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SubjectRe: [PATCH] Revert "base: arch_topology: fix section mismatch build warnings"
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Hi Inami-san,

On 02/07/2018 09:32 AM, Gaku Inami wrote:
> This reverts commit 452562abb5b7 ("base: arch_topology: fix section
> mismatch build warnings"). It causes the notifier call hangs in some
> use-cases.
>
> In some cases with using maxcpus, some of cpus are booted first and
> then the remaining cpus are booted. As an example, some users who want
> to realize fast boot up often use the following procedure.
>
> 1) Define all CPUs on device tree (CA57x4 + CA53x4)
> 2) Add "maxcpus=4" in bootargs
> 3) Kernel boot up with CA57x4
> 4) After kernel boot up, CA53x4 is booted from user
>
> When kernel init was finished, CPUFREQ_POLICY_NOTIFIER was not still
> unregisterd. This means that "__init init_cpu_capacity_callback()"
> will be called after kernel init sequence. To avoid this problem,
> it needs to remove __init{,data} annotations by reverting this commit.
>
> Also, this commit was needed to fix kernel compile issue below.
> However, this issue was also fixed by another patch: commit 82d8ba717ccb
> ("arch_topology: Fix section miss match warning due to
> free_raw_capacity()") in v4.15 as well.
> Whereas commit 452562abb5b7 added all the missing __init annotations,
> commit 82d8ba717ccb removed it from free_raw_capacity().
>
> WARNING: vmlinux.o(.text+0x548f24): Section mismatch in reference
> from the function init_cpu_capacity_callback() to the variable
> .init.text:$x
> The function init_cpu_capacity_callback() references
> the variable __init $x.
> This is often because init_cpu_capacity_callback lacks a __init
> annotation or the annotation of $x is wrong.
>
> Signed-off-by: Gaku Inami <gaku.inami.xh@renesas.com>

Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>

This also helps with cpufreq driver module loading. W/o this revert I
get the following when trying to modprobe scpi-cpufreq on juno:

root@juno:/lib/modules# modprobe scpi-cpufreq
[ 171.994851] Unable to handle kernel paging request at virtual address
ffff000008f57708
[ 172.002708] Mem abort info:
[ 172.005471] ESR = 0x96000007
[ 172.008507] Exception class = DABT (current EL), IL = 32 bits
[ 172.014391] SET = 0, FnV = 0
[ 172.017410] EA = 0, S1PTW = 0
[ 172.020528] Data abort info:
[ 172.023384] ISV = 0, ISS = 0x00000007
[ 172.027190] CM = 0, WnR = 0
[ 172.030139] swapper pgtable: 4k pages, 48-bit VAs, pgd = 0000000015b245a1
[ 172.036867] [ffff000008f57708] *pgd=00000009ffffe003,
*pud=00000009ffffd003, *pmd=00000009ffffb003, *pte=0000000000000000
[ 172.047737] Internal error: Oops: 96000007 [#1] PREEMPT SMP
[ 172.053250] Modules linked in: scpi_cpufreq(+)
[ 172.057656] CPU: 1 PID: 2439 Comm: modprobe Not tainted
4.15.0-10759-ge237f98a9c13 #1
[ 172.065405] Hardware name: ARM Juno development board (r0) (DT)
[ 172.071265] pstate: a0000005 (NzCv daif -PAN -UAO)
[ 172.076012] pc : notifier_call_chain+0x34/0x90
[ 172.080411] lr : __blocking_notifier_call_chain+0x50/0x78
[ 172.085752] sp : ffff00000dc4b750
[ 172.089029] x29: ffff00000dc4b750 x28: ffff80097526b808
[ 172.094291] x27: 0000000000000040 x26: ffff0000090bbc30
[ 172.099551] x25: ffff00000913d000 x24: ffff00000913df98
[ 172.104811] x23: 0000000000000000 x22: ffff00000dc4b840
[ 172.110071] x21: ffff00000dc4b840 x20: 0000000000000000
[ 172.115330] x19: 00000000ffffffff x18: 0000000000000000
[ 172.120589] x17: 0000aaaaad4b02b0 x16: ffff00000814e9b8
[ 172.125848] x15: ffffffffffffffff x14: 0000000000000000
[ 172.131107] x13: ffff80097526b968 x12: ffff80097526b968
[ 172.136366] x11: 0000000000000000 x10: 0000000000000000
[ 172.141625] x9 : 0000000000000000 x8 : ffff8009753c1e00
[ 172.146884] x7 : 00000000000cf850 x6 : ffff000008f57708
[ 172.152143] x5 : 00000000ffffffff x4 : 0000000000000000
[ 172.157402] x3 : 00000000ffffffff x2 : ffff00000dc4b840
[ 172.162661] x1 : ffff000008f57708 x0 : ffff0000090bbcd8
[ 172.167922] Process modprobe (pid: 2439, stack limit =
0x000000005740a6c4)
[ 172.174724] Call trace:
[ 172.177143] notifier_call_chain+0x34/0x90
[ 172.181196] __blocking_notifier_call_chain+0x50/0x78
[ 172.186195] blocking_notifier_call_chain+0x14/0x20
[ 172.191025] cpufreq_set_policy+0x8c/0x1e0
[ 172.195077] cpufreq_init_policy+0x58/0x90
[ 172.199130] cpufreq_online+0x3d4/0x658
[ 172.202924] cpufreq_add_dev+0x78/0x88
[ 172.206635] subsys_interface_register+0x84/0xc8
[ 172.211203] cpufreq_register_driver+0x150/0x1d0
[ 172.215778] scpi_cpufreq_probe+0x28/0x80 [scpi_cpufreq]
[ 172.221036] platform_drv_probe+0x58/0xc0
[ 172.225003] driver_probe_device+0x224/0x308
[ 172.229227] __driver_attach+0xac/0xb0
[ 172.232935] bus_for_each_dev+0x54/0x98
[ 172.236729] driver_attach+0x20/0x28
[ 172.240265] bus_add_driver+0x108/0x228
[ 172.244060] driver_register+0x60/0xf8
[ 172.247769] __platform_driver_register+0x40/0x48
[ 172.252427] scpi_cpufreq_platdrv_init+0x18/0x1000 [scpi_cpufreq]
[ 172.258459] do_one_initcall+0x38/0x120
[ 172.262255] do_init_module+0x58/0x1b8
[ 172.265964] load_module+0x1ed8/0x21e8
[ 172.269672] SyS_finit_module+0xc0/0xd0
[ 172.273466] el0_svc_naked+0x20/0x24
[ 172.277004] Code: 54000320 2a0303f3 aa0203f6 aa0403f4 (f9400023)
[ 172.283035] ---[ end trace f70b068835918c13 ]---
Segmentation fault

[...]

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