mm: ptdump: have ptdump_check_wx() return bool

Have ptdump_check_wx() return true when the check is successful or false
otherwise.

[akpm@linux-foundation.org: fix a couple of build issues (x86_64 allmodconfig)]
Link: https://lkml.kernel.org/r/7943149fe955458cb7b57cd483bf41a3aad94684.1706610398.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Greg KH <greg@kroah.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Phong Tran <tranmanphong@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Steven Price <steven.price@arm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arm64, powerpc, riscv, s390, x86: ptdump: refactor CONFIG_DEBUG_WX

All architectures using the core ptdump functionality also implement
CONFIG_DEBUG_WX, and they all do it more or less the same way, with a
function called debug_checkwx() that is called by mark_rodata_ro(), which
is a substitute to ptdump_check_wx() when CONFIG_DEBUG_WX is set and a
no-op otherwise.

Refactor by centrally defining debug_checkwx() in linux/ptdump.h and call
debug_checkwx() immediately after calling mark_rodata_ro() instead of
calling it at the end of every mark_rodata_ro().

On x86_32, mark_rodata_ro() first checks __supported_pte_mask has _PAGE_NX
before calling debug_checkwx(). Now the check is inside the callee
ptdump_walk_pgd_level_checkwx().

On powerpc_64, mark_rodata_ro() bails out early before calling
ptdump_check_wx() when the MMU doesn't have KERNEL_RO feature. The check
is now also done in ptdump_check_wx() as it is called outside
mark_rodata_ro().

Link: https://lkml.kernel.org/r/a59b102d7964261d31ead0316a9f18628e4e7a8e.1706610398.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Greg KH <greg@kroah.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Phong Tran <tranmanphong@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Steven Price <steven.price@arm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: ptdump: expand type of 'val' in note_page()

The page table entry is passed in the 'val' argument to note_page(),
however this was previously an "unsigned long" which is fine on 64-bit
platforms. But for 32 bit x86 it is not always big enough to contain a
page table entry which may be 64 bits.

Change the type to u64 to ensure that it is always big enough.

[akpm@linux-foundation.org: fix riscv]
Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200521152308.33096-3-steven.price@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

x86: mm: ptdump: calculate effective permissions correctly

Patch series "Fix W+X debug feature on x86"

Jan alerted me[1] that the W+X detection debug feature was broken in x86
by my change[2] to switch x86 to use the generic ptdump infrastructure.

Fundamentally the approach of trying to move the calculation of
effective permissions into note_page() was broken because note_page() is
only called for 'leaf' entries and the effective permissions are passed
down via the internal nodes of the page tree. The solution I've taken
here is to create a new (optional) callback which is called for all
nodes of the page tree and therefore can calculate the effective
permissions.

Secondly on some configurations (32 bit with PAE) "unsigned long" is not
large enough to store the table entries. The fix here is simple - let's
just use a u64.

[1] https://lore.kernel.org/lkml/d573dc7e-e742-84de-473d-f971142fa319@suse.com/
[2] 2ae27137b2db ("x86: mm: convert dump_pagetables to use walk_page_range")

This patch (of 2):

By switching the x86 page table dump code to use the generic code the
effective permissions are no longer calculated correctly because the
note_page() function is only called for *leaf* entries. To calculate
the actual effective permissions it is necessary to observe the full
hierarchy of the page tree.

Introduce a new callback for ptdump which is called for every entry and
can therefore update the prot_levels array correctly. note_page() can
then simply access the appropriate element in the array.

[steven.price@arm.com: make the assignment conditional on val != 0]
Link: http://lkml.kernel.org/r/430c8ab4-e7cd-6933-dde6-087fac6db872@arm.com
Fixes: 2ae27137b2db ("x86: mm: convert dump_pagetables to use walk_page_range")
Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200521152308.33096-1-steven.price@arm.com
Link: http://lkml.kernel.org/r/20200521152308.33096-2-steven.price@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

x86: mm: avoid allocating struct mm_struct on the stack

struct mm_struct is quite large (~1664 bytes) and so allocating on the
stack may cause problems as the kernel stack size is small.

Since ptdump_walk_pgd_level_core() was only allocating the structure so
that it could modify the pgd argument we can instead introduce a pgd
override in struct mm_walk and pass this down the call stack to where it
is needed.

Since the correct mm_struct is now being passed down, it is now also
unnecessary to take the mmap_sem semaphore because ptdump_walk_pgd() will
now take the semaphore on the real mm.

[steven.price@arm.com: restore missed arm64 changes]
Link: http://lkml.kernel.org/r/20200108145710.34314-1-steven.price@arm.com
Link: http://lkml.kernel.org/r/20200108145710.34314-1-steven.price@arm.com
Signed-off-by: Steven Price <steven.price@arm.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zong Li <zong.li@sifive.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: ptdump: reduce level numbers by 1 in note_page()

Rather than having to increment the 'depth' number by 1 in ptdump_hole(),
let's change the meaning of 'level' in note_page() since that makes the
code simplier.

Note that for x86, the level numbers were previously increased by 1 in
commit 45dcd2091363 ("x86/mm/dump_pagetables: Fix printout of p4d level")
and the comment "Bit 7 has a different meaning" was not updated, so this
change also makes the code match the comment again.

Link: http://lkml.kernel.org/r/20191218162402.45610-24-steven.price@arm.com
Signed-off-by: Steven Price <steven.price@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zong Li <zong.li@sifive.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: add generic ptdump

Add a generic version of page table dumping that architectures can opt-in
to.

Link: http://lkml.kernel.org/r/20191218162402.45610-20-steven.price@arm.com
Signed-off-by: Steven Price <steven.price@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zong Li <zong.li@sifive.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>