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Date: Sat, 17 Jul 2021 17:57:50 +0200 From: Christophe Leroy <christophe.leroy@...roup.eu> To: Guenter Roeck <linux@...ck-us.net> Cc: linuxppc-dev@...ts.ozlabs.org, Paul Mackerras <paulus@...ba.org>, Oliver O'Halloran <oohall@...il.com>, Geert Uytterhoeven <geert@...ux-m68k.org>, linux-kernel@...r.kernel.org, Michael Ellerman <mpe@...erman.id.au> Subject: Re: [PATCH] powerpc/chrp: Revert "Move PHB discovery" and "Make hydra_init() static" Guenter Roeck <linux@...ck-us.net> a écrit : > This patch reverts commit 407d418f2fd4 ("powerpc/chrp: Move PHB > discovery") and commit 9634afa67bfd ("powerpc/chrp: Make hydra_init() > static"). > > Running the upstream kernel on Qemu's brand new "pegasos2" emulation > results in a variety of backtraces such as > > Kernel attempted to write user page (a1) - exploit attempt? (uid: 0) > ------------[ cut here ]------------ > Bug: Write fault blocked by KUAP! > WARNING: CPU: 0 PID: 0 at arch/powerpc/mm/fault.c:230 > do_page_fault+0x4f4/0x920 > CPU: 0 PID: 0 Comm: swapper Not tainted 5.13.2 #40 > NIP: c0021824 LR: c0021824 CTR: 00000000 > REGS: c1085d50 TRAP: 0700 Not tainted (5.13.2) > MSR: 00021032 <ME,IR,DR,RI> CR: 24042254 XER: 00000000 > > GPR00: c0021824 c1085e10 c0f8c520 00000021 3fffefff c1085c60 > c1085c58 00000000 > GPR08: 00001032 00000000 00000000 c0ffb3ec 44042254 00000000 > 00000000 00000004 > GPR16: 00000000 ffffffff 000000c4 000000d0 0188c6e0 01006000 > 00000001 40b14000 > GPR24: c0ec000c 00000300 02000000 00000000 42000000 000000a1 > 00000000 c1085e60 > NIP [c0021824] do_page_fault+0x4f4/0x920 > LR [c0021824] do_page_fault+0x4f4/0x920 > Call Trace: > [c1085e10] [c0021824] do_page_fault+0x4f4/0x920 (unreliable) > [c1085e50] [c0004254] DataAccess_virt+0xd4/0xe4 > > and the system fails to boot. Bisect points to commit 407d418f2fd4 > ("powerpc/chrp: Move PHB discovery"). Reverting this patch together with > commit 9634afa67bfd ("powerpc/chrp: Make hydra_init() static") fixes > the problem. Isn't there more than that in the backtrace ? If there is a fault blocked by Kuap, it means there is a fault. It should be visible in the traces. Should we fix the problem instead of reverting the commit that made the problem visible ? > > Cc: Oliver O'Halloran <oohall@...il.com> > Cc: Geert Uytterhoeven <geert@...ux-m68k.org> > Fixes: 407d418f2fd4 ("powerpc/chrp: Move PHB discovery") > Signed-off-by: Guenter Roeck <linux@...ck-us.net> > --- > arch/powerpc/include/asm/hydra.h | 2 ++ > arch/powerpc/platforms/chrp/pci.c | 11 ++--------- > arch/powerpc/platforms/chrp/setup.c | 12 +++++++++++- > 3 files changed, 15 insertions(+), 10 deletions(-) > > diff --git a/arch/powerpc/include/asm/hydra.h > b/arch/powerpc/include/asm/hydra.h > index d024447283a0..ae02eb53d6ef 100644 > --- a/arch/powerpc/include/asm/hydra.h > +++ b/arch/powerpc/include/asm/hydra.h > @@ -94,6 +94,8 @@ extern volatile struct Hydra __iomem *Hydra; > #define HYDRA_INT_EXT7 18 /* Power Off Request */ > #define HYDRA_INT_SPARE 19 > > +extern int hydra_init(void); > + > #endif /* __KERNEL__ */ > > #endif /* _ASMPPC_HYDRA_H */ > diff --git a/arch/powerpc/platforms/chrp/pci.c > b/arch/powerpc/platforms/chrp/pci.c > index 76e6256cb0a7..b2c2bf35b76c 100644 > --- a/arch/powerpc/platforms/chrp/pci.c > +++ b/arch/powerpc/platforms/chrp/pci.c > @@ -131,7 +131,8 @@ static struct pci_ops rtas_pci_ops = > > volatile struct Hydra __iomem *Hydra = NULL; > > -static int __init hydra_init(void) > +int __init > +hydra_init(void) > { > struct device_node *np; > struct resource r; > @@ -313,14 +314,6 @@ chrp_find_bridges(void) > } > } > of_node_put(root); > - > - /* > - * "Temporary" fixes for PCI devices. > - * -- Geert > - */ > - hydra_init(); /* Mac I/O */ > - > - pci_create_OF_bus_map(); > } > > /* SL82C105 IDE Control/Status Register */ > diff --git a/arch/powerpc/platforms/chrp/setup.c > b/arch/powerpc/platforms/chrp/setup.c > index 3cfc382841e5..c45435aa5e36 100644 > --- a/arch/powerpc/platforms/chrp/setup.c > +++ b/arch/powerpc/platforms/chrp/setup.c > @@ -334,11 +334,22 @@ static void __init chrp_setup_arch(void) > /* On pegasos, enable the L2 cache if not already done by OF */ > pegasos_set_l2cr(); > > + /* Lookup PCI host bridges */ > + chrp_find_bridges(); > + > + /* > + * Temporary fixes for PCI devices. > + * -- Geert > + */ > + hydra_init(); /* Mac I/O */ > + > /* > * Fix the Super I/O configuration > */ > sio_init(); > > + pci_create_OF_bus_map(); > + > /* > * Print the banner, then scroll down so boot progress > * can be printed. -- Cort > @@ -571,7 +582,6 @@ define_machine(chrp) { > .name = "CHRP", > .probe = chrp_probe, > .setup_arch = chrp_setup_arch, > - .discover_phbs = chrp_find_bridges, > .init = chrp_init2, > .show_cpuinfo = chrp_show_cpuinfo, > .init_IRQ = chrp_init_IRQ, > -- > 2.25.1
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