RE: [PATCH v1] scsi: ufs: Use explicit access size in ufshcd_dump_regs

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> 
> On 09/01/2019 16:38, Jeffrey Hugo wrote:
> 
> >> On 11/12/2018 15:18, Marc Gonzalez wrote:
> >>
> >>> memcpy_fromio() doesn't provide any control over access size.
> >>> For example, on arm64, it is implemented using readb and readq.
> >>> This may trigger a synchronous external abort:
> >>>
> >>> [    3.729943] Internal error: synchronous external abort: 96000210 [#1]
> PREEMPT SMP
> >>> [    3.737000] Modules linked in:
> >>> [    3.744371] CPU: 2 PID: 1 Comm: swapper/0 Tainted: G S                4.20.0-
> rc4 #16
> >>> [    3.747413] Hardware name: Qualcomm Technologies, Inc. MSM8998 v1
> MTP (DT)
> >>> [    3.755295] pstate: 00000005 (nzcv daif -PAN -UAO)
> >>> [    3.761978] pc : __memcpy_fromio+0x68/0x80
> >>> [    3.766718] lr : ufshcd_dump_regs+0x50/0xb0
> >>> [    3.770767] sp : ffff00000807ba00
> >>> [    3.774830] x29: ffff00000807ba00 x28: 00000000fffffffb
> >>> [    3.778344] x27: ffff0000089db068 x26: ffff8000f6e58000
> >>> [    3.783728] x25: 000000000000000e x24: 0000000000000800
> >>> [    3.789023] x23: ffff8000f6e587c8 x22: 0000000000000800
> >>> [    3.794319] x21: ffff000008908368 x20: ffff8000f6e1ab80
> >>> [    3.799615] x19: 000000000000006c x18: ffffffffffffffff
> >>> [    3.804910] x17: 0000000000000000 x16: 0000000000000000
> >>> [    3.810206] x15: ffff000009199648 x14: ffff000089244187
> >>> [    3.815502] x13: ffff000009244195 x12: ffff0000091ab000
> >>> [    3.820797] x11: 0000000005f5e0ff x10: ffff0000091998a0
> >>> [    3.826093] x9 : 0000000000000000 x8 : ffff8000f6e1ac00
> >>> [    3.831389] x7 : 0000000000000000 x6 : 0000000000000068
> >>> [    3.836676] x5 : ffff8000f6e1abe8 x4 : 0000000000000000
> >>> [    3.841971] x3 : ffff00000928c868 x2 : ffff8000f6e1abec
> >>> [    3.847267] x1 : ffff00000928c868 x0 : ffff8000f6e1abe8
> >>> [    3.852567] Process swapper/0 (pid: 1, stack limit = 0x(____ptrval____))
> >>> [    3.857900] Call trace:
> >>> [    3.864473]  __memcpy_fromio+0x68/0x80
> >>> [    3.866683]  ufs_qcom_dump_dbg_regs+0x1c0/0x370
> >>> [    3.870522]  ufshcd_print_host_regs+0x168/0x190
> >>> [    3.874946]  ufshcd_init+0xd4c/0xde0
> >>> [    3.879459]  ufshcd_pltfrm_init+0x3c8/0x550
> >>> [    3.883264]  ufs_qcom_probe+0x24/0x60
> >>> [    3.887188]  platform_drv_probe+0x50/0xa0
> >>>
> >>> Assuming aligned 32-bit registers, let's use readl, after making
> >>> sure that 'offset' and 'len' are indeed multiples of 4.
> >>>
> >>> Fixes: ba80917d9932d ("scsi: ufs: ufshcd_dump_regs to use
> >>> memcpy_fromio")
> >>> Signed-off-by: Marc Gonzalez <marc.w.gonzalez@xxxxxxx>
> >>> ---
> >>>   drivers/scsi/ufs/ufshcd.c | 10 ++++++++--
> >>>   1 file changed, 8 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> >>> index 535180c01ce8..320bbd9849bc 100644
> >>> --- a/drivers/scsi/ufs/ufshcd.c
> >>> +++ b/drivers/scsi/ufs/ufshcd.c
> >>> @@ -112,13 +112,19 @@
> >>>   int ufshcd_dump_regs(struct ufs_hba *hba, size_t offset, size_t len,
> >>>   		     const char *prefix)
> >>>   {
> >>> -	u8 *regs;
> >>> +	u32 *regs;
> >>> +	size_t pos;
> >>> +
> >>> +	if (offset % 4 != 0 || len % 4 != 0) /* keep readl happy */
> >>> +		return -EINVAL;
> >
> > Hmm.  It seems like these cases could be handled, but I guess we
> > cannot necessarily assume that reading past the bounds specified by
> > the client is safe, so this seems reasonable.
> >
> >>>
> >>>   	regs = kzalloc(len, GFP_KERNEL);
> >>>   	if (!regs)
> >>>   		return -ENOMEM;
> >>>
> >>> -	memcpy_fromio(regs, hba->mmio_base + offset, len);
> >>> +	for (pos = 0; pos < len; pos += 4)
> >>> +		regs[pos / 4] = ufshcd_readl(hba, offset + pos);
> >>> +
> >>>   	ufshcd_hex_dump(prefix, regs, len);
> >>>   	kfree(regs);
> >>>
> >
> > Reviewed-by: Jeffrey Hugo <jhugo@xxxxxxxxxxxxxx>
> 
> James, Martin,
> 
> I haven't heard back from Vinayak. (In fact, his last review dates back to 2016.
> Should MAINTAINERS be updated? I can send a patch.)
> 
> Would you mind taking this patch through the SCSI tree?
> 
> Tomas, does "LGTM" translate to Acked-by? :-D
Yes, you can add my Ack.

Thanks
Tomas





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