On 12/21/23 14:07, Masahiro Yamada wrote:
On Thu, Nov 23, 2023 at 7:18 AM <deller@xxxxxxxxxx> wrote:
From: Helge Deller <deller@xxxxxx>
On 64-bit architectures without CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
(e.g. ppc64, ppc64le, parisc, s390x,...) the __KSYM_REF() macro stores
64-bit pointers into the __ksymtab* sections.
Make sure that the start of those sections is 64-bit aligned in the vmlinux
executable, otherwise unaligned memory accesses may happen at runtime.
Are you solving a real problem?
Not any longer.
I faced a problem on parisc when neither #1 and #3 were applied
because of a buggy unalignment exception handler. But this is
not something which I would count a "real generic problem".
1/4 already ensures the proper alignment of __ksymtab*, doesn't it?
Yes, it does.
...
So, my understanding is this patch is unneeded.
Yes, it's not required and I'm fine if we drop it.
But regarding __kcrctab:
@@ -498,6 +501,7 @@
} \
\
/* Kernel symbol table: Normal symbols */ \
+ . = ALIGN(4); \
__kcrctab : AT(ADDR(__kcrctab) - LOAD_OFFSET) { \
__start___kcrctab = .; \
KEEP(*(SORT(___kcrctab+*))) \
I think this patch would be beneficial to get proper alignment:
diff --git a/include/linux/export-internal.h b/include/linux/export-internal.h
index cd253eb51d6c..d445705ac13c 100644
--- a/include/linux/export-internal.h
+++ b/include/linux/export-internal.h
@@ -64,6 +64,7 @@
#define SYMBOL_CRC(sym, crc, sec) \
asm(".section \"___kcrctab" sec "+" #sym "\",\"a\"" "\n" \
+ ".balign 4" "\n" \
"__crc_" #sym ":" "\n" \
".long " #crc "\n" \
".previous" "\n")
Helge
