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Common arm64 stack unwinder code.
> > + *
> > + * Copyright (C) 2012 ARM Ltd.
> > + */
> > +#ifndef __ASM_STACKTRACE_COMMON_H
> > +#define __ASM_STACKTRACE_COMMON_H
> > +
> > +#include <linux/bitmap.h>
> > +#include <linux/bitops.h>
> > +#include <linux/types.h>
> > +
> > +enum stack_type {
> > + STACK_TYPE_UNKNOWN,
> > + STACK_TYPE_TASK,
> > + STACK_TYPE_IRQ,
> > + STACK_TYPE_OVERFLOW,
> > + STACK_TYPE_SDEI_NORMAL,
> > + STACK_TYPE_SDEI_CRITICAL,
> > + __NR_STACK_TYPES
> > +};
> > +
> > +struct stack_info {
> > + unsigned long low;
> > + unsigned long high;
> > + enum stack_type type;
> > +};
> > +
> > +/*
> > + * A snapshot of a frame record or fp/lr register values, along with some
> > + * accounting information necessary for robust unwinding.
> > + *
> > + * @fp: The fp value in the frame record (or the real fp)
> > + * @pc: The lr value in the frame record (or the real lr)
> > + *
> > + * @stacks_done: Stacks which have been entirely unwound, for which it is no
> > + * longer valid to unwind to.
> > + *
> > + * @prev_fp: The fp that pointed to this frame record, or a synthetic value
> > + * of 0. This is used to ensure that within a stack, each
> > + * subsequent frame record is at an increasing address.
> > + * @prev_type: The type of stack this frame record was on, or a synthetic
> > + * value of STACK_TYPE_UNKNOWN. This is used to detect a
> > + * transition from one stack to another.
> > + *
> > + * @kr_cur: When KRETPROBES is selected, holds the kretprobe instance
> > + * associated with the most recently encountered replacement lr
> > + * value.
> > + *
> > + * @task: The task being unwound.
> > + */
> > +struct unwind_state {
> > + unsigned long fp;
> > + unsigned long pc;
> > + DECLARE_BITMAP(stacks_done, __NR_STACK_TYPES);
> > + unsigned long prev_fp;
> > + enum stack_type prev_type;
> > +#ifdef CONFIG_KRETPROBES
> > + struct llist_node *kr_cur;
> > +#endif
> > + struct task_struct *task;
> > +};
> > +
> > +static inline bool on_stack(unsigned long sp, unsigned long size,
> > + unsigned long low, unsigned long high,
> > + enum stack_type type, struct stack_info *info)
> > +{
> > + if (!low)
> > + return false;
> > +
> > + if (sp < low || sp + size < sp || sp + size > high)
> > + return false;
> > +
> > + if (info) {
> > + info->low = low;
> > + info->high = high;
> > + info->type = type;
> > + }
> > + return true;
> > +}
> > +
> > +static inline void unwind_init_common(struct unwind_state *state,
> > + struct task_struct *task)
> > +{
> > + state->task = task;
> > +#ifdef CONFIG_KRETPROBES
> > + state->kr_cur = NULL;
> > +#endif
> > +
> > + /*
> > + * Prime the first unwind.
> > + *
> > + * In unwind_next() we'll check that the FP points to a valid stack,
> > + * which can't be STACK_TYPE_UNKNOWN, and the first unwind will be
> > + * treated as a transition to whichever stack that happens to be. The
> > + * prev_fp value won't be used, but we set it to 0 such that it is
> > + * definitely not an accessible stack address.
> > + */
> > + bitmap_zero(state->stacks_done, __NR_STACK_TYPES);
> > + state->prev_fp = 0;
> > + state->prev_type = STACK_TYPE_UNKNOWN;
> > +}
> > +
> > +#endif /* __ASM_STACKTRACE_COMMON_H */
> > diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
> > index fcaa151b81f1..94a5dd2ab8fd 100644
> > --- a/arch/arm64/kernel/stacktrace.c
> > +++ b/arch/arm64/kernel/stacktrace.c
> > @@ -18,63 +18,6 @@
> > #include <asm/stack_pointer.h>
> > #include <asm/stacktrace.h>
> >
> > -/*
> > - * A snapshot of a frame record or fp/lr register values, along with some
> > - * accounting information necessary for robust unwinding.
> > - *
> > - * @fp: The fp value in the frame record (or the real fp)
> > - * @pc: The lr value in the frame record (or the real lr)
> > - *
> > - * @stacks_done: Stacks which have been entirely unwound, for which it is no
> > - * longer valid to unwind to.
> > - *
> > - * @prev_fp: The fp that pointed to this frame record, or a synthetic value
> > - * of 0. This is used to ensure that within a stack, each
> > - * subsequent frame record is at an increasing address.
> > - * @prev_type: The type of stack this frame record was on, or a synthetic
> > - * value of STACK_TYPE_UNKNOWN. This is used to detect a
> > - * transition from one stack to another.
> > - *
> > - * @kr_cur: When KRETPROBES is selected, holds the kretprobe instance
> > - * associated with the most recently encountered replacement lr
> > - * value.
> > - *
> > - * @task: The task being unwound.
> > - */
> > -struct unwind_state {
> > - unsigned long fp;
> > - unsigned long pc;
> > - DECLARE_BITMAP(stacks_done, __NR_STACK_TYPES);
> > - unsigned long prev_fp;
> > - enum stack_type prev_type;
> > -#ifdef CONFIG_KRETPROBES
> > - struct llist_node *kr_cur;
> > -#endif
> > - struct task_struct *task;
> > -};
> > -
> > -static void unwind_init_common(struct unwind_state *state,
> > - struct task_struct *task)
> > -{
> > - state->task = task;
> > -#ifdef CONFIG_KRETPROBES
> > - state->kr_cur = NULL;
> > -#endif
> > -
> > - /*
> > - * Prime the first unwind.
> > - *
> > - * In unwind_next() we'll check that the FP points to a valid stack,
> > - * which can't be STACK_TYPE_UNKNOWN, and the first unwind will be
> > - * treated as a transition to whichever stack that happens to be. The
> > - * prev_fp value won't be used, but we set it to 0 such that it is
> > - * definitely not an accessible stack address.
> > - */
> > - bitmap_zero(state->stacks_done, __NR_STACK_TYPES);
> > - state->prev_fp = 0;
> > - state->prev_type = STACK_TYPE_UNKNOWN;
> > -}
> > -
> > /*
> > * Start an unwind from a pt_regs.
> > *
> > --
> > 2.37.0.170.g444d1eabd0-goog
> >
> >
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> > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> >
>
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