* RE: (EXT) Re: [PATCH v2 1/1] edac: fsl_ddr_edac: fix expected data message
@ 2020-09-04 6:52 Gregor Herburger
2020-09-04 9:17 ` Borislav Petkov
0 siblings, 1 reply; 6+ messages in thread
From: Gregor Herburger @ 2020-09-04 6:52 UTC (permalink / raw)
To: Borislav Petkov
Cc: york.sun, mchehab, tony.luck, james.morse, rrichter, linux-edac,
linux-kernel
> > drivers/edac/fsl_ddr_edac.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/edac/fsl_ddr_edac.c b/drivers/edac/fsl_ddr_edac.c
> > index 6d8ea226010d..4b6989cf1947 100644
> > --- a/drivers/edac/fsl_ddr_edac.c
> > +++ b/drivers/edac/fsl_ddr_edac.c
> > @@ -343,9 +343,9 @@ static void fsl_mc_check(struct mem_ctl_info *mci)
> >
> > fsl_mc_printk(mci, KERN_ERR,
> > "Expected Data / ECC:\t%#8.8x_%08x / %#2.2x\n",
> > - cap_high ^ (1 << (bad_data_bit - 32)),
> > - cap_low ^ (1 << bad_data_bit),
> > - syndrome ^ (1 << bad_ecc_bit));
> > + (bad_data_bit > 31) ? cap_high ^ (1 << (bad_data_bit - 32)) : cap_high,
> > + (bad_data_bit <= 31) ? cap_low ^ (1 << (bad_data_bit)) : cap_low,
>
> But if bad_data_bit is -1, this check above will hit and you'd still
> shift by -1, IINM.
You are right. It worked on my machine, but i guess that is again machine-dependent.
> How about you fix it properly, clean it up and make it more readable in
> the process (pasting the code directly instead of a diff because a diff
> is less readable):
>
> if ((err_detect & DDR_EDE_SBE) && (bus_width == 64)) {
> sbe_ecc_decode(cap_high, cap_low, syndrome,
> &bad_data_bit, &bad_ecc_bit);
>
> if (bad_data_bit != -1) {
> if (bad_data_bit > 31)
> cap_high ^= 1 << (bad_data_bit - 32);
> else
> cap_low ^= 1 << bad_data_bit;
>
> fsl_mc_printk(mci, KERN_ERR, "Faulty Data bit: %d\n",
> bad_data_bit);
> fsl_mc_printk(mci, KERN_ERR, "Expected Data: %#8.8x_%08x\n",
> cap_high, cap_low);
> }
>
> if (bad_ecc_bit != -1) {
> fsl_mc_printk(mci, KERN_ERR, "Faulty ECC bit: %d\n",
> bad_ecc_bit);
> fsl_mc_printk(mci, KERN_ERR, "Expected ECC: %#2.2x\n",
> syndrome ^ (1 << bad_ecc_bit));
> }
> }
>
> This way you print only when the respective faulty bits have been
> properly found and not print anything otherwise.
The cap_low, cap_high and syndrome are used in the printk following the if-Block.
This will make expected data / captured data look the same.
>
> Hmm?
I would prefer printing exptected data and captured data in the same format, making it
easier to compare them directly.
diff --git a/drivers/edac/fsl_ddr_edac.c b/drivers/edac/fsl_ddr_edac.c
index 6d8ea226010d..880cf3f4712b 100644
--- a/drivers/edac/fsl_ddr_edac.c
+++ b/drivers/edac/fsl_ddr_edac.c
@@ -288,6 +288,9 @@ static void fsl_mc_check(struct mem_ctl_info *mci)
u32 cap_low;
int bad_data_bit;
int bad_ecc_bit;
+ u32 exp_high;
+ u32 exp_low;
+ u32 exp_syndrome;
err_detect = ddr_in32(pdata->mc_vbase + FSL_MC_ERR_DETECT);
if (!err_detect)
@@ -334,18 +337,32 @@ static void fsl_mc_check(struct mem_ctl_info *mci)
sbe_ecc_decode(cap_high, cap_low, syndrome,
&bad_data_bit, &bad_ecc_bit);
+ exp_high = cap_high;
+ exp_low = cap_low;
+ exp_syndrome = syndrome;
+
if (bad_data_bit != -1)
+ {
fsl_mc_printk(mci, KERN_ERR,
"Faulty Data bit: %d\n", bad_data_bit);
+
+ if (bad_data_bit < 32)
+ exp_low = cap_low ^ (1 << bad_data_bit);
+ else
+ exp_high = cap_high ^ (1 << (bad_data_bit - 32));
+ }
+
if (bad_ecc_bit != -1)
+ {
fsl_mc_printk(mci, KERN_ERR,
"Faulty ECC bit: %d\n", bad_ecc_bit);
+ exp_syndrome = syndrome ^ (1 << bad_ecc_bit);
+ }
+
fsl_mc_printk(mci, KERN_ERR,
"Expected Data / ECC:\t%#8.8x_%08x / %#2.2x\n",
- cap_high ^ (1 << (bad_data_bit - 32)),
- cap_low ^ (1 << bad_data_bit),
- syndrome ^ (1 << bad_ecc_bit));
+ exp_high, exp_low, exp_syndrome);
}
fsl_mc_printk(mci, KERN_ERR,
"Captured Data / ECC:\t%#8.8x_%08x / %#2.2x\n",
cap_high, cap_low, syndrome);
How about something like this?
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: (EXT) Re: [PATCH v2 1/1] edac: fsl_ddr_edac: fix expected data message
2020-09-04 6:52 (EXT) Re: [PATCH v2 1/1] edac: fsl_ddr_edac: fix expected data message Gregor Herburger
@ 2020-09-04 9:17 ` Borislav Petkov
2020-09-04 13:32 ` Gregor Herburger
0 siblings, 1 reply; 6+ messages in thread
From: Borislav Petkov @ 2020-09-04 9:17 UTC (permalink / raw)
To: Gregor Herburger
Cc: york.sun, mchehab, tony.luck, james.morse, rrichter, linux-edac,
linux-kernel
Your mail client broke threading...
On Fri, Sep 04, 2020 at 06:52:24AM +0000, Gregor Herburger wrote:
> The cap_low, cap_high and syndrome are used in the printk following the if-Block.
> This will make expected data / captured data look the same.
Right.
> @@ -334,18 +337,32 @@ static void fsl_mc_check(struct mem_ctl_info *mci)
> sbe_ecc_decode(cap_high, cap_low, syndrome,
> &bad_data_bit, &bad_ecc_bit);
>
> + exp_high = cap_high;
> + exp_low = cap_low;
> + exp_syndrome = syndrome;
> +
> if (bad_data_bit != -1)
> + {
Opening brace is on the same line for if-statements.
> fsl_mc_printk(mci, KERN_ERR,
> "Faulty Data bit: %d\n", bad_data_bit);
> +
> + if (bad_data_bit < 32)
> + exp_low = cap_low ^ (1 << bad_data_bit);
> + else
> + exp_high = cap_high ^ (1 << (bad_data_bit - 32));
> + }
> +
> if (bad_ecc_bit != -1)
> + {
Ditto.
> fsl_mc_printk(mci, KERN_ERR,
> "Faulty ECC bit: %d\n", bad_ecc_bit);
>
> + exp_syndrome = syndrome ^ (1 << bad_ecc_bit);
> + }
> +
> fsl_mc_printk(mci, KERN_ERR,
> "Expected Data / ECC:\t%#8.8x_%08x / %#2.2x\n",
> - cap_high ^ (1 << (bad_data_bit - 32)),
> - cap_low ^ (1 << bad_data_bit),
> - syndrome ^ (1 << bad_ecc_bit));
> + exp_high, exp_low, exp_syndrome);
> }
>
> fsl_mc_printk(mci, KERN_ERR,
> "Captured Data / ECC:\t%#8.8x_%08x / %#2.2x\n",
> cap_high, cap_low, syndrome);
>
> How about something like this?
My only concern here is that you'll be printing "Expected Data ..."
unconditionally even if either or both - bad_data_bit and bad_ecc_bit
- are -1.
If the driver cannot decode the data and/or ECC syndrome bits, then it
should say so - not dump expected data and claim that it is a valid
information.
So maybe in addition to the above:
if (bad_data_bit != -1) {
...
} else {
fsl_mc_printk(..., "Unable to decode the Faulty Data bit");
}
and the same for the ECC bit.
And then print only the expected data for the bit which sbe_ecc_decode()
found correctly and not say anything otherwise.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v2 1/1] edac: fsl_ddr_edac: fix expected data message
2020-09-04 9:17 ` Borislav Petkov
@ 2020-09-04 13:32 ` Gregor Herburger
2020-09-08 19:24 ` Borislav Petkov
0 siblings, 1 reply; 6+ messages in thread
From: Gregor Herburger @ 2020-09-04 13:32 UTC (permalink / raw)
To: Borislav Petkov
Cc: york.sun, mchehab, tony.luck, james.morse, rrichter, linux-edac,
linux-kernel, gregor.herburger
On Fri, Sep 04, 2020 at 11:17:18AM +0200, Borislav Petkov wrote:
> Your mail client broke threading...
>
Indeed. Guess I have to change the mail client. Sorry for that.
> On Fri, Sep 04, 2020 at 06:52:24AM +0000, Gregor Herburger wrote:
>
> > The cap_low, cap_high and syndrome are used in the printk following the if-Block.
> > This will make expected data / captured data look the same.
>
> Right.
>
> > @@ -334,18 +337,32 @@ static void fsl_mc_check(struct mem_ctl_info *mci)
> > sbe_ecc_decode(cap_high, cap_low, syndrome,
> > &bad_data_bit, &bad_ecc_bit);
> >
> > + exp_high = cap_high;
> > + exp_low = cap_low;
> > + exp_syndrome = syndrome;
> > +
> > if (bad_data_bit != -1)
> > + {
>
> Opening brace is on the same line for if-statements.
>
> > fsl_mc_printk(mci, KERN_ERR,
> > "Faulty Data bit: %d\n", bad_data_bit);
> > +
> > + if (bad_data_bit < 32)
> > + exp_low = cap_low ^ (1 << bad_data_bit);
> > + else
> > + exp_high = cap_high ^ (1 << (bad_data_bit - 32));
> > + }
> > +
> > if (bad_ecc_bit != -1)
> > + {
>
> Ditto.
>
> > fsl_mc_printk(mci, KERN_ERR,
> > "Faulty ECC bit: %d\n", bad_ecc_bit);
> >
> > + exp_syndrome = syndrome ^ (1 << bad_ecc_bit);
> > + }
> > +
> > fsl_mc_printk(mci, KERN_ERR,
> > "Expected Data / ECC:\t%#8.8x_%08x / %#2.2x\n",
> > - cap_high ^ (1 << (bad_data_bit - 32)),
> > - cap_low ^ (1 << bad_data_bit),
> > - syndrome ^ (1 << bad_ecc_bit));
> > + exp_high, exp_low, exp_syndrome);
> > }
> >
> > fsl_mc_printk(mci, KERN_ERR,
> > "Captured Data / ECC:\t%#8.8x_%08x / %#2.2x\n",
> > cap_high, cap_low, syndrome);
> >
> > How about something like this?
>
> My only concern here is that you'll be printing "Expected Data ..."
> unconditionally even if either or both - bad_data_bit and bad_ecc_bit
> - are -1.
That shouldn't happen. The whole if-block is only executed when a single
bit correctable error has occured (DDR_EDE_SBE). So we always should have
bad_data_bit or bad_ecc_bit (exclusively).
>
> If the driver cannot decode the data and/or ECC syndrome bits, then it
> should say so - not dump expected data and claim that it is a valid
> information.
>
Ok, that is reaonable. But that shouldn't that go into sbe_ecc_decode()?.
Currently sbe_ecc_decude() returns on the first error it finds. So we would
have to rework this function.
> So maybe in addition to the above:
>
> if (bad_data_bit != -1) {
> ...
> } else {
> fsl_mc_printk(..., "Unable to decode the Faulty Data bit");
> }
>
> and the same for the ECC bit.
>
I suggest adding such an message to sbe_ecc_decode(). Also to add an
return 0 on success and to check that before printing infos about single
bit errors.
> And then print only the expected data for the bit which sbe_ecc_decode()
> found correctly and not say anything otherwise.
>
Also i just noticed in the kernel log is no hint that this is an
single bit error. Maybe we should add this too?
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v2 1/1] edac: fsl_ddr_edac: fix expected data message
2020-09-04 13:32 ` Gregor Herburger
@ 2020-09-08 19:24 ` Borislav Petkov
2020-09-10 15:06 ` (EXT) " Gregor Herburger
0 siblings, 1 reply; 6+ messages in thread
From: Borislav Petkov @ 2020-09-08 19:24 UTC (permalink / raw)
To: Gregor Herburger
Cc: york.sun, mchehab, tony.luck, james.morse, rrichter, linux-edac,
linux-kernel
On Fri, Sep 04, 2020 at 03:32:58PM +0200, Gregor Herburger wrote:
> That shouldn't happen. The whole if-block is only executed when a single
> bit correctable error has occured (DDR_EDE_SBE). So we always should have
> bad_data_bit or bad_ecc_bit (exclusively).
Ooh, that sbe_ecc_decode() function would give you either the data bit
- if that one is in error - and if not the data bit, then the ECC bit.
Aha.
Ok, so what the driver should do, IMO, is this:
if (bad_data_bit != -1) {
...
fsl_mc_printk("Single-bit data error, ... ", bad_data_bit);
fsl_mc_printk("Expected Data/Captured Data, ... ", exp_high, exp_low, cap_high, cap_low);
}
if (bad_ecc_bit != -1) {
...
fsl_mc_printk("Single-bit ECC error, ... ", bad_ecc_bit);
fsl_mc_printk("Expected ECC/Captured ECC, ... ", exp_syndrome, syndrome);
}
This way you only print either the data or the ECC value which was in
error but not both.
Makes sense?
> Also i just noticed in the kernel log is no hint that this is an
> single bit error. Maybe we should add this too?
Yap, see above.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: (EXT) Re: [PATCH v2 1/1] edac: fsl_ddr_edac: fix expected data message
2020-09-08 19:24 ` Borislav Petkov
@ 2020-09-10 15:06 ` Gregor Herburger
2020-09-11 11:06 ` Borislav Petkov
0 siblings, 1 reply; 6+ messages in thread
From: Gregor Herburger @ 2020-09-10 15:06 UTC (permalink / raw)
To: Borislav Petkov
Cc: york.sun, mchehab, tony.luck, james.morse, rrichter, linux-edac,
linux-kernel, gregor.herburger
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: (EXT) Re: [PATCH v2 1/1] edac: fsl_ddr_edac: fix expected data message
2020-09-10 15:06 ` (EXT) " Gregor Herburger
@ 2020-09-11 11:06 ` Borislav Petkov
0 siblings, 0 replies; 6+ messages in thread
From: Borislav Petkov @ 2020-09-11 11:06 UTC (permalink / raw)
To: Gregor Herburger
Cc: york.sun, mchehab, tony.luck, james.morse, rrichter, linux-edac,
linux-kernel
On Thu, Sep 10, 2020 at 05:06:28PM +0200, Gregor Herburger wrote:
>
Dunno if you were trying to say something but this mail is empty:
Content-Length: 1
Lines: 1
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
^ permalink raw reply [flat|nested] 6+ messages in thread
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2020-09-04 6:52 (EXT) Re: [PATCH v2 1/1] edac: fsl_ddr_edac: fix expected data message Gregor Herburger
2020-09-04 9:17 ` Borislav Petkov
2020-09-04 13:32 ` Gregor Herburger
2020-09-08 19:24 ` Borislav Petkov
2020-09-10 15:06 ` (EXT) " Gregor Herburger
2020-09-11 11:06 ` Borislav Petkov
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