* Exception in function_graph tracing @ 2022-09-13 19:21 Danilo Cezar Zanella 2022-09-16 20:05 ` Sebastian Andrzej Siewior 0 siblings, 1 reply; 5+ messages in thread From: Danilo Cezar Zanella @ 2022-09-13 19:21 UTC (permalink / raw) To: linux-rt-users Hi I'm getting the following error message when I set the current_tracer to function_graph. Procedures: cd / sys/kernel/tracing echo function_graph > current_tracer Then I saw the following message in the console. Unable to handle kernel paging request at virtual address fffffffc ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at kernel/sched/core.c:7270 migrate_disable+0x104/0x114 Modules linked in: rtc_armada38x ts7800_v2_wdt spi_orion spi_gpio i2c_gpio i2c_algo_bit CPU: 0 PID: 0 Comm: Not tainted 4.19.249-rt111-llama-rt+ #36 Hardware name: Marvell Armada 380/385 (Device Tree) [<c011424c>] (unwind_backtrace) from [<c010e318>] (show_stack+0x18/0x1c) [<c010e318>] (show_stack) from [<c09da8ac>] (dump_stack+0x84/0x98) [<c09da8ac>] (dump_stack) from [<c0124bc8>] (__warn+0x100/0x118) [<c0124bc8>] (__warn) from [<c0124d0c>] (warn_slowpath_null+0x48/0x50) [<c0124d0c>] (warn_slowpath_null) from [<c015163c>] (migrate_disable+0x104/0x114) [<c015163c>] (migrate_disable) from [<c0182920>] (vprintk_emit+0x10c/0x1ec) [<c0182920>] (vprintk_emit) from [<c0182bc0>] (vprintk_default+0x28/0x30) [<c0182bc0>] (vprintk_default) from [<c09d5100>] (printk+0x38/0x5c) [<c09d5100>] (printk) from [<c09d4dc8>] (__do_kernel_fault.part.0+0x4c/0x7c) [<c09d4dc8>] (__do_kernel_fault.part.0) from [<c0118d84>] (do_page_fault+0x380/0x394) [<c0118d84>] (do_page_fault) from [<c0118f6c>] (do_DataAbort+0x50/0xf0) ---[ end trace 0000000000000002 ]--- pgd = 721da14e [fffffffc] *pgd=2fffd861, *pte=00000000, *ppte=00000000 Internal error: Oops: 37 [#1] PREEMPT SMP ARM Modules linked in: rtc_armada38x ts7800_v2_wdt spi_orion spi_gpio i2c_gpio i2c_algo_bit CPU: 0 PID: 0 Comm: Tainted: G W 4.19.249-rt111-llama-rt+ #36 Hardware name: Marvell Armada 380/385 (Device Tree) PC is at prepare_ftrace_return+0x20/0x48 LR is at ftrace_graph_caller+0x18/0x20 pc : [<c0112884>] lr : [<c0112540>] psr: 600f0193 sp : ef12a090 ip : 00000051 fp : 00000000 r10: e9c61d7c r9 : ef12a000 r8 : 00000001 r7 : ef12a19c r6 : ffffffff r5 : 600f0193 r4 : c0112884 r3 : 00000000 r2 : 00000000 r1 : c0118f28 r0 : fffffffc Flags: nZCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment none Control: 10c5387d Table: 29c7004a DAC: 00000051 Process (pid: 0, stack limit = 0x6b08bd12) Stack: (0xef12a090 to 0xef07651c) [<c0112884>] (prepare_ftrace_return) from [<c0112540>] (ftrace_graph_caller+0x18/0x20) Code: e5933010 e593366c e3530000 18bd8070 (e5905000) ---[ end trace 0000000000000003 ]--- Kernel panic - not syncing: Attempted to kill the idle task! SMP: failed to stop secondary CPUs What is going on? Am I doing something wrong? Thanks Danilo ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Exception in function_graph tracing 2022-09-13 19:21 Exception in function_graph tracing Danilo Cezar Zanella @ 2022-09-16 20:05 ` Sebastian Andrzej Siewior [not found] ` <CAAxUTH4xawCFpnwpRkcaZ5fdzMEbZZmPOyVDoqdMrPrf+G64dg@mail.gmail.com> 0 siblings, 1 reply; 5+ messages in thread From: Sebastian Andrzej Siewior @ 2022-09-16 20:05 UTC (permalink / raw) To: Danilo Cezar Zanella; +Cc: linux-rt-users On 2022-09-13 16:21:27 [-0300], Danilo Cezar Zanella wrote: > Hi Hi, > I'm getting the following error message when I set the current_tracer > to function_graph. Procedures: > > cd / sys/kernel/tracing > echo function_graph > current_tracer > > Then I saw the following message in the console. > > Unable to handle kernel paging request at virtual address fffffffc … > What is going on? > Am I doing something wrong? No, not as far I can tell. It looks like the function_graph tracer is busted in v4.19 even without the PREEMPT_RT patch. The function tracer seems to work. > Thanks > > Danilo Sebastian ^ permalink raw reply [flat|nested] 5+ messages in thread
[parent not found: <CAAxUTH4xawCFpnwpRkcaZ5fdzMEbZZmPOyVDoqdMrPrf+G64dg@mail.gmail.com>]
* Re: Exception in function_graph tracing [not found] ` <CAAxUTH4xawCFpnwpRkcaZ5fdzMEbZZmPOyVDoqdMrPrf+G64dg@mail.gmail.com> @ 2022-09-27 11:06 ` Sebastian Andrzej Siewior 2022-10-05 8:43 ` [PATCH] ARM: fix function graph tracer and unwinder dependencies Sebastian Andrzej Siewior 0 siblings, 1 reply; 5+ messages in thread From: Sebastian Andrzej Siewior @ 2022-09-27 11:06 UTC (permalink / raw) To: Danilo Cezar Zanella; +Cc: linux-rt-users On 2022-09-16 17:28:00 [-0300], Danilo Cezar Zanella wrote: > Hi Sebastian, Hi Danilo, please don't lose the list. > > No, not as far I can tell. > It sounds good. ;-) > > > It looks like the function_graph tracer is busted in v4.19 even without the PREEMPT_RT patch. > It sounds bad... :-( > > I'm new in LKM development and even more in Kernel tracing. > I've tested 'nop' and 'function' tracing, both seem to work. Do you > know when this issue was solved? Perhaps could I do a backport of > it(if it is easy, of course)? I managed to reproduce it on v4.19 but on v6.0-rcX. So it must have been fixed somehow in between. I browsed the history but I did not notice anything obvious. So someone needs to dig deeper… > Thank you again > > Danilo Sebastian ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] ARM: fix function graph tracer and unwinder dependencies 2022-09-27 11:06 ` Sebastian Andrzej Siewior @ 2022-10-05 8:43 ` Sebastian Andrzej Siewior 2022-10-05 16:43 ` Greg KH 0 siblings, 1 reply; 5+ messages in thread From: Sebastian Andrzej Siewior @ 2022-10-05 8:43 UTC (permalink / raw) To: stable Cc: linux-rt-users, Danilo Cezar Zanella, Masami Hiramatsu, Russell King, Thomas Gleixner Danilo Cezar Zanella reported broken function graph tracer in the v4.19 tree. This was caused by the backport of commit f9b58e8c7d031 ("ARM: 8800/1: use choice for kernel unwinders") which ended in the v4.19-stable tree as of v4.19.222. It is also part of v4.14-stable since v4.14.259. It is also part of v4.9-stable since v4.9.299. ------->8--------- From: Russell King <rmk+kernel@armlinux.org.uk> Date: Tue, 23 Apr 2019 17:09:38 +0100 Subject: [PATCH] ARM: fix function graph tracer and unwinder dependencies Upstream commit 503621628b32782a07b2318e4112bd4372aa3401 Naresh Kamboju recently reported that the function-graph tracer crashes on ARM. The function-graph tracer assumes that the kernel is built with frame pointers. We explicitly disabled the function-graph tracer when building Thumb2, since the Thumb2 ABI doesn't have frame pointers. We recently changed the way the unwinder method was selected, which seems to have made it more likely that we can end up with the function- graph tracer enabled but without the kernel built with frame pointers. Fix up the function graph tracer dependencies so the option is not available when we have no possibility of having frame pointers, and adjust the dependencies on the unwinder option to hide the non-frame pointer unwinder options if the function-graph tracer is enabled. Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Tested-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reported-by: Danilo Cezar Zanella <danilo.zanella@iag.usp.br> --- arch/arm/Kconfig | 2 +- arch/arm/Kconfig.debug | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index d89d013f586cb..fce7e85f3ef57 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -68,7 +68,7 @@ config ARM select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU select HAVE_EXIT_THREAD select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL) - select HAVE_FUNCTION_GRAPH_TRACER if (!THUMB2_KERNEL) + select HAVE_FUNCTION_GRAPH_TRACER if (!THUMB2_KERNEL && !CC_IS_CLANG) select HAVE_FUNCTION_TRACER if (!XIP_KERNEL) select HAVE_FUTEX_CMPXCHG if FUTEX select HAVE_GCC_PLUGINS diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug index 01c760929c9e4..b931fac129a1b 100644 --- a/arch/arm/Kconfig.debug +++ b/arch/arm/Kconfig.debug @@ -47,8 +47,8 @@ config DEBUG_WX choice prompt "Choose kernel unwinder" - default UNWINDER_ARM if AEABI && !FUNCTION_GRAPH_TRACER - default UNWINDER_FRAME_POINTER if !AEABI || FUNCTION_GRAPH_TRACER + default UNWINDER_ARM if AEABI + default UNWINDER_FRAME_POINTER if !AEABI help This determines which method will be used for unwinding kernel stack traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack, @@ -65,7 +65,7 @@ config UNWINDER_FRAME_POINTER config UNWINDER_ARM bool "ARM EABI stack unwinder" - depends on AEABI + depends on AEABI && !FUNCTION_GRAPH_TRACER select ARM_UNWIND help This option enables stack unwinding support in the kernel -- 2.37.2 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] ARM: fix function graph tracer and unwinder dependencies 2022-10-05 8:43 ` [PATCH] ARM: fix function graph tracer and unwinder dependencies Sebastian Andrzej Siewior @ 2022-10-05 16:43 ` Greg KH 0 siblings, 0 replies; 5+ messages in thread From: Greg KH @ 2022-10-05 16:43 UTC (permalink / raw) To: Sebastian Andrzej Siewior Cc: stable, linux-rt-users, Danilo Cezar Zanella, Masami Hiramatsu, Russell King, Thomas Gleixner On Wed, Oct 05, 2022 at 10:43:34AM +0200, Sebastian Andrzej Siewior wrote: > Danilo Cezar Zanella reported broken function graph tracer in the v4.19 > tree. This was caused by the backport of commit > f9b58e8c7d031 ("ARM: 8800/1: use choice for kernel unwinders") > > which ended in the v4.19-stable tree as of v4.19.222. > It is also part of v4.14-stable since v4.14.259. > It is also part of v4.9-stable since v4.9.299. > Now queued up, thanks. greg k-h ^ permalink raw reply [flat|nested] 5+ messages in thread
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2022-09-13 19:21 Exception in function_graph tracing Danilo Cezar Zanella
2022-09-16 20:05 ` Sebastian Andrzej Siewior
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2022-09-27 11:06 ` Sebastian Andrzej Siewior
2022-10-05 8:43 ` [PATCH] ARM: fix function graph tracer and unwinder dependencies Sebastian Andrzej Siewior
2022-10-05 16:43 ` Greg KH
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