Messages in this thread | | | Subject | Re: [PATCH v7 2/2] ARM: ftrace: Add MODULE_PLTS support | From | Florian Fainelli <> | Date | Wed, 10 Mar 2021 08:14:07 -0800 |
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On 3/9/2021 11:23 PM, Alexander Sverdlin wrote: > Hi! > > On 09/03/2021 18:42, Qais Yousef wrote: >>>> I tried on 5.12-rc2 and 5.11 but couldn't reproduce the problem using your >> I still can't reproduce on 5.12-rc2. >> >> I do have CONFIG_ARM_MODULE_PLTS=y. Do you need to do something else after >> loading the module? I tried starting ftrace, but maybe there's a particular >> combination required? > > You need to load a BIG module, so big that it has no place in the modules area > any more and goes to vmalloc area.
You absolutely need a very big module maybe more than one. When I tested this, I could use the two proprietary modules (*sigh*) that I needed to exercise against and loading one but not the other was not enough to make the second module loading spill into vmalloc space.
> >>>> instructions on the other email. But most likely because I'm hitting another >>>> problem that could be masking it. I'm not sure it is related or just randomly >>>> happened to hit it. >>>> >>>> Did you see something similar? >>> [...] >>> >>>> [ 0.000000] [<c1b01a38>] (ftrace_bug) from [<c046316c>] (ftrace_process_locs+0x2b0/0x518) >>>> [ 0.000000] r7:c3817ac4 r6:c38040c0 r5:00000a3c r4:000134e4 >>>> [ 0.000000] [<c0462ebc>] (ftrace_process_locs) from [<c2b25240>] (ftrace_init+0xc8/0x174) >>>> [ 0.000000] r10:c2ffa000 r9:c2be8a78 r8:c2c5d1fc r7:c2c0c208 r6:00000001 r5:c2d0908c >>>> [ 0.000000] r4:c362f518 >>>> [ 0.000000] [<c2b25178>] (ftrace_init) from [<c2b00e14>] (start_kernel+0x2f4/0x5b8) >>>> [ 0.000000] r9:c2be8a78 r8:dbfffec0 r7:00000000 r6:c36385cc r5:c2d08f00 r4:c2ffa000 >>>> [ 0.000000] [<c2b00b20>] (start_kernel) from [<00000000>] (0x0) >>> This means, FTRACE has more problems with your kernel/compiler/platform, I've addressed similar issue >>> in the past, but my patch should be long merged: >>> >>> https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1817963.html >>> >>> Could it be the same problem as here: >>> https://www.spinics.net/lists/arm-kernel/msg854022.html >>> >>> Seems that the size check deserves something line BUILD_BUG_ON() with FTRACE... >> So I only see this when I convert all modules to be built-in >> >> sed -i 's/=m/=y/' .config >> >> FWIW, I see the problem with your patch applied too. Trying to dig more into >> it.. > > Then it's definitely the problem explained in the second link. If you have THUMB2 kernel, maybe > you have to switch to ARM. >
-- Florian
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