752ec621ef
Because an exception stack frame is not created in the exception entry,
save_trace() does special handling for the exception PC, but this is
only needed when CONFIG_FRAME_POINTER_UNWIND=y. When
CONFIG_ARM_UNWIND=y, unwind annotations have been added to the exception
entry and save_trace() will repeatedly save the exception PC:
[0x7f000090] hrtimer_hander+0x8/0x10 [hrtimer]
[0x8019ec50] __hrtimer_run_queues+0x18c/0x394
[0x8019f760] hrtimer_run_queues+0xbc/0xd0
[0x8019def0] update_process_times+0x34/0x80
[0x801ad2a4] tick_periodic+0x48/0xd0
[0x801ad3dc] tick_handle_periodic+0x1c/0x7c
[0x8010f2e0] twd_handler+0x30/0x40
[0x80177620] handle_percpu_devid_irq+0xa0/0x23c
[0x801718d0] generic_handle_domain_irq+0x24/0x34
[0x80502d28] gic_handle_irq+0x74/0x88
[0x8085817c] generic_handle_arch_irq+0x58/0x78
[0x80100ba8] __irq_svc+0x88/0xc8
[0x80108114] arch_cpu_idle+0x38/0x3c
[0x80108114] arch_cpu_idle+0x38/0x3c <==== duplicate saved exception PC
[0x80861bf8] default_idle_call+0x38/0x130
[0x8015d5cc] do_idle+0x150/0x214
[0x8015d978] cpu_startup_entry+0x18/0x1c
[0x808589c0] rest_init+0xd8/0xdc
[0x80c00a44] arch_post_acpi_subsys_init+0x0/0x8
We can move the special handling of the exception PC in save_trace() to
the unwind_frame() of the frame pointer unwinder.
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Reviewed-by: Linus Waleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.