FAILED: patch "[PATCH] powerpc/64: Fix flush_(d|i)cache_range() called from modules" failed to apply to 4.4-stable tree

The patch below does not apply to the 4.4-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 <[email protected]>.

thanks,

greg k-h

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

From: Oliver O'Halloran <[email protected]>
Date: Mon, 3 Apr 2017 13:25:12 +1000
Subject: [PATCH] powerpc/64: Fix flush_(d|i)cache_range() called from modules

When the kernel is compiled to use 64bit ABIv2 the _GLOBAL() macro does not include a global entry point. A function's global entry point is used when the function is called from a different TOC context and in the kernel this typically means a call from a module into the vmlinux (or vice-versa).

There are a few exported asm functions declared with _GLOBAL() and calling them from a module will likely crash the kernel since any TOC relative load will yield garbage.

flush_icache_range() and flush_dcache_range() are both exported to modules, and use the TOC, so must use _GLOBAL_TOC().

index ae179cb1bb3c..c119044cad0d 100644
@@ -67,7 +67,7 @@ PPC64_CACHES:
  *   flush all bytes from start through stop-1 inclusive
  */
 
-_GLOBAL(flush_icache_range)
+_GLOBAL_TOC(flush_icache_range)
 BEGIN_FTR_SECTION
 	PURGE_PREFETCHED_INS
 	blr

@@ -120,7 +120,7 @@ EXPORT_SYMBOL(flush_icache_range)
  *
  *    flush all bytes from start to stop-1 inclusive
  */
-_GLOBAL(flush_dcache_range)
+_GLOBAL_TOC(flush_dcache_range)
 
 /*
  * Flush the data cache to memory 

Hi Greg,

Here's a backport to 4.4 at least, and probably earlier. Do you want a separate backport patch for each stable tree?

cheers

From: Oliver O'Halloran <[email protected]>
Date: Mon, 3 Apr 2017 13:25:12 +1000
Subject: [PATCH] powerpc/64: Fix flush_(d|i)cache_range() called from modules

commit 8f5f525d5b83f7d76a6baf9c4e94d4bf312ea7f6 upstream.

When the kernel is compiled to use 64bit ABIv2 the _GLOBAL() macro does not include a global entry point. A function's global entry point is used when the function is called from a different TOC context and in the kernel this typically means a call from a module into the vmlinux (or vice-versa).

There are a few exported asm functions declared with _GLOBAL() and calling them from a module will likely crash the kernel since any TOC relative load will yield garbage.

flush_icache_range() and flush_dcache_range() are both exported to modules, and use the TOC, so must use _GLOBAL_TOC().

[mpe: We can't use _GLOBAL_TOC() in 4.4 for flush_icache_range() because it needs to be in the .kprobes.text section, handled by the _KPROBE() macro. We don't have a _KPROBE_TOC() macro, so just open code the TOC initialisation.]

---
 arch/powerpc/kernel/misc_64.S | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

index db475d41b57a..06a1697e1fcf 100644
@@ -67,6 +67,9 @@ PPC64_CACHES:
  */
 
 _KPROBE(flush_icache_range)
+0:	addis	r2,r12,(.TOC. - 0b)@ha
+	addi	r2, r2,(.TOC. - 0b)@l
+	.localentry flush_icache_range, . - flush_icache_range
 BEGIN_FTR_SECTION
 	PURGE_PREFETCHED_INS
 	blr

@@ -117,7 +120,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
  *
  *    flush all bytes from start to stop-1 inclusive
  */
-_GLOBAL(flush_dcache_range)
+_GLOBAL_TOC(flush_dcache_range)
 
 /*
  * Flush the data cache to memory 

2.7.4

This works for me, thanks!

greg k-h