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Date: Wed, 12 Apr 2023 17:24:37 -0700
From: Jacob Keller <jacob.e.keller@...el.com>
To: Roman Gushchin <roman.gushchin@...ux.dev>, <netdev@...r.kernel.org>
CC: Nicolas Ferre <nicolas.ferre@...rochip.com>,
Claudiu Beznea <claudiu.beznea@...rochip.com>,
"David S . Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
"Paolo Abeni" <pabeni@...hat.com>,
Rafal Ozieblo <rafalo@...ence.com>,
Harini Katakam <harini.katakam@...inx.com>,
<linux-kernel@...r.kernel.org>,
"Lars-Peter Clausen" <lars@...afoo.de>
Subject: Re: [PATCH net v2] net: macb: fix a memory corruption in extended
buffer descriptor mode
On 4/12/2023 4:21 PM, Roman Gushchin wrote:
> For quite some time we were chasing a bug which looked like a sudden
> permanent failure of networking and mmc on some of our devices.
> The bug was very sensitive to any software changes and even more to
> any kernel debug options.
>
> Finally we got a setup where the problem was reproducible with
> CONFIG_DMA_API_DEBUG=y and it revealed the issue with the rx dma:
>
> [ 16.992082] ------------[ cut here ]------------
> [ 16.996779] DMA-API: macb ff0b0000.ethernet: device driver tries to free DMA memory it has not allocated [device address=0x0000000875e3e244] [size=1536 bytes]
> [ 17.011049] WARNING: CPU: 0 PID: 85 at kernel/dma/debug.c:1011 check_unmap+0x6a0/0x900
> [ 17.018977] Modules linked in: xxxxx
> [ 17.038823] CPU: 0 PID: 85 Comm: irq/55-8000f000 Not tainted 5.4.0 #28
> [ 17.045345] Hardware name: xxxxx
> [ 17.049528] pstate: 60000005 (nZCv daif -PAN -UAO)
> [ 17.054322] pc : check_unmap+0x6a0/0x900
> [ 17.058243] lr : check_unmap+0x6a0/0x900
> [ 17.062163] sp : ffffffc010003c40
> [ 17.065470] x29: ffffffc010003c40 x28: 000000004000c03c
> [ 17.070783] x27: ffffffc010da7048 x26: ffffff8878e38800
> [ 17.076095] x25: ffffff8879d22810 x24: ffffffc010003cc8
> [ 17.081407] x23: 0000000000000000 x22: ffffffc010a08750
> [ 17.086719] x21: ffffff8878e3c7c0 x20: ffffffc010acb000
> [ 17.092032] x19: 0000000875e3e244 x18: 0000000000000010
> [ 17.097343] x17: 0000000000000000 x16: 0000000000000000
> [ 17.102647] x15: ffffff8879e4a988 x14: 0720072007200720
> [ 17.107959] x13: 0720072007200720 x12: 0720072007200720
> [ 17.113261] x11: 0720072007200720 x10: 0720072007200720
> [ 17.118565] x9 : 0720072007200720 x8 : 000000000000022d
> [ 17.123869] x7 : 0000000000000015 x6 : 0000000000000098
> [ 17.129173] x5 : 0000000000000000 x4 : 0000000000000000
> [ 17.134475] x3 : 00000000ffffffff x2 : ffffffc010a1d370
> [ 17.139778] x1 : b420c9d75d27bb00 x0 : 0000000000000000
> [ 17.145082] Call trace:
> [ 17.147524] check_unmap+0x6a0/0x900
> [ 17.151091] debug_dma_unmap_page+0x88/0x90
> [ 17.155266] gem_rx+0x114/0x2f0
> [ 17.158396] macb_poll+0x58/0x100
> [ 17.161705] net_rx_action+0x118/0x400
> [ 17.165445] __do_softirq+0x138/0x36c
> [ 17.169100] irq_exit+0x98/0xc0
> [ 17.172234] __handle_domain_irq+0x64/0xc0
> [ 17.176320] gic_handle_irq+0x5c/0xc0
> [ 17.179974] el1_irq+0xb8/0x140
> [ 17.183109] xiic_process+0x5c/0xe30
> [ 17.186677] irq_thread_fn+0x28/0x90
> [ 17.190244] irq_thread+0x208/0x2a0
> [ 17.193724] kthread+0x130/0x140
> [ 17.196945] ret_from_fork+0x10/0x20
> [ 17.200510] ---[ end trace 7240980785f81d6f ]---
>
> [ 237.021490] ------------[ cut here ]------------
> [ 237.026129] DMA-API: exceeded 7 overlapping mappings of cacheline 0x0000000021d79e7b
> [ 237.033886] WARNING: CPU: 0 PID: 0 at kernel/dma/debug.c:499 add_dma_entry+0x214/0x240
> [ 237.041802] Modules linked in: xxxxx
> [ 237.061637] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 5.4.0 #28
> [ 237.068941] Hardware name: xxxxx
> [ 237.073116] pstate: 80000085 (Nzcv daIf -PAN -UAO)
> [ 237.077900] pc : add_dma_entry+0x214/0x240
> [ 237.081986] lr : add_dma_entry+0x214/0x240
> [ 237.086072] sp : ffffffc010003c30
> [ 237.089379] x29: ffffffc010003c30 x28: ffffff8878a0be00
> [ 237.094683] x27: 0000000000000180 x26: ffffff8878e387c0
> [ 237.099987] x25: 0000000000000002 x24: 0000000000000000
> [ 237.105290] x23: 000000000000003b x22: ffffffc010a0fa00
> [ 237.110594] x21: 0000000021d79e7b x20: ffffffc010abe600
> [ 237.115897] x19: 00000000ffffffef x18: 0000000000000010
> [ 237.121201] x17: 0000000000000000 x16: 0000000000000000
> [ 237.126504] x15: ffffffc010a0fdc8 x14: 0720072007200720
> [ 237.131807] x13: 0720072007200720 x12: 0720072007200720
> [ 237.137111] x11: 0720072007200720 x10: 0720072007200720
> [ 237.142415] x9 : 0720072007200720 x8 : 0000000000000259
> [ 237.147718] x7 : 0000000000000001 x6 : 0000000000000000
> [ 237.153022] x5 : ffffffc010003a20 x4 : 0000000000000001
> [ 237.158325] x3 : 0000000000000006 x2 : 0000000000000007
> [ 237.163628] x1 : 8ac721b3a7dc1c00 x0 : 0000000000000000
> [ 237.168932] Call trace:
> [ 237.171373] add_dma_entry+0x214/0x240
> [ 237.175115] debug_dma_map_page+0xf8/0x120
> [ 237.179203] gem_rx_refill+0x190/0x280
> [ 237.182942] gem_rx+0x224/0x2f0
> [ 237.186075] macb_poll+0x58/0x100
> [ 237.189384] net_rx_action+0x118/0x400
> [ 237.193125] __do_softirq+0x138/0x36c
> [ 237.196780] irq_exit+0x98/0xc0
> [ 237.199914] __handle_domain_irq+0x64/0xc0
> [ 237.204000] gic_handle_irq+0x5c/0xc0
> [ 237.207654] el1_irq+0xb8/0x140
> [ 237.210789] arch_cpu_idle+0x40/0x200
> [ 237.214444] default_idle_call+0x18/0x30
> [ 237.218359] do_idle+0x200/0x280
> [ 237.221578] cpu_startup_entry+0x20/0x30
> [ 237.225493] rest_init+0xe4/0xf0
> [ 237.228713] arch_call_rest_init+0xc/0x14
> [ 237.232714] start_kernel+0x47c/0x4a8
> [ 237.236367] ---[ end trace 7240980785f81d70 ]---
>
> Lars was fast to find an explanation: according to the datasheet
> bit 2 of the rx buffer descriptor entry has a different meaning in the
> extended mode:
> Address [2] of beginning of buffer, or
> in extended buffer descriptor mode (DMA configuration register [28] = 1),
> indicates a valid timestamp in the buffer descriptor entry.
>
> The macb driver didn't mask this bit while getting an address and it
> eventually caused a memory corruption and a dma failure.
>
> The problem is resolved by explicitly clearing the problematic bit
> if hw timestamping is used.
>
> Fixes: 7b4296148066 ("net: macb: Add support for PTP timestamps in DMA descriptors")
> Signed-off-by: Roman Gushchin <roman.gushchin@...ux.dev>
> Co-developed-by: Lars-Peter Clausen <lars@...afoo.de>
> Signed-off-by: Lars-Peter Clausen <lars@...afoo.de>
> Acked-by: Nicolas Ferre <nicolas.ferre@...rochip.com>
Whew, this sounds like it was a mess to hunt down. Glad the fix is simple!
Reviewed-by: Jacob Keller <jacob.e.keller@...el.com>
> ---
> drivers/net/ethernet/cadence/macb_main.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index f77bd1223c8f..541e4dda7950 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -1063,6 +1063,10 @@ static dma_addr_t macb_get_addr(struct macb *bp, struct macb_dma_desc *desc)
> }
> #endif
> addr |= MACB_BF(RX_WADDR, MACB_BFEXT(RX_WADDR, desc->addr));
> +#ifdef CONFIG_MACB_USE_HWSTAMP
> + if (bp->hw_dma_cap & HW_DMA_CAP_PTP)
> + addr &= ~GEM_BIT(DMA_RXVALID);
> +#endif
> return addr;
> }
>
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