On Tue, 16 Oct 2018 17:08:25 +0530 Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx> wrote: > Hi, > > On dragonboard 410c, with "ftrace=function" boot args, the console > output slows down and board resets without any backtrace as below. This > is tested on latest kernel and seems to exist even in older kernels as well. So this only happens when ftrace=function is on the boot console. > > [ 2.949164] EINJ: ACPI disabled. > [ 3.133001] Serial: 8250/16550 dri > Format: Log Type - Time(microsec) - Message - Optional Info > Log Type: B - Since Boot(Power On Reset), D - Delta, S - Statistic > > But with pstore enabled, able to get the below backtrace: > > <4>[ 2.949164] EINJ: ACPI disabled. > <6>[ 3.133001] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled > <6>[ 3.164097] SuperH (H)SCI(F) driver initialized > <0>[ 3.164471] Internal error: synchronous external abort: 96000010 > [#1] PREEMPT SMP > <4>[ 3.164479] Modules linked in: > <4>[ 3.164495] CPU: 2 PID: 1 Comm: swapper/0 Not tainted > 4.19.0-rc8-00008-ge033b9909fff-dirty #175 > <4>[ 3.164501] Hardware name: Qualcomm Technologies, Inc. APQ 8016 > SBC (DT) > <4>[ 3.164508] pstate: 40000085 (nZcv daIf -PAN -UAO) > <4>[ 3.164514] pc : msm_read.isra.2+0x20/0x50 > <4>[ 3.164520] lr : msm_read.isra.2+0x1c/0x50 > <4>[ 3.164526] sp : ffff000008033a50 > <4>[ 3.164531] x29: ffff000008033a50 x28: ffff000009486018 > <4>[ 3.164548] x27: 0000000000000001 x26: ffff7dfffe7ff070 > <4>[ 3.164565] x25: 0000000000000034 x24: ffff000009486000 > <4>[ 3.164582] x23: 0000000000000000 x22: ffff00000978e190 > <4>[ 3.164599] x21: ffff0000095e8228 x20: 0000000000000034 > <4>[ 3.164616] x19: ffff7dfffe7ff008 x18: ffffffffffffffff > <4>[ 3.164632] x17: 0000000000000000 x16: 0000000000000000 > <4>[ 3.164649] x15: ffff0000094a96c8 x14: ffff00008978e6bf > <4>[ 3.164666] x13: ffff00000978e6cd x12: 0000000000000038 > <4>[ 3.164683] x11: ffff0000094c6000 x10: 0000000000000c24 > <4>[ 3.164699] x9 : ffff80003c89b400 x8 : ffff000008033970 > <4>[ 3.164716] x7 : ffff80000eb04100 x6 : 00000000000af304 > <4>[ 3.164732] x5 : 0000000000000c40 x4 : ffff80003c06f000 > <4>[ 3.164750] x3 : ffff80003c89b498 x2 : 0000000000000000 > <4>[ 3.164766] x1 : ffff80003ca68000 x0 : 0000000000000800 > <0>[ 3.164785] Process swapper/0 (pid: 1, stack limit = > 0x(____ptrval____)) > <4>[ 3.164791] Call trace: > <4>[ 3.164797] msm_read.isra.2+0x20/0x50 > <4>[ 3.164804] msm_reset_dm_count+0x44/0x80 > <4>[ 3.164810] __msm_console_write+0x1c8/0x1d0 > <4>[ 3.164816] msm_serial_early_write_dm+0x3c/0x50 > <4>[ 3.164823] console_unlock.part.6+0x468/0x528 > <4>[ 3.164829] vprintk_emit+0x210/0x218 > <4>[ 3.164835] vprintk_default+0x48/0x58 > <4>[ 3.164841] vprintk_func+0xf0/0x1c0 > <4>[ 3.164847] printk+0x74/0x94 > <4>[ 3.164853] sci_init+0x24/0x3c > <4>[ 3.164859] do_one_initcall+0x54/0x248 > <4>[ 3.164866] kernel_init_freeable+0x210/0x378 > <4>[ 3.164872] kernel_init+0x18/0x118 > <4>[ 3.164878] ret_from_fork+0x10/0x1c > <0>[ 3.164884] Code: aa1e03e0 8b214273 97e616f7 d503201f (b9400260) > > Seems to be issue with the msm serial driver and not ftrace. > Could someone look into it. I'm guessing that there may have been an issue with ftrace, it tried to print, but the printing caused a bug that rebooted the box. Does function tracing work after boot up? That is, without the ftrace=function, can you do: echo function > /sys/kernel/debug/tracing/current_tracer without any issue? > > One more thing is for pstore dmesg-ramoops, I had to change > late_initcall to postcore_initcall which brings the question as to why > we changed to late_initcall? > Simple git blame shows to support crypto compress api, but is it really > helpful? A lot of boottime issues can be caught with pstore enabled at > postcore_initcall rather than late_initcall, this backtrace > is just one example. Is there any way we could change this? Does it break if the crypto is not initialized? Perhaps add a command line flag to have it happen earlier: ramoops=earlyinit and add a postcore_initcall that checks if that flag is set, and if so, it does the work then, and the late_initcall() will do nothing. That way, you can still have unmodified kernels use pstore when it crashes at boot up. -- Steve
