| From 7536ae874849c0bc8fdeb6efe0cedd12db960db1 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 22 Jun 2020 19:56:39 +0000 |
| Subject: x86/boot/compressed: Relax sed symbol type regex for LLVM ld.lld |
| |
| From: Ard Biesheuvel <ardb@kernel.org> |
| |
| commit bc310baf2ba381c648983c7f4748327f17324562 upstream. |
| |
| The final build stage of the x86 kernel captures some symbol |
| addresses from the decompressor binary and copies them into zoffset.h. |
| It uses sed with a regular expression that matches the address, symbol |
| type and symbol name, and mangles the captured addresses and the names |
| of symbols of interest into #define directives that are added to |
| zoffset.h |
| |
| The symbol type is indicated by a single letter, which we match |
| strictly: only letters in the set 'ABCDGRSTVW' are matched, even |
| though the actual symbol type is relevant and therefore ignored. |
| |
| Commit bc7c9d620 ("efi/libstub/x86: Force 'hidden' visibility for |
| extern declarations") made a change to the way external symbol |
| references are classified, resulting in 'startup_32' now being |
| emitted as a hidden symbol. This prevents the use of GOT entries to |
| refer to this symbol via its absolute address, which recent toolchains |
| (including Clang based ones) already avoid by default, making this |
| change a no-op in the majority of cases. |
| |
| However, as it turns out, the LLVM linker classifies such hidden |
| symbols as symbols with static linkage in fully linked ELF binaries, |
| causing tools such as NM to output a lowercase 't' rather than an upper |
| case 'T' for the type of such symbols. Since our sed expression only |
| matches upper case letters for the symbol type, the line describing |
| startup_32 is disregarded, resulting in a build error like the following |
| |
| arch/x86/boot/header.S:568:18: error: symbol 'ZO_startup_32' can not be |
| undefined in a subtraction expression |
| init_size: .long (0x00000000008fd000 - ZO_startup_32 + |
| (((0x0000000001f6361c + ((0x0000000001f6361c >> 8) + 65536) |
| - 0x00000000008c32e5) + 4095) & ~4095)) # kernel initialization size |
| |
| Given that we are only interested in the value of the symbol, let's match |
| any character in the set 'a-zA-Z' instead. |
| |
| Signed-off-by: Ard Biesheuvel <ardb@kernel.org> |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| Tested-by: Nathan Chancellor <natechancellor@gmail.com> |
| Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| arch/x86/boot/Makefile | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile |
| index 1c060748c813e..f38ffcc610d20 100644 |
| --- a/arch/x86/boot/Makefile |
| +++ b/arch/x86/boot/Makefile |
| @@ -87,7 +87,7 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE |
| |
| SETUP_OBJS = $(addprefix $(obj)/,$(setup-y)) |
| |
| -sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [ABCDGRSTVW] \(startup_32\|startup_64\|efi32_stub_entry\|efi64_stub_entry\|efi_pe_entry\|input_data\|_end\|_ehead\|_text\|z_.*\)$$/\#define ZO_\2 0x\1/p' |
| +sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|startup_64\|efi32_stub_entry\|efi64_stub_entry\|efi_pe_entry\|input_data\|_end\|_ehead\|_text\|z_.*\)$$/\#define ZO_\2 0x\1/p' |
| |
| quiet_cmd_zoffset = ZOFFSET $@ |
| cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@ |
| -- |
| 2.25.1 |
| |
