powerpc/ftrace: Ignore ftrace locations in exit text sections

Michael reported that we are seeing an ftrace bug on bootup when KASAN
is enabled and we are using -fpatchable-function-entry:

ftrace

powerpc/ftrace: Ignore ftrace locations in exit text sections

Michael reported that we are seeing an ftrace bug on bootup when KASAN
is enabled and we are using -fpatchable-function-entry:

ftrace: allocating 47780 entries in 18 pages
ftrace-powerpc: 0xc0000000020b3d5c: No module provided for non-kernel address
------------[ ftrace bug ]------------
ftrace faulted on modifying
[<c0000000020b3d5c>] 0xc0000000020b3d5c
Initializing ftrace call sites
ftrace record flags: 0
(0)
expected tramp: c00000000008cef4
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:2180 ftrace_bug+0x3c0/0x424
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 6.5.0-rc3-00120-g0f71dcfb4aef #860
Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries
NIP: c0000000003aa81c LR: c0000000003aa818 CTR: 0000000000000000
REGS: c0000000033cfab0 TRAP: 0700 Not tainted (6.5.0-rc3-00120-g0f71dcfb4aef)
MSR: 8000000002021033 <SF,VEC,ME,IR,DR,RI,LE> CR: 28028240 XER: 00000000
CFAR: c0000000002781a8 IRQMASK: 3
...
NIP [c0000000003aa81c] ftrace_bug+0x3c0/0x424
LR [c0000000003aa818] ftrace_bug+0x3bc/0x424
Call Trace:
ftrace_bug+0x3bc/0x424 (unreliable)
ftrace_process_locs+0x5f4/0x8a0
ftrace_init+0xc0/0x1d0
start_kernel+0x1d8/0x484

With CONFIG_FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY=y and
CONFIG_KASAN=y, compiler emits nops in functions that it generates for
registering and unregistering global variables (unlike with -pg and
-mprofile-kernel where calls to _mcount() are not generated in those
functions). Those functions then end up in INIT_TEXT and EXIT_TEXT
respectively. We don't expect to see any profiled functions in
EXIT_TEXT, so ftrace_init_nop() assumes that all addresses that aren't
in the core kernel text belongs to a module. Since these functions do
not match that criteria, we see the above bug.

Address this by having ftrace ignore all locations in the text exit
sections of vmlinux.

Fixes: 0f71dcfb4aef ("powerpc/ftrace: Add support for -fpatchable-function-entry")
Cc: [email protected] # v6.6+
Reported-by: Michael Ellerman <[email protected]>
Signed-off-by: Naveen N Rao <[email protected]>
Reviewed-by: Benjamin Gray <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://msgid.link/[email protected]

show more ...

powerpc/ftrace: Extend ftrace support for large kernels to ppc32

Commit 67361cf8071286 ("powerpc/ftrace: Handle large kernel configs")
added ftrace support for ppc64 kernel images with a text sectio

powerpc/ftrace: Extend ftrace support for large kernels to ppc32

Commit 67361cf8071286 ("powerpc/ftrace: Handle large kernel configs")
added ftrace support for ppc64 kernel images with a text section larger
than 32MB. The approach itself isn't specific to ppc64, so extend the
same to also work on ppc32.

While at it, reduce the space reserved for the stub from 64 bytes to 32
bytes since the different stub variants are all less than 8
instructions.

To reduce use of #ifdef, a stub implementation is provided for
kernel_toc_address() and -SZ_2G is cast to 'long long' to prevent
errors on ppc32.

Signed-off-by: Naveen N Rao <[email protected]>
Reviewed-by: Christophe Leroy <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://msgid.link/9fa3258cbb9105cf8a0a8135214d44ffbc75fe84.1687166935.git.naveen@kernel.org

show more ...

powerpc/64: vmlinux support building with PCREL addresing

PC-Relative or PCREL addressing is an extension to the ELF ABI which
uses Power ISA v3.1 PC-relative instructions to calculate addresses,
ra

powerpc/64: vmlinux support building with PCREL addresing

PC-Relative or PCREL addressing is an extension to the ELF ABI which
uses Power ISA v3.1 PC-relative instructions to calculate addresses,
rather than the traditional TOC scheme.

Add an option to build vmlinux using pcrel addressing. Modules continue
to use TOC addressing.

- TOC address helpers and r2 are poisoned with -1 when running vmlinux.
r2 could be used for something useful once things are ironed out.

- Assembly must call C functions with @notoc annotation, or the linker
complains aobut a missing nop after the call. This is done with the
CFUNC macro introduced earlier.

- Boot: with the exception of prom_init, the execution branches to the
kernel virtual address early in boot, before any addresses are
generated, which ensures 34-bit pcrel addressing does not miss the
high PAGE_OFFSET bits. TOC relative addressing has a similar
requirement. prom_init does not go to the virtual address and its
addresses should not carry over to the post-prom kernel.

- Ftrace trampolines are converted from TOC addressing to pcrel
addressing, including module ftrace trampolines that currently use the
kernel TOC to find ftrace target functions.

- BPF function prologue and function calling generation are converted
from TOC to pcrel.

- copypage_64.S has an interesting problem, prefixed instructions have
alignment restrictions so the linker can add padding, which makes the
assembler treat the difference between two local labels as
non-constant even if alignment is arranged so padding is not required.
This may need toolchain help to solve nicely, for now move the prefix
instruction out of the alternate patch section to work around it.

This reduces kernel text size by about 6%.

Signed-off-by: Nicholas Piggin <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://msgid.link/[email protected]

show more ...

powerpc/vmlinux.lds: Add an explicit symbol for the SRWX boundary

Currently __init_begin is used as the boundary for strict RWX between
executable/read-only text and data, and non-executable (after

powerpc/vmlinux.lds: Add an explicit symbol for the SRWX boundary

Currently __init_begin is used as the boundary for strict RWX between
executable/read-only text and data, and non-executable (after boot) code
and data.

But that's a little subtle, so add an explicit symbol to document that
the SRWX boundary lies there, and add a comment making it clear that
__init_begin must also begin there.

Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...

powerpc/64: Remove unused prom_init_toc symbols

Commit 24d33ac5b8ff ("powerpc/64s: Make prom_init require RELOCATABLE")
made prom_init depend on CONFIG_RELOCATABLE.

But it missed cleaning up a case

powerpc/64: Remove unused prom_init_toc symbols

Commit 24d33ac5b8ff ("powerpc/64s: Make prom_init require RELOCATABLE")
made prom_init depend on CONFIG_RELOCATABLE.

But it missed cleaning up a case in the linker script for RELOCATABLE=n,
and associated symbols. Remove them now.

Fixes: 24d33ac5b8ff ("powerpc/64s: Make prom_init require RELOCATABLE")
Reported-by: Christophe Leroy <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...

powerpc: Move patch sites out of asm-prototypes.h

The definitions for the patch sites etc. don't belong in
asm-prototypes.h, they are not EXPORT'ed asm symbols.

Move them into sections.h which is t

powerpc: Move patch sites out of asm-prototypes.h

The definitions for the patch sites etc. don't belong in
asm-prototypes.h, they are not EXPORT'ed asm symbols.

Move them into sections.h which is traditionally used for asm symbols.

Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...

asm-generic: Refactor dereference_[kernel]_function_descriptor()

dereference_function_descriptor() and
dereference_kernel_function_descriptor() are identical on the
three architectures implementing

asm-generic: Refactor dereference_[kernel]_function_descriptor()

dereference_function_descriptor() and
dereference_kernel_function_descriptor() are identical on the
three architectures implementing them.

Make them common and put them out-of-line in kernel/extable.c
which is one of the users and has similar type of functions.

Signed-off-by: Christophe Leroy <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Arnd Bergmann <[email protected]>
Acked-by: Helge Deller <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/449db09b2eba57f4ab05f80102a67d8675bc8bcd.1644928018.git.christophe.leroy@csgroup.eu

show more ...

asm-generic: Define 'func_desc_t' to commonly describe function descriptors

We have three architectures using function descriptors, each with its
own type and name.

Add a common typedef that can be

asm-generic: Define 'func_desc_t' to commonly describe function descriptors

We have three architectures using function descriptors, each with its
own type and name.

Add a common typedef that can be used in generic code.

Also add a stub typedef for architecture without function descriptors,
to avoid a forest of #ifdefs.

It replaces the similar 'func_desc_t' previously defined in
arch/powerpc/kernel/module_64.c

Signed-off-by: Christophe Leroy <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Acked-by: Helge Deller <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/f1f91b142b3c1082bdc1586ce71c9bac1e75213c.1644928018.git.christophe.leroy@csgroup.eu

show more ...

asm-generic: Define CONFIG_HAVE_FUNCTION_DESCRIPTORS

Replace HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR by a config option
named CONFIG_HAVE_FUNCTION_DESCRIPTORS and use it instead of
'dereference_functio

asm-generic: Define CONFIG_HAVE_FUNCTION_DESCRIPTORS

Replace HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR by a config option
named CONFIG_HAVE_FUNCTION_DESCRIPTORS and use it instead of
'dereference_function_descriptor' macro to know whether an
arch has function descriptors.

To limit churn in one of the following patches, use
an #ifdef/#else construct with empty first part
instead of an #ifndef in asm-generic/sections.h

On powerpc, make sure the config option matches the ABI used
by the compiler with a BUILD_BUG_ON() and add missing _CALL_ELF=2
when calling 'sparse' so that sparse sees the same piece of
code as GCC.

And include a helper to check whether an arch has function
descriptors or not : have_function_descriptors()

Signed-off-by: Christophe Leroy <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Nicholas Piggin <[email protected]>
Acked-by: Helge Deller <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/4a0f11fb0ea74a3197bc44dd7ba25e53a24fd03d.1644928018.git.christophe.leroy@csgroup.eu

show more ...

powerpc: Use 'struct func_desc' instead of 'struct ppc64_opd_entry'

'struct ppc64_opd_entry' is somehow redundant with 'struct func_desc',
the later is more correct/complete as it includes the third

powerpc: Use 'struct func_desc' instead of 'struct ppc64_opd_entry'

'struct ppc64_opd_entry' is somehow redundant with 'struct func_desc',
the later is more correct/complete as it includes the third
field which is unused.

So use 'struct func_desc' instead of 'struct ppc64_opd_entry'

Signed-off-by: Christophe Leroy <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Daniel Axtens <[email protected]>
Reviewed-by: Nicholas Piggin <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/34e76bac6cbe95a63ecd37df69fb7feb93b0ea7c.1644928018.git.christophe.leroy@csgroup.eu

show more ...

powerpc/toc: Future proof kernel toc

This patch future-proofs the kernel against linker changes that might
put the toc pointer at some location other than .got+0x8000, by
replacing __toc_start+0x800

powerpc/toc: Future proof kernel toc

This patch future-proofs the kernel against linker changes that might
put the toc pointer at some location other than .got+0x8000, by
replacing __toc_start+0x8000 with .TOC. throughout. If the kernel's
idea of the toc pointer doesn't agree with the linker, bad things
happen.

prom_init.c code relocating its toc is also changed so that a symbolic
__prom_init_toc_start toc-pointer relative address is calculated
rather than assuming that it is always at toc-pointer - 0x8000. The
length calculations loading values from the toc are also avoided.
It's a little incestuous to do that with unreloc_toc picking up
adjusted values (which is fine in practice, they both adjust by the
same amount if all goes well).

I've also changed the way .got is aligned in vmlinux.lds and
zImage.lds, mostly so that dumping out section info by objdump or
readelf plainly shows the alignment is 256. This linker script
feature was added 2005-09-27, available in FSF binutils releases from
2.17 onwards. Should be safe to use in the kernel, I think.

Finally, put *(.got) before the prom_init.o entry which only needs
*(.toc), so that the GOT header goes in the correct place. I don't
believe this makes any difference for the kernel as it would for
dynamic objects being loaded by ld.so. That change is just to stop
lusers who blindly copy kernel scripts being led astray. Of course,
this change needs the prom_init.c changes.

Some notes on .toc and .got.

.toc is a compiler generated section of addresses. .got is a linker
generated section of addresses, generally built when the linker sees
R_*_*GOT* relocations. In the case of powerpc64 ld.bfd, there are
multiple generated .got sections, one per input object file. So you
can somewhat reasonably write in a linker script an input section
statement like *prom_init.o(.got .toc) to mean "the .got and .toc
section for files matching *prom_init.o". On other architectures that
doesn't make sense, because the linker generally has just one .got
section. Even on powerpc64, note well that the GOT entries for
prom_init.o may be merged with GOT entries from other objects. That
means that if prom_init.o references, say, _end via some GOT
relocation, and some other object also references _end via a GOT
relocation, the GOT entry for _end may be in the range
__prom_init_toc_start to __prom_init_toc_end and if the kernel does
something special to GOT/TOC entries in that range then the value of
_end as seen by objects other than prom_init.o will be affected. On
the other hand the GOT entry for _end may not be in the range
__prom_init_toc_start to __prom_init_toc_end. Which way it turns out
is deterministic but a detail of linker operation that should not be
relied on.

A feature of ld.bfd is that input .toc (and .got) sections matching
one linker input section statement may be sorted, to put entries used
by small-model code first, near the toc base. This is why scripts for
powerpc64 normally use *(.got .toc) rather than *(.got) *(.toc), since
the first form allows more freedom to sort.

Another feature of ld.bfd is that indirect addressing sequences using
the GOT/TOC may be edited by the linker to relative addressing. In
many cases relative addressing would be emitted by gcc for
-mcmodel=medium if you appropriately decorate variable declarations
with non-default visibility.

The original patch is here:
https://lore.kernel.org/linuxppc-dev/[email protected]/

Signed-off-by: Alan Modra <[email protected]>
[aik: removed non-relocatable which is gone in 24d33ac5b8ffb]
[aik: added <=2.24 check]
[aik: because of llvm-as, kernel_toc_addr() uses "mr" instead of global register variable]
Signed-off-by: Alexey Kardashevskiy <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...

powerpc: use generic version of arch_is_kernel_initmem_freed()

The generic version of arch_is_kernel_initmem_freed() now does the same
as powerpc version.

Remove the powerpc version.

Link: https:/

powerpc: use generic version of arch_is_kernel_initmem_freed()

The generic version of arch_is_kernel_initmem_freed() now does the same
as powerpc version.

Remove the powerpc version.

Link: https://lkml.kernel.org/r/c53764eb45d41491e2b21da2e7812239897dbebb.1633001016.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <[email protected]>
Cc: Kefeng Wang <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Gerald Schaefer <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Paul Mackerras <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

powerpc: Remove in_kernel_text()

Last user of in_kernel_text() stopped using in with
commit 549e8152de80 ("powerpc: Make the 64-bit kernel as a
position-independent executable").

Generic function i

powerpc: Remove in_kernel_text()

Last user of in_kernel_text() stopped using in with
commit 549e8152de80 ("powerpc: Make the 64-bit kernel as a
position-independent executable").

Generic function is_kernel_text() does the same.

So remote it.

Signed-off-by: Christophe Leroy <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/2a3a5b6f8cc0ef4e854d7b764f66aa8d2ee270d2.1624813698.git.christophe.leroy@csgroup.eu

show more ...

maccess: make get_kernel_nofault() check for minimal type compatibility

Now that we've renamed probe_kernel_address() to get_kernel_nofault()
and made it look and behave more in line with get_user()

maccess: make get_kernel_nofault() check for minimal type compatibility

Now that we've renamed probe_kernel_address() to get_kernel_nofault()
and made it look and behave more in line with get_user(), some of the
subtle type behavior differences end up being more obvious and possibly
dangerous.

When you do

get_user(val, user_ptr);

the type of the access comes from the "user_ptr" part, and the above
basically acts as

val = *user_ptr;

by design (except, of course, for the fact that the actual dereference
is done with a user access).

Note how in the above case, the type of the end result comes from the
pointer argument, and then the value is cast to the type of 'val' as
part of the assignment.

So the type of the pointer is ultimately the more important type both
for the access itself.

But 'get_kernel_nofault()' may now _look_ similar, but it behaves very
differently. When you do

get_kernel_nofault(val, kernel_ptr);

it behaves like

val = *(typeof(val) *)kernel_ptr;

except, of course, for the fact that the actual dereference is done with
exception handling so that a faulting access is suppressed and returned
as the error code.

But note how different the casting behavior of the two superficially
similar accesses are: one does the actual access in the size of the type
the pointer points to, while the other does the access in the size of
the target, and ignores the pointer type entirely.

Actually changing get_kernel_nofault() to act like get_user() is almost
certainly the right thing to do eventually, but in the meantime this
patch adds logit to at least verify that the pointer type is compatible
with the type of the result.

In many cases, this involves just casting the pointer to 'void *' to
make it obvious that the type of the pointer is not the important part.
It's not how 'get_user()' acts, but at least the behavioral difference
is now obvious and explicit.

Cc: Christoph Hellwig <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

maccess: rename probe_kernel_address to get_kernel_nofault

Better describe what this helper does, and match the naming of
copy_from_kernel_nofault.

Also switch the argument order around, so that it

maccess: rename probe_kernel_address to get_kernel_nofault

Better describe what this helper does, and match the naming of
copy_from_kernel_nofault.

Also switch the argument order around, so that it acts and looks
like get_user().

Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

powerpc: Define arch_is_kernel_initmem_freed() for lockdep

Under certain circumstances, we hit a warning in lockdep_register_key:

if (WARN_ON_ONCE(static_obj(key)))
return;

powerpc: Define arch_is_kernel_initmem_freed() for lockdep

Under certain circumstances, we hit a warning in lockdep_register_key:

if (WARN_ON_ONCE(static_obj(key)))
return;

This occurs when the key falls into initmem that has since been freed
and can now be reused. This has been observed on boot, and under
memory pressure.

Define arch_is_kernel_initmem_freed(), which allows lockdep to
correctly identify this memory as dynamic.

This fixes a bug picked up by the powerpc64 syzkaller instance where
we hit the WARN via alloc_netdev_mqs.

Reported-by: Qian Cai <[email protected]>
Reported-by: ppc syzbot c/o Andrew Donnellan <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Signed-off-by: Daniel Axtens <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...

powerpc/64s: Remove overlaps_kvm_tmp()

kvm_tmp is now in .text and so doesn't need a special overlap check.

Signed-off-by: Michael Ellerman <[email protected]>
Signed-off-by: Michael Ellerman <mpe

powerpc/64s: Remove overlaps_kvm_tmp()

kvm_tmp is now in .text and so doesn't need a special overlap check.

Signed-off-by: Michael Ellerman <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...

powerpc/64s: Fix unrelocated interrupt trampoline address test

The recent commit got this test wrong, it declared the assembler
symbols the wrong way, and also used the wrong symbol name
(xxx_start

powerpc/64s: Fix unrelocated interrupt trampoline address test

The recent commit got this test wrong, it declared the assembler
symbols the wrong way, and also used the wrong symbol name
(xxx_start rather than start_xxx, see asm/head-64.h).

Fixes: ccd477028a ("powerpc/64s: Fix HV NMI vs HV interrupt recoverability test")
Signed-off-by: Nicholas Piggin <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>

show more ...

powerpc64: Add .opd based function descriptor dereference

We are moving towards separate kernel and module function descriptor
dereference callbacks. This patch enables it for powerpc64.

For pointe

powerpc64: Add .opd based function descriptor dereference

We are moving towards separate kernel and module function descriptor
dereference callbacks. This patch enables it for powerpc64.

For pointers that belong to the kernel
- Added __start_opd and __end_opd pointers, to track the kernel
.opd section address range;

- Added dereference_kernel_function_descriptor(). Now we
will dereference only function pointers that are within
[__start_opd, __end_opd);

For pointers that belong to a module
- Added dereference_module_function_descriptor() to handle module
function descriptor dereference. Now we will dereference only
pointers that are within [module->opd.start, module->opd.end).

Link: http://lkml.kernel.org/r/[email protected]
To: Tony Luck <[email protected]>
To: Fenghua Yu <[email protected]>
To: Helge Deller <[email protected]>
To: Benjamin Herrenschmidt <[email protected]>
To: Paul Mackerras <[email protected]>
To: Michael Ellerman <[email protected]>
To: James Bottomley <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Jessica Yu <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Sergey Senozhatsky <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Signed-off-by: Sergey Senozhatsky <[email protected]>
Tested-by: Santosh Sivaraj <[email protected]> #powerpc
Signed-off-by: Petr Mladek <[email protected]>

show more ...

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <[email protected]>
Reviewed-by: Philippe Ombredanne <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

powerpc/kprobes: Blacklist exception handlers

Introduce __head_end to mark end of the early fixed sections and use it to
blacklist all exception handlers from kprobes.

mpe: We do not need to do any

powerpc/kprobes: Blacklist exception handlers

Introduce __head_end to mark end of the early fixed sections and use it to
blacklist all exception handlers from kprobes.

mpe: We do not need to do anything special for relocatable kernels, where the
exception vectors are split from the main kernel, as the split vectors are
already excluded by the check for kernel_text_address().

Signed-off-by: Naveen N. Rao <[email protected]>
[mpe: Move __head_end outside #ifdef 64-bit to unbreak the 32-bit build]
Signed-off-by: Michael Ellerman <[email protected]>

show more ...

powerpc: Define and use PPC64_ELF_ABI_v2/v1

We're approaching 20 locations where we need to check for ELF ABI v2.
That's fine, except the logic is a bit awkward, because we have to check
that _CALL_

powerpc: Define and use PPC64_ELF_ABI_v2/v1

We're approaching 20 locations where we need to check for ELF ABI v2.
That's fine, except the logic is a bit awkward, because we have to check
that _CALL_ELF is defined and then what its value is.

So check it once in asm/types.h and define PPC64_ELF_ABI_v2 when ELF ABI
v2 is detected.

We also have a few places where what we're really trying to check is
that we are using the 64-bit v1 ABI, ie. function descriptors. So also
add a #define for that, which simplifies several checks.

Signed-off-by: Naveen N. Rao <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>

show more ...

powerpc: Create a helper for getting the kernel toc value

Move the logic to work out the kernel toc pointer into a header. This is
a good cleanup, and also means we can use it elsewhere in future.

powerpc: Create a helper for getting the kernel toc value

Move the logic to work out the kernel toc pointer into a header. This is
a good cleanup, and also means we can use it elsewhere in future.

Reviewed-by: Kamalesh Babulal <[email protected]>
Reviewed-by: Torsten Duwe <[email protected]>
Reviewed-by: Balbir Singh <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Tested-by: Kamalesh Babulal <[email protected]>

show more ...

KVM guest: Make pv trampoline code executable

Our PV guest patching code assembles chunks of instructions on the fly when it
encounters more complicated instructions to hijack. These instructions ne

KVM guest: Make pv trampoline code executable

Our PV guest patching code assembles chunks of instructions on the fly when it
encounters more complicated instructions to hijack. These instructions need
to live in a section that we don't mark as non-executable, as otherwise we
fault when jumping there.

Right now we put it into the .bss section where it automatically gets marked
as non-executable. Add a check to the NX setting function to ensure that we
leave these particular pages executable.

Signed-off-by: Alexander Graf <[email protected]>

show more ...

powerpc: Fix ABIv2 issue with dereference_function_descriptor

Don't try and dereference a function descriptor on ABIv2.

Signed-off-by: Anton Blanchard <[email protected]>