linux.git/arch/powerpc/kernel/security.c, branch v7.2-rc2

powerpc: use sysfs_emit{_at} in sysfs show functions

2026-06-02T05:54:32+00:00

Replace sprintf() with sysfs_emit() and sysfs_emit_at() in sysfs show
functions, which are preferred for formatting sysfs output because they
provide safer bounds checking.

While the current code only emits strings that fit easily within
PAGE_SIZE, use sysfs_emit() and sysfs_emit_at() to follow secure coding
best practices.

This is a mechanical cleanup with a few simple edge cases:

- In domains_show(), drop the redundant n < 0 check since neither
  sprintf() nor sysfs_emit() return negative values.

- In powercap_show() and psr_show(), also drop the dead ret < 0 checks.

- In ps3_fw_version_show(), normalize the output by adding a terminating
  newline as suggested by checkpatch.

- In vio's modalias_show(), replace the deprecated strcpy() [1] followed
  by strlen() with sysfs_emit().

Leave validate_show() and the variable-length hv-gpci helpers unchanged
since they already have explicit bounds handling, and converting those
would be more than a mechanical conversion.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy

Signed-off-by: Thorsten Blum 
Reviewed-by: Christophe Leroy (CS GROUP) 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20260524130002.793476-2-thorsten.blum@linux.dev

asm-generic: introduce text-patching.h

2024-11-07T22:25:15+00:00

Several architectures support text patching, but they name the header
files that declare patching functions differently.

Make all such headers consistently named text-patching.h and add an empty
header in asm-generic for architectures that do not support text patching.

Link: https://lkml.kernel.org/r/20241023162711.2579610-4-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) 
Reviewed-by: Christoph Hellwig 
Acked-by: Geert Uytterhoeven  # m68k
Acked-by: Arnd Bergmann 
Reviewed-by: Luis Chamberlain 
Tested-by: kdevops 
Cc: Andreas Larsson 
Cc: Andy Lutomirski 
Cc: Ard Biesheuvel 
Cc: Borislav Petkov (AMD) 
Cc: Brian Cain 
Cc: Catalin Marinas 
Cc: Christophe Leroy 
Cc: Dave Hansen 
Cc: Dinh Nguyen 
Cc: Guo Ren 
Cc: Helge Deller 
Cc: Huacai Chen 
Cc: Ingo Molnar 
Cc: Johannes Berg 
Cc: John Paul Adrian Glaubitz 
Cc: Kent Overstreet 
Cc: Liam R. Howlett 
Cc: Mark Rutland 
Cc: Masami Hiramatsu (Google) 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Oleg Nesterov 
Cc: Palmer Dabbelt 
Cc: Peter Zijlstra 
Cc: Richard Weinberger 
Cc: Russell King 
Cc: Song Liu 
Cc: Stafford Horne 
Cc: Steven Rostedt (Google) 
Cc: Suren Baghdasaryan 
Cc: Thomas Bogendoerfer 
Cc: Thomas Gleixner 
Cc: Uladzislau Rezki (Sony) 
Cc: Vineet Gupta 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

powerpc/security: Fix Speculation_Store_Bypass reporting on Power10

2023-07-09T23:47:47+00:00

Nageswara reported that /proc/self/status was showing "vulnerable" for
the Speculation_Store_Bypass feature on Power10, eg:

  $ grep Speculation_Store_Bypass: /proc/self/status
  Speculation_Store_Bypass:       vulnerable

But at the same time the sysfs files, and lscpu, were showing "Not
affected".

This turns out to simply be a bug in the reporting of the
Speculation_Store_Bypass, aka. PR_SPEC_STORE_BYPASS, case.

When SEC_FTR_STF_BARRIER was added, so that firmware could communicate
the vulnerability was not present, the code in ssb_prctl_get() was not
updated to check the new flag.

So add the check for SEC_FTR_STF_BARRIER being disabled. Rather than
adding the new check to the existing if block and expanding the comment
to cover both cases, rewrite the three cases to be separate so they can
be commented separately for clarity.

Fixes: 84ed26fd00c5 ("powerpc/security: Add a security feature for STF barrier")
Cc: stable@vger.kernel.org # v5.14+
Reported-by: Nageswara R Sastry 
Tested-by: Nageswara R Sastry 
Reviewed-by: Russell Currey 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/20230517074945.53188-1-mpe@ellerman.id.au

powerpc: Remove CONFIG_PPC_FSL_BOOK3E

2022-09-26T13:00:13+00:00

CONFIG_PPC_FSL_BOOK3E is redundant with CONFIG_PPC_E500.

Remove it.

And rename five files accordingly.

Signed-off-by: Christophe Leroy 
[mpe: Rename include guards to match new file names]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/795cb93b88c9a0279289712e674f39e3b108a1b4.1663606876.git.christophe.leroy@csgroup.eu

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

2022-08-26T01:02:20+00:00

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 
Link: https://lore.kernel.org/r/20220818050659.187181-1-mpe@ellerman.id.au

powerpc: add link stack flush mitigation status in debugfs.

2022-01-31T02:45:23+00:00

The link stack flush status is not visible in debugfs. It can be enabled
even when count cache flush is disabled. Add separate file for its
status.

Signed-off-by: Michal Suchanek 
[mpe: Update for change to link_stack_flush_type]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20191127220959.6208-1-msuchanek@suse.de

powerpc/kernel: Add __init attribute to eligible functions

2021-12-23T11:33:10+00:00

Some functions defined in `arch/powerpc/kernel` (and one in `arch/powerpc/
kexec`) are deserving of an `__init` macro attribute. These functions are
only called by other initialization functions and therefore should inherit
the attribute.
Also, change function declarations in header files to include `__init`.

Signed-off-by: Nick Child 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20211216220035.605465-2-nick.child@ibm.com

powerpc/security: Add a helper to query stf_barrier type

2021-10-07T08:52:58+00:00

Add a helper to return the stf_barrier type for the current processor.

Signed-off-by: Naveen N. Rao 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/3bd5d7f96ea1547991ac2ce3137dc2b220bae285.1633464148.git.naveen.n.rao@linux.vnet.ibm.com

powerpc: rename powerpc_debugfs_root to arch_debugfs_dir

2021-08-13T12:04:26+00:00

No functional change in this patch. arch_debugfs_dir is the generic kernel
name declared in linux/debugfs.h for arch-specific debugfs directory.
Architectures like x86/s390 already use the name. Rename powerpc
specific powerpc_debugfs_root to arch_debugfs_dir.

Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210812132831.233794-2-aneesh.kumar@linux.ibm.com

powerpc/security: Add a security feature for STF barrier

2021-06-21T11:13:19+00:00

Rather than tying this mitigation to RFI L1D flush requirement, add a
new bit for it.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20210503130243.891868-3-npiggin@gmail.com