From: Oliver O'Halloran <oohall@xxxxxxxxx>
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
the function needs to be in the .kprobes.text section, which is done by the
_KPROBE() macro. So we have to add a _KPROBE_TOC() macro, which does the TOC
setup and also puts the function in the .kprobes.text section]
Fixes: 721aeaa9fdf3 ("powerpc: Build little endian ppc64 kernel with ABIv2")
Signed-off-by: Oliver O'Halloran <oohall@xxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/ppc_asm.h | 12 ++++++++++++
arch/powerpc/kernel/misc_64.S | 4 ++--
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index dd0fc18d8103..160bb2311bbb 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -224,6 +224,16 @@ name: \
.globl name; \
name:
+#define _KPROBE_TOC(name) \
+ .section ".kprobes.text","a"; \
+ .align 2 ; \
+ .type name,@function; \
+ .globl name; \
+name: \
+0: addis r2,r12,(.TOC.-0b)@ha; \
+ addi r2,r2,(.TOC.-0b)@l; \
+ .localentry name,.-name
+
#define DOTSYM(a) a
#else
@@ -261,6 +271,8 @@ name: \
.type GLUE(.,name),@function; \
GLUE(.,name):
+#define _KPROBE_TOC(n) _KPROBE(n)
+
#define DOTSYM(a) GLUE(.,a)
#endif
diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
index db475d41b57a..415e58565745 100644
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -66,7 +66,7 @@ PPC64_CACHES:
* flush all bytes from start through stop-1 inclusive
*/
-_KPROBE(flush_icache_range)
+_KPROBE_TOC(flush_icache_range)
BEGIN_FTR_SECTION
PURGE_PREFETCHED_INS
blr
@@ -117,7 +117,7 @@ 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
--
2.14.1