linux/arch/arm/kernel/return_address.c, branch v7.0

ARM: 9258/1: stacktrace: Make stack walk callback consistent with generic code

2022-11-08T18:36:18Z

As with the generic arch_stack_walk() code the ARM stack walk code takes a callback that is called per stack frame. Currently the ARM code always passes a struct stackframe to the callback and the generic code just passes the pc, however none of the users ever reference anything in the struct other than the pc value. The ARM code also uses a return type of int while the generic code uses a return type of bool though in both cases the return value is a boolean value and the sense is inverted between the two. In order to reduce code duplication when ARM is converted to use arch_stack_walk() change the signature and return sense of the ARM specific callback to match that of the generic code. Signed-off-by: Li Huafei Reviewed-by: Mark Brown Reviewed-by: Linus Waleij Signed-off-by: Russell King (Oracle)

ARM: 9234/1: stacktrace: Avoid duplicate saving of exception PC value

2022-10-04T10:09:47Z

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 Reviewed-by: Linus Waleij Signed-off-by: Russell King (Oracle)

ARM: unwind: set frame.pc correctly for current-thread unwinding

2022-03-11T10:55:28Z

When e.g. a WARN_ON() is encountered, we attempt to unwind the current thread. To do this, we set frame.pc to unwind_backtrace, which means it points at the beginning of the function. However, the rest of the state is initialised from within the function, which means the function prologue has already been run. This can be confusing, and with a recent patch from Ard, can result in the unwinder misbehaving if we want to be strict about the PC value. If we correctly initialise the state so it is self-consistent (in other words, set frame.pc to the location we are initialising it) then we eliminate this confusion, and avoid possible future issues. Reviewed-by: Ard Biesheuvel Signed-off-by: Russell King (Oracle)

ARM: Recover kretprobe modified return address in stacktrace

2021-10-22T16:16:53Z

Since the kretprobe replaces the function return address with the kretprobe_trampoline on the stack, arm unwinder shows it instead of the correct return address. This finds the correct return address from the per-task kretprobe_instances list and verify it is in between the caller fp and callee fp. Note that this supports both GCC and clang if CONFIG_FRAME_POINTER=y and CONFIG_ARM_UNWIND=n. For the ARM unwinder, this is still not working correctly. Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

ARM: 8918/2: only build return_address() if needed

2019-11-15T22:21:07Z

The system currently warns if the config conditions for building return_address in arch/arm/kernel/return_address.c are not met, leaving just an EXPORT_SYMBOL_GPL(return_address) of a function defined to be 'static linline'. This is a result of aeea3592a13b ("ARM: 8158/1: LLVMLinux: use static inline in ARM ftrace.h"). Since we're not going to build anything other than an exported symbol for something that is already being defined to be an inline-able return of NULL, just avoid building the code to remove the following warning: Fixes: aeea3592a13b ("ARM: 8158/1: LLVMLinux: use static inline in ARM ftrace.h") Signed-off-by: Ben Dooks Signed-off-by: Russell King

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55Z

Based on 2 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Enrico Weigelt Reviewed-by: Kate Stewart Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman

ARM: 8328/1: remove empty preprocessor #else branch

2015-03-28T16:54:53Z

When the patch for e16343c47e42 (ARM: 8160/1: drop warning about return_address not using unwind tables) was created there was still more code in said branch. Probably this simplification was just missed during conflict resolution when the patch was applied. Signed-off-by: Uwe Kleine-König Signed-off-by: Russell King

ARM: 8171/1: Use current_stack_pointer for return_address

2014-11-13T23:58:01Z

Use the global current_stack_pointer to get the value of the stack pointer. This change supports being able to compile the kernel with both gcc and Clang. Signed-off-by: Behan Webster Reviewed-by: Mark Charlebois Reviewed-by: Jan-Simon Möller Acked-by: Will Deacon Acked-by: Nicolas Pitre Signed-off-by: Russell King

ARM: 8160/1: drop warning about return_address not using unwind tables

2014-09-26T13:40:07Z

The warning was introduced in 2009 (commit 4bf1fa5a34aa ([ARM] 5613/1: implement CALLER_ADDRESSx)). The only "problem" here is that CALLER_ADDRESSx for x > 1 returns NULL which doesn't do much harm. The drawback of implementing a fix (i.e. use unwind tables to implement CALLER_ADDRESSx) is that much of the unwinder code would need to be marked as not traceable. Signed-off-by: Uwe Kleine-König Signed-off-by: Russell King

ARM: 8158/1: LLVMLinux: use static inline in ARM ftrace.h

2014-09-26T13:40:03Z

With compilers which follow the C99 standard (like modern versions of gcc and clang), "extern inline" does the wrong thing (emits code for an externally linkable version of the inline function). In this case using static inline and removing the NULL version of return_address in return_address.c does the right thing. Signed-off-by: Behan Webster Reviewed-by: Mark Charlebois Acked-by: Steven Rostedt Signed-off-by: Russell King