On Mon, 14 Aug 2023 09:40:44 +0000 Christophe Leroy <christophe.le...@csgroup.eu> wrote:
> Interesting. That means we get stuck somewhere around MMU_init()
>
> We know that MMU_init_hw() is called and runs at least until:
>
> pr_info("Total memory = %lldMB; using %ldkB for hash table\n",
> (unsigned long long)(total_memory >> 20), Hash_size >> 10);
>
> But we never reach the print in setup_kuap() which is itself called by
> set_kup():
> pr_info("Activating Kernel Userspace Access Protection\n");
>
>
> Could you try to narrow more the issue by spreading pr_info() at places
> in the code below and/or the called functions ? Either we never come
> back from MMU_init_hw(), or one of mapin_ram() btext_unmap()
> kasan_mmu_init() fails.
>
> So the piece of code we are interested in is located in
> arch/powerpc/mm/init_32.c and is:
>
> /* Initialize the MMU hardware */
> if (ppc_md.progress)
> ppc_md.progress("MMU:hw init", 0x300);
> ==> MMU_init_hw();
>
> /* Map in all of RAM starting at KERNELBASE */
> if (ppc_md.progress)
> ppc_md.progress("MMU:mapin", 0x301);
> mapin_ram();
>
> /* Initialize early top-down ioremap allocator */
> ioremap_bot = IOREMAP_TOP;
>
> if (ppc_md.progress)
> ppc_md.progress("MMU:exit", 0x211);
>
> /* From now on, btext is no longer BAT mapped if it was at all */
> #ifdef CONFIG_BOOTX_TEXT
> btext_unmap();
> #endif
>
> kasan_mmu_init();
>
> ==> setup_kup();
I added a pr_info(); right after MMU_init_hw(); and another one right after
setup_kup();.
Output of PPC_EARLY_DEBUG changes so that I get an additional black blank line
after
[ 0.000000] printk: bootconsole [udbg0] enabled
[ 0.000000] Total memory = 2048MB; using 4096kB for hash table
and the freeze afterwards. So it looks like we return from MMU_init_hw() but
not from setup_kup().
The dmesg of a warm boot (after first booting with kernel 6.4.10) supports that
as it also shows the 1st blank line and the 2nd one just after activating
KUEP/KUAP:
[ 0.000000] printk: bootconsole [udbg0] enabled
[ 0.000000] Total memory = 2048MB; using 4096kB for hash table
[ 0.000000]
[ 0.000000] Activating Kernel Userspace Access Protection
[ 0.000000] Activating Kernel Userspace Execution Prevention
[ 0.000000]
[ 0.000000] Linux version 6.5.0-rc6-PMacG4-dirty (root@T1000) (gcc (Gentoo
12.3.1_p20230526 p2) 12.3.1 20230526, GNU ld (Gentoo 2.40 p7) 2.40.0) #1 SMP
Mon Aug 14 18:05:17 CEST 2023
As the 2nd blank line from pr_info() is just after KUAP, KUEP initialization I
thought these might be a problem. But if I deactivate KUAP/KUAP in the kernel
.config I still get the freeze sot it must be something else.
Regards,
Erhard
dmesg_65-rc6_g4-
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