Re: [PATCH] powerpc: module: fix TOC symbol CRC
From: Anton Blanchard <hidden>
Date: 2014-06-18 23:44:11
Hi Laurent,
The commit 71ec7c55ed91 introduced the magic symbol ".TOC." for ELFv2 ABI. This symbol is built manually and has no CRC value computed. A zero value is put in the CRC section to avoid modpost complaining about a missing CRC. Unfortunately, this breaks the kernel module loading when the kernel is relocated (kdump case for instance) because of the relocation applied to the kcrctab values. This patch compute a CRC value for the TOC symbol which will match the one compute by the kernel when it is relocated - aka '0 - relocate_start' done in maybe_relocated called by check_version (module.c).
Adding Rusty since he maintains the module loader code. Anton
quoted hunk ↗ jump to hunk
Signed-off-by: Laurent Dufour <redacted> Cc: Anton Blanchard <redacted> --- arch/powerpc/kernel/module_64.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)diff --git a/arch/powerpc/kernel/module_64.cb/arch/powerpc/kernel/module_64.c index 077d2ce..a80c933 100644--- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c@@ -315,8 +315,15 @@ static void dedotify_versions(structmodversion_info *vers, struct modversion_info *end; for (end = (void *)vers + size; vers < end; vers++) - if (vers->name[0] == '.') + if (vers->name[0] == '.') { memmove(vers->name, vers->name+1, strlen(vers->name)); + /* The TOC symbol has no CRC computed. To avoid CRC + * check failing, we must force it to the expected + * value (see CRC check in module.c). + */ + if (!strcmp(vers->name, "TOC.")) + vers->crc = -(unsigned long)reloc_start; + } } /* Undefined symbols which refer to .funcname, hack to funcname (or .TOC.) */