From 46176b4f6bac19454b7b5c35f68594b85850a600 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 26 May 2009 14:42:40 +0900 Subject: [PATCH] x86, relocs: ignore R_386_NONE in kernel relocation entries For relocatable 32bit kernels, boot/compressed/relocs.c processes relocation entries in the kernel image and appends it to the kernel image such that boot/compressed/head_32.S can relocate the kernel. The kernel image is one statically linked object and only uses two relocation types - R_386_PC32 and R_386_32, of the two only the latter needs massaging during kernel relocation and thus handled by relocs. R_386_PC32 is ignored and all other relocation types are considered error. When the target of a relocation resides in a discarded section, binutils doesn't throw away the relocation record but nullifies it by changing it to R_386_NONE, which unfortunately makes relocs fail. The problem was triggered by yet out-of-tree x86 stack unwind patches but given the binutils behavior, ignoring R_386_NONE is the right thing to do. The problem has been tracked down to binutils behavior by Jan Beulich. [ Impact: fix build with certain binutils by ignoring R_386_NONE ] Signed-off-by: Tejun Heo Cc: Jan Beulich Cc: Ingo Molnar LKML-Reference: <4A1B8150.40702@kernel.org> Signed-off-by: H. Peter Anvin --- arch/x86/boot/compressed/relocs.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/boot/compressed/relocs.c b/arch/x86/boot/compressed/relocs.c index 857e492c571e..bbeb0c3fbd90 100644 --- a/arch/x86/boot/compressed/relocs.c +++ b/arch/x86/boot/compressed/relocs.c @@ -504,8 +504,11 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym)) if (sym->st_shndx == SHN_ABS) { continue; } - if (r_type == R_386_PC32) { - /* PC relative relocations don't need to be adjusted */ + if (r_type == R_386_NONE || r_type == R_386_PC32) { + /* + * NONE can be ignored and and PC relative + * relocations don't need to be adjusted. + */ } else if (r_type == R_386_32) { /* Visit relocations that need to be adjusted */ -- 2.20.1