Part Number: AM6548
1. Chip
AM6548
2. Processor SDK Version:
8.4 (i forget which version exactly)
3. System
using rt-linux kernel with ubuntu rootfs
4. What happens
the following errors occasionally occur during the network sending and receiving. it's hard to reproduce.
[1296633.370657] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 [1296633.379696] Mem abort info: [1296633.382729] ESR = 0x96000006 [1296633.386005] EC = 0x25: DABT (current EL), IL = 32 bits [1296633.391517] SET = 0, FnV = 0 [1296633.394798] EA = 0, S1PTW = 0 [1296633.398194] Data abort info: [1296633.401313] ISV = 0, ISS = 0x00000006 [1296633.405336] CM = 0, WnR = 0 [1296633.408485] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000081557000 [1296633.415103] [0000000000000010] pgd=0000000092deb003, p4d=0000000092deb003, pud=0000000092ce1003, pmd=0000000000000000 [1296633.425895] Internal error: Oops: 96000006 [#1] PREEMPT_RT SMP [1296633.431893] Modules linked in: usb_storage crct10dif_ce icssg_prueth pru_swuart xhci_plat_hcd xhci_hcd pru_rproc ti_am335x_adc irq_pruss_intc kfifo_buf icss_iep spi_cadence_quadspi mcp25xx m_can_platform m_can ti_cal dwc3 ti_am335x_tscadc videobuf2_dma_contig udc_core v4l2_fwnode roles videobuf2_memops videobuf2_v4l2 pci_endpoint_test pvrsrvkm(O) pruss videobuf2_common sa2ul sha512_generic authenc phy_omap_usb2 dwc3_keystone 8250_pruss option usb_wwan usbserial usbcore usb_common em1000_spi_adc ip_tables x_tables ipv6 [1296633.477985] CPU: 0 PID: 469 Comm: irq/52-46000000 Tainted: G O 5.10.140-rt73 #1 [1296633.486756] Hardware name: Texas Instruments AM654 Base Board (DT) [1296633.493097] pstate: 40000005 (nZcv daif -PAN -UAO -TCO BTYPE=--) [1296633.499268] pc : am65_cpsw_nuss_tx_compl_packet+0x40/0x98 [1296633.504849] lr : am65_cpsw_nuss_tx_compl_packet+0x38/0x98 [1296633.510414] sp : ffff800011b4bb50 [1296633.513893] x29: ffff800011b4bb50 x28: ffff0000038cc000 [1296633.519371] x27: 00000000000005ea x26: 0000000000000000 [1296633.524849] x25: 0000000000000000 x24: ffff000000d10118 [1296633.530326] x23: ffff000000d10120 x22: ffff000000d10118 [1296633.535803] x21: 0000000000000001 x20: 0000000000000000 [1296633.541281] x19: ffff000000d10118 x18: fffffe0000328d08 [1296633.546758] x17: 00000000706e99ae x16: 00000000b0c176f1 [1296633.552237] x15: 0000000062286873 x14: 0000000000000005 [1296633.557712] x13: ffff80001199d000 x12: 0000000000000010 [1296633.563190] x11: 0000000000000001 x10: ffff80001199d048 [1296633.568666] x9 : 0000000000000000 x8 : 0001ffffffffffff [1296633.574144] x7 : fffeffffffffffff x6 : 0001000000000000 [1296633.579622] x5 : ffff80001199d048 x4 : 0000000000000000 [1296633.585098] x3 : ffff80001199d048 x2 : ffff80001199d010 [1296633.590574] x1 : 0000000000000000 x0 : ffff000000d10080 [1296633.596053] Call trace: [1296633.598668] am65_cpsw_nuss_tx_compl_packet+0x40/0x98 [1296633.603887] am65_cpsw_nuss_tx_poll+0x170/0x2c8 [1296633.608588] net_rx_action+0x13c/0x2dc [1296633.612510] efi_header_end+0x1d0/0x218 [1296633.616514] __local_bh_enable_ip+0x130/0x134 [1296633.621039] irq_forced_thread_fn+0x80/0xa4 [1296633.625393] irq_thread+0x120/0x1d0 [1296633.629049] kthread+0x120/0x130 [1296633.632448] ret_from_fork+0x10/0x30 [1296633.636202] Code: aa1303e0 97ffff83 f940c660 aa1403e1 (f9400a95) [1296633.642460] ---[ end trace 0000000000000002 ]--- [1296633.647403] Kernel panic - not syncing: [1296633.651402] Oops: Fatal exception in interrupt [1296633.651503] SMP: stopping secondary CPUs [1296633.660212] Kernel Offset: disabled [1296633.663864] CPU features: 0x0040002,2000200c [1296633.668297] Memory Limit: none [1296633.671521] ---[ end Kernel panic - not syncing: Oops: Fatal exception in interrupt ]---
5. Other
i disassemble the source file(drivers/net/ethernet/ti/am65_cpsw_nuss.c), and found that skb is null pointer in the function am65_cpsw_nuss_tx_compl_packet.
static struct sk_buff *
am65_cpsw_nuss_tx_compl_packet(struct am65_cpsw_tx_chn *tx_chn,
dma_addr_t desc_dma)
{
struct am65_cpsw_ndev_priv *ndev_priv;
struct am65_cpsw_ndev_stats *stats;
struct cppi5_host_desc_t *desc_tx;
struct net_device *ndev;
struct sk_buff *skb;
void **swdata;
desc_tx = k3_cppi_desc_pool_dma2virt(tx_chn->desc_pool,
desc_dma);
swdata = cppi5_hdesc_get_swdata(desc_tx);
skb = *(swdata); // this is a null pointer
am65_cpsw_nuss_xmit_free(tx_chn, desc_tx);
ndev = skb->dev;
am65_cpts_tx_timestamp(tx_chn->common->cpts, skb);
ndev_priv = netdev_priv(ndev);
stats = this_cpu_ptr(ndev_priv->stats);
u64_stats_update_begin(&stats->syncp);
stats->tx_packets++;
stats->tx_bytes += skb->len;
u64_stats_update_end(&stats->syncp);
return skb;
}
00000000000007e0 <am65_cpsw_nuss_tx_compl_packet>:
am65_cpsw_nuss_tx_compl_packet():
7e0: d503233f paciasp
7e4: a9bd7bfd stp x29, x30, [sp, #-48]!
7e8: 910003fd mov x29, sp
7ec: a90153f3 stp x19, x20, [sp, #16]
7f0: aa0003f3 mov x19, x0
7f4: f90013f5 str x21, [sp, #32]
7f8: f940c800 ldr x0, [x0, #400]
7fc: 94000000 bl 0 <k3_cppi_desc_pool_dma2virt>
7fc: R_AARCH64_CALL26 k3_cppi_desc_pool_dma2virt
800: aa0003e4 mov x4, x0
804: 97fffe1d bl 78 <cppi5_hdesc_get_swdata>
808: aa0403e1 mov x1, x4
80c: f9400014 ldr x20, [x0]
810: aa1303e0 mov x0, x19
814: 97ffff83 bl 620 <am65_cpsw_nuss_xmit_free>
818: f940c660 ldr x0, [x19, #392]
81c: aa1403e1 mov x1, x20
820: f9400a95 ldr x21, [x20, #16]
824: f94c0800 ldr x0, [x0, #6160]
828: 94000000 bl 0 <am65_cpts_tx_timestamp>
828: R_AARCH64_CALL26 am65_cpts_tx_timestamp
82c: f944eab3 ldr x19, [x21, #2512]
830: 94000000 bl 0 <debug_smp_processor_id>
830: R_AARCH64_CALL26 debug_smp_processor_id
834: 90000001 adrp x1, 0 <__per_cpu_offset>
834: R_AARCH64_ADR_PREL_PG_HI21 __per_cpu_offset
838: 91000021 add x1, x1, #0x0
838: R_AARCH64_ADD_ABS_LO12_NC __per_cpu_offset
83c: f8605820 ldr x0, [x1, w0, uxtw #3]
840: 8b000262 add x2, x19, x0
844: f8606a61 ldr x1, [x19, x0]
848: 91000421 add x1, x1, #0x1
84c: f8206a61 str x1, [x19, x0]
850: f9400440 ldr x0, [x2, #8]
854: b9407281 ldr w1, [x20, #112]
858: 8b010000 add x0, x0, x1
85c: f9000440 str x0, [x2, #8]
860: aa1403e0 mov x0, x20
864: a94153f3 ldp x19, x20, [sp, #16]
868: f94013f5 ldr x21, [sp, #32]
86c: a8c37bfd ldp x29, x30, [sp], #48
870: d50323bf autiasp
874: d65f03c0 ret
