Messages in this thread | | | Subject | Re: Crash in msm serial on dragonboard with ftrace bootargs | From | Sai Prakash Ranjan <> | Date | Wed, 17 Oct 2018 17:23:54 +0530 |
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On 10/17/2018 4:39 AM, Joel Fernandes wrote: > On Tue, Oct 16, 2018 at 05:08:25PM +0530, Sai Prakash Ranjan 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. >> >> [ 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. >> >> 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? > > Any chance you are able to dig deeper into the stack trace? I would > disassemble vmlinux and see which part of msm_read is generating the > synchronous external abort and look into that. >
Yes I had checked the part of msm_read which was generating the abort and it always seems to be in "msm_wait_for_xmitr" at below pointed location.
static inline void msm_wait_for_xmitr(struct uart_port *port) { while (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY)) { <--- if (msm_read(port, UART_ISR) & UART_ISR_TX_READY) break; udelay(1); } msm_write(port, UART_CR_CMD_RESET_TX_READY, UART_CR); }
Also I could confirm that this path is entered repeatedly(with tracing register reads/writes from my patch series in https://lore.kernel.org/patchwork/cover/983795/ and tp_printk) and crash is seen at some random time, so could not get much from this.
> Also similar to what Steve suggested, I wonder if it boots for you if you > annotate all the functions in the serial driver with 'notrace'. >
I have tried this too, but still the target crashes. So I am doubtful if this is ftrace issue? Maybe earlycon uart issue as Stephen is suspecting.
Thanks, Sai
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