parisc/mm: preallocate fixmap page tables at init

Christoph Biedl reported early OOM on recent kernels:

swapper: page allocation failure: order:0, mode:0x100(__GFP_ZERO),
nodemask=(null)
CPU: 0 PID: 0 Comm: swapper Not tainted 6.3.0-rc4+ #16
Hardware name: 9000/785/C3600
Backtrace:
[<10408594>] show_stack+0x48/0x5c
[<10e152d8>] dump_stack_lvl+0x48/0x64
[<10e15318>] dump_stack+0x24/0x34
[<105cf7f8>] warn_alloc+0x10c/0x1c8
[<105d068c>] __alloc_pages+0xbbc/0xcf8
[<105d0e4c>] __get_free_pages+0x28/0x78
[<105ad10c>] __pte_alloc_kernel+0x30/0x98
[<10406934>] set_fixmap+0xec/0xf4
[<10411ad4>] patch_map.constprop.0+0xa8/0xdc
[<10411bb0>] __patch_text_multiple+0xa8/0x208
[<10411d78>] patch_text+0x30/0x48
[<1041246c>] arch_jump_label_transform+0x90/0xcc
[<1056f734>] jump_label_update+0xd4/0x184
[<1056fc9c>] static_key_enable_cpuslocked+0xc0/0x110
[<1056fd08>] static_key_enable+0x1c/0x2c
[<1011362c>] init_mem_debugging_and_hardening+0xdc/0xf8
[<1010141c>] start_kernel+0x5f0/0xa98
[<10105da8>] start_parisc+0xb8/0xe4

Mem-Info:
active_anon:0 inactive_anon:0 isolated_anon:0
active_file:0 inactive_file:0 isolated_file:0
unevictable:0 dirty:0 writeback:0
slab_reclaimable:0 slab_unreclaimable:0
mapped:0 shmem:0 pagetables:0
sec_pagetables:0 bounce:0
kernel_misc_reclaimable:0
free:0 free_pcp:0 free_cma:0
Node 0 active_anon:0kB inactive_anon:0kB active_file:0kB
inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB
mapped:0kB dirty:0kB writeback:0kB shmem:0kB
+writeback_tmp:0kB kernel_stack:0kB pagetables:0kB sec_pagetables:0kB
all_unreclaimable? no
Normal free:0kB boost:0kB min:0kB low:0kB high:0kB
reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:0kB
inactive_file:0kB unevictable:0kB writepending:0kB
+present:1048576kB managed:1039360kB mlocked:0kB bounce:0kB free_pcp:0kB
local_pcp:0kB free_cma:0kB
lowmem_reserve[]: 0 0
Normal: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB
0*1024kB 0*2048kB 0*4096kB = 0kB
0 total pagecache pages
0 pages in swap cache
Free swap = 0kB
Total swap = 0kB
262144 pages RAM
0 pages HighMem/MovableOnly
2304 pages reserved
Backtrace:
[<10411d78>] patch_text+0x30/0x48
[<1041246c>] arch_jump_label_transform+0x90/0xcc
[<1056f734>] jump_label_update+0xd4/0x184
[<1056fc9c>] static_key_enable_cpuslocked+0xc0/0x110
[<1056fd08>] static_key_enable+0x1c/0x2c
[<1011362c>] init_mem_debugging_and_hardening+0xdc/0xf8
[<1010141c>] start_kernel+0x5f0/0xa98
[<10105da8>] start_parisc+0xb8/0xe4

Kernel Fault: Code=15 (Data TLB miss fault) at addr 0f7fe3c0
CPU: 0 PID: 0 Comm: swapper Not tainted 6.3.0-rc4+ #16
Hardware name: 9000/785/C3600

This happens because patching static key code temporarily maps it via
fixmap and if it happens before page allocator is initialized set_fixmap()
cannot allocate memory using pte_alloc_kernel().

Make sure that fixmap page tables are preallocated early so that
pte_offset_kernel() in set_fixmap() never resorts to pte allocation.

Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Helge Deller <deller@gmx.de>
Tested-by: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>
Tested-by: John David Anglin <dave.anglin@bell.net>
Cc: <stable@vger.kernel.org> # v6.4+

parisc: Fix set_fixmap() on PA1.x CPUs

Fix a kernel crash which happens on PA1.x CPUs while initializing the
FTRACE/KPROBE breakpoints. The PTE table entries for the fixmap area
were not created correctly.

Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: ccfbc68d41c2 ("parisc: add set_fixmap()/clear_fixmap()")
Cc: stable@vger.kernel.org # v5.2+

mm: pgtable: add shortcuts for accessing kernel PMD and PTE

The powerpc 32-bit implementation of pgtable has nice shortcuts for
accessing kernel PMD and PTE for a given virtual address. Make these
helpers available for all architectures.

[rppt@linux.ibm.com: microblaze: fix page table traversal in setup_rt_frame()]
Link: http://lkml.kernel.org/r/20200518191511.GD1118872@kernel.org
[akpm@linux-foundation.org: s/pmd_ptr_k/pmd_off_k/ in various powerpc places]

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/20200514170327.31389-9-rppt@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parisc: use pgtable-nopXd instead of 4level-fixup

parisc has two or three levels of page tables and can use appropriate
pgtable-nopXd and folding of the upper layers.

Replace usage of include/asm-generic/4level-fixup.h and explicit
definitions of __PAGETABLE_PxD_FOLDED in parisc with
include/asm-generic/pgtable-nopmd.h for two-level configurations and
with include/asm-generic/pgtable-nopud.h for three-lelve configurations
and adjust page table manipulation macros and functions accordingly.

Link: http://lkml.kernel.org/r/1572938135-31886-9-git-send-email-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Helge Deller <deller@gmx.de>
Cc: Anatoly Pugachev <matorola@gmail.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mark Salter <msalter@redhat.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Peter Rosin <peda@axentia.se>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rolf Eike Beer <eike-kernel@sf-tec.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parisc: add dynamic ftrace

This patch implements dynamic ftrace for PA-RISC. The required mcount
call sequences can get pretty long, so instead of patching the
whole call sequence out of the functions, we are using
-fpatchable-function-entry from gcc. This puts a configurable amount of
NOPS before/at the start of the function. Taking do_sys_open() as example,
which would look like this when the call is patched out:

1036b248: 08 00 02 40 nop
1036b24c: 08 00 02 40 nop
1036b250: 08 00 02 40 nop
1036b254: 08 00 02 40 nop

1036b258 <do_sys_open>:
1036b258: 08 00 02 40 nop
1036b25c: 08 03 02 41 copy r3,r1
1036b260: 6b c2 3f d9 stw rp,-14(sp)
1036b264: 08 1e 02 43 copy sp,r3
1036b268: 6f c1 01 00 stw,ma r1,80(sp)

When ftrace gets enabled for this function the kernel will patch these
NOPs to:

1036b248: 10 19 57 20 <address of ftrace>
1036b24c: 6f c1 00 80 stw,ma r1,40(sp)
1036b250: 48 21 3f d1 ldw -18(r1),r1
1036b254: e8 20 c0 02 bv,n r0(r1)

1036b258 <do_sys_open>:
1036b258: e8 3f 1f df b,l,n .-c,r1
1036b25c: 08 03 02 41 copy r3,r1
1036b260: 6b c2 3f d9 stw rp,-14(sp)
1036b264: 08 1e 02 43 copy sp,r3
1036b268: 6f c1 01 00 stw,ma r1,80(sp)

So the first NOP in do_sys_open() will be patched to jump backwards into
some minimal trampoline code which pushes a stackframe, saves r1 which
holds the return address, loads the address of the real ftrace function,
and branches to that location. For 64 Bit things are getting a bit more
complicated (and longer) because we must make sure that the address of
ftrace location is 8 byte aligned, and the offset passed to ldd for
fetching the address is 8 byte aligned as well.

Note that gcc has a bug which misplaces the function label, and needs a
patch to make dynamic ftrace work. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90751 for details.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Helge Deller <deller@gmx.de>

parisc: add WARN_ON() to clear_fixmap

Calling clear_fixmap() on an already cleared fixed mapping is
a bad thing to do. Add a WARN_ON() to catch such issues.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Helge Deller <deller@gmx.de>

parisc: add set_fixmap()/clear_fixmap()

These functions will be used for adding code patching
functions later.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Helge Deller <deller@gmx.de>