The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b45ba4a51cde29b2939365ef0c07ad34c8321789 Mon Sep 17 00:00:00 2001

From: Christophe Leroy christophe.leroy@c-s.fr Date: Mon, 1 Oct 2018 12:21:10 +0000 Subject: [PATCH] powerpc/lib: fix book3s/32 boot failure due to code patching

Commit 51c3c62b58b3 ("powerpc: Avoid code patching freed init sections") accesses 'init_mem_is_free' flag too early, before the kernel is relocated. This provokes early boot failure (before the console is active).

As it is not necessary to do this verification that early, this patch moves the test into patch_instruction() instead of __patch_instruction().

This modification also has the advantage of avoiding unnecessary remappings.

Fixes: 51c3c62b58b3 ("powerpc: Avoid code patching freed init sections") Cc: stable@vger.kernel.org # 4.13+ Signed-off-by: Christophe Leroy christophe.leroy@c-s.fr Signed-off-by: Michael Ellerman mpe@ellerman.id.au

diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index 6ae2777c220d..5ffee298745f 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -28,12 +28,6 @@ static int __patch_instruction(unsigned int *exec_addr, unsigned int instr, { int err;

- /* Make sure we aren't patching a freed init section */ - if (init_mem_is_free && init_section_contains(exec_addr, 4)) { - pr_debug("Skipping init section patching addr: 0x%px\n", exec_addr); - return 0; - } - __put_user_size(instr, patch_addr, 4, err); if (err) return err; @@ -148,7 +142,7 @@ static inline int unmap_patch_area(unsigned long addr) return 0; }

-int patch_instruction(unsigned int *addr, unsigned int instr) +static int do_patch_instruction(unsigned int *addr, unsigned int instr) { int err; unsigned int *patch_addr = NULL; @@ -188,12 +182,22 @@ out: } #else /* !CONFIG_STRICT_KERNEL_RWX */

-int patch_instruction(unsigned int *addr, unsigned int instr) +static int do_patch_instruction(unsigned int *addr, unsigned int instr) { return raw_patch_instruction(addr, instr); }

#endif /* CONFIG_STRICT_KERNEL_RWX */ + +int patch_instruction(unsigned int *addr, unsigned int instr) +{ + /* Make sure we aren't patching a freed init section */ + if (init_mem_is_free && init_section_contains(addr, 4)) { + pr_debug("Skipping init section patching addr: 0x%px\n", addr); + return 0; + } + return do_patch_instruction(addr, instr); +} NOKPROBE_SYMBOL(patch_instruction);

int patch_branch(unsigned int *addr, unsigned long target, int flags)