Patch "powerpc/asm: Add a patch_site macro & helpers for patching instructions" has been added to the 4.4-stable tree

[gregkh at linuxfoundation.org]

This is a note to let you know that I've just added the patch titled

    powerpc/asm: Add a patch_site macro & helpers for patching instructions

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-asm-add-a-patch_site-macro-helpers-for-patching-instructions.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From foo at baz Mon 29 Apr 2019 11:38:37 AM CEST
From: Michael Ellerman <mpe at ellerman.id.au>
Date: Mon, 22 Apr 2019 00:20:24 +1000
Subject: powerpc/asm: Add a patch_site macro & helpers for patching instructions
To: stable at vger.kernel.org, gregkh at linuxfoundation.org
Cc: linuxppc-dev at ozlabs.org, diana.craciun at nxp.com, msuchanek at suse.de, npiggin at gmail.com, christophe.leroy at c-s.fr
Message-ID: <20190421142037.21881-40-mpe at ellerman.id.au>

From: Michael Ellerman <mpe at ellerman.id.au>

commit 06d0bbc6d0f56dacac3a79900e9a9a0d5972d818 upstream.

Add a macro and some helper C functions for patching single asm
instructions.

The gas macro means we can do something like:

  1:	nop
  	patch_site 1b, patch__foo

Which is less visually distracting than defining a GLOBAL symbol at 1,
and also doesn't pollute the symbol table which can confuse eg. perf.

These are obviously similar to our existing feature sections, but are
not automatically patched based on CPU/MMU features, rather they are
designed to be manually patched by C code at some arbitrary point.

Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 arch/powerpc/include/asm/code-patching-asm.h |   18 ++++++++++++++++++
 arch/powerpc/include/asm/code-patching.h     |    2 ++
 arch/powerpc/lib/code-patching.c             |   16 ++++++++++++++++
 3 files changed, 36 insertions(+)
 create mode 100644 arch/powerpc/include/asm/code-patching-asm.h

--- /dev/null
+++ b/arch/powerpc/include/asm/code-patching-asm.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright 2018, Michael Ellerman, IBM Corporation.
+ */
+#ifndef _ASM_POWERPC_CODE_PATCHING_ASM_H
+#define _ASM_POWERPC_CODE_PATCHING_ASM_H
+
+/* Define a "site" that can be patched */
+.macro patch_site label name
+	.pushsection ".rodata"
+	.balign 4
+	.global \name
+\name:
+	.4byte	\label - .
+	.popsection
+.endm
+
+#endif /* _ASM_POWERPC_CODE_PATCHING_ASM_H */
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h
@@ -28,6 +28,8 @@ unsigned int create_cond_branch(const un
 				unsigned long target, int flags);
 int patch_branch(unsigned int *addr, unsigned long target, int flags);
 int patch_instruction(unsigned int *addr, unsigned int instr);
+int patch_instruction_site(s32 *addr, unsigned int instr);
+int patch_branch_site(s32 *site, unsigned long target, int flags);
 
 int instr_is_relative_branch(unsigned int instr);
 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -32,6 +32,22 @@ int patch_branch(unsigned int *addr, uns
 	return patch_instruction(addr, create_branch(addr, target, flags));
 }
 
+int patch_branch_site(s32 *site, unsigned long target, int flags)
+{
+	unsigned int *addr;
+
+	addr = (unsigned int *)((unsigned long)site + *site);
+	return patch_instruction(addr, create_branch(addr, target, flags));
+}
+
+int patch_instruction_site(s32 *site, unsigned int instr)
+{
+	unsigned int *addr;
+
+	addr = (unsigned int *)((unsigned long)site + *site);
+	return patch_instruction(addr, instr);
+}
+
 unsigned int create_branch(const unsigned int *addr,
 			   unsigned long target, int flags)
 {


Patches currently in stable-queue which might be from mpe at ellerman.id.au are

queue-4.4/powerpc-64s-add-support-for-a-store-forwarding-barrier-at-kernel-entry-exit.patch
queue-4.4/powerpc-64-make-stf-barrier-ppc_book3s_64-specific.patch
queue-4.4/powerpc-pseries-set-or-clear-security-feature-flags.patch
queue-4.4/powerpc-fsl-fix-spectre_v2-mitigations-reporting.patch
queue-4.4/powerpc-64s-patch-barrier_nospec-in-modules.patch
queue-4.4/powerpc-pseries-support-firmware-disable-of-rfi-flush.patch
queue-4.4/powerpc-rfi-flush-call-setup_rfi_flush-after-lpm-migration.patch
queue-4.4/powerpc-pseries-query-hypervisor-for-count-cache-flush-settings.patch
queue-4.4/powerpc-powernv-set-or-clear-security-feature-flags.patch
queue-4.4/powerpc-64s-add-support-for-software-count-cache-flush.patch
queue-4.4/powerpc64s-show-ori31-availability-in-spectre_v1-sysfs-file-not-v2.patch
queue-4.4/powerpc-fsl-flush-the-branch-predictor-at-each-kernel-entry-64bit.patch
queue-4.4/powerpc-fsl-update-spectre-v2-reporting.patch
queue-4.4/powerpc-64s-wire-up-cpu_show_spectre_v2.patch
queue-4.4/powerpc-64-make-meltdown-reporting-book3s-64-specific.patch
queue-4.4/powerpc-rfi-flush-make-it-possible-to-call-setup_rfi_flush-again.patch
queue-4.4/powerpc-64s-add-support-for-ori-barrier_nospec-patching.patch
queue-4.4/powerpc-use-barrier_nospec-in-copy_from_user.patch
queue-4.4/powerpc-64s-fix-section-mismatch-warnings-from-setup_rfi_flush.patch
queue-4.4/powerpc-avoid-code-patching-freed-init-sections.patch
queue-4.4/powerpc-fsl-add-macro-to-flush-the-branch-predictor.patch
queue-4.4/powerpc-xmon-add-rfi-flush-related-fields-to-paca-dump.patch
queue-4.4/powerpc-fsl-add-barrier_nospec-implementation-for-nxp-powerpc-book3e.patch
queue-4.4/powerpc-security-fix-spectre_v2-reporting.patch
queue-4.4/powerpc-add-security-feature-flags-for-spectre-meltdown.patch
queue-4.4/powerpc-powernv-use-the-security-flags-in-pnv_setup_rfi_flush.patch
queue-4.4/powerpc-64-disable-the-speculation-barrier-from-the-command-line.patch
queue-4.4/powerpc-fsl-fix-the-flush-of-branch-predictor.patch
queue-4.4/powerpc-pseries-use-the-security-flags-in-pseries_setup_rfi_flush.patch
queue-4.4/powerpc-64-add-config_ppc_barrier_nospec.patch
queue-4.4/powerpc-64s-move-cpu_show_meltdown.patch
queue-4.4/powerpc-64-use-barrier_nospec-in-syscall-entry.patch
queue-4.4/powerpc-fsl-add-nospectre_v2-command-line-argument.patch
queue-4.4/powerpc-64s-add-new-security-feature-flags-for-count-cache-flush.patch
queue-4.4/powerpc-fsl-add-infrastructure-to-fixup-branch-predictor-flush.patch
queue-4.4/powerpc-rfi-flush-differentiate-enabled-and-patched-flush-types.patch
queue-4.4/powerpc-64s-enhance-the-information-in-cpu_show_spectre_v1.patch
queue-4.4/powerpc-64-call-setup_barrier_nospec-from-setup_arch.patch
queue-4.4/powerpc-rfi-flush-always-enable-fallback-flush-on-pseries.patch
queue-4.4/powerpc-64s-improve-rfi-l1-d-cache-flush-fallback.patch
queue-4.4/powerpc-asm-add-a-patch_site-macro-helpers-for-patching-instructions.patch
queue-4.4/powerpc-pseries-add-new-h_get_cpu_characteristics-flags.patch
queue-4.4/powerpc-64s-enable-barrier_nospec-based-on-firmware-settings.patch
queue-4.4/powerpc-powernv-support-firmware-disable-of-rfi-flush.patch
queue-4.4/powerpc-rfi-flush-move-the-logic-to-avoid-a-redo-into-the-debugfs-code.patch
queue-4.4/powerpc-powernv-query-firmware-for-count-cache-flush-settings.patch
queue-4.4/powerpc-64s-wire-up-cpu_show_spectre_v1.patch
queue-4.4/powerpc-64s-add-barrier_nospec.patch
queue-4.4/powerpc-64s-enhance-the-information-in-cpu_show_meltdown.patch
queue-4.4/powerpc-move-default-security-feature-flags.patch
queue-4.4/powerpc-pseries-fix-clearing-of-security-feature-flags.patch
queue-4.4/powerpc-pseries-restore-default-security-feature-flags-on-setup.patch