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Date: Fri, 14 Aug 2020 15:23:38 -0000
From: "tip-bot2 for Arvind Sankar" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Arvind Sankar <nivedita@...m.mit.edu>,
Kees Cook <keescook@...omium.org>,
Ingo Molnar <mingo@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Sedat Dilek <sedat.dilek@...il.com>,
Ard Biesheuvel <ardb@...nel.org>,
Fangrui Song <maskray@...gle.com>, x86 <x86@...nel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: [tip: x86/boot] x86/boot: Remove run-time relocations from head_{32,64}.S
The following commit has been merged into the x86/boot branch of tip:
Commit-ID: 3f086189cd3641d212949ff044d8e4486c93d55e
Gitweb: https://git.kernel.org/tip/3f086189cd3641d212949ff044d8e4486c93d55e
Author: Arvind Sankar <nivedita@...m.mit.edu>
AuthorDate: Fri, 31 Jul 2020 16:07:50 -07:00
Committer: Ingo Molnar <mingo@...nel.org>
CommitterDate: Fri, 14 Aug 2020 12:52:35 +02:00
x86/boot: Remove run-time relocations from head_{32,64}.S
The BFD linker generates run-time relocations for z_input_len and
z_output_len, even though they are absolute symbols.
This is fixed for binutils-2.35 [1]. Work around this for earlier
versions by defining two variables input_len and output_len in addition
to the symbols, and use them via position-independent references.
This eliminates the last two run-time relocations in the head code and
allows us to drop the -z noreloc-overflow flag to the linker.
Move the -pie and --no-dynamic-linker LDFLAGS to LDFLAGS_vmlinux instead
of KBUILD_LDFLAGS. There shouldn't be anything else getting linked, but
this is the more logical location for these flags, and modversions might
call the linker if an EXPORT_SYMBOL is left over accidentally in one of
the decompressors.
[1] https://sourceware.org/bugzilla/show_bug.cgi?id=25754
Signed-off-by: Arvind Sankar <nivedita@...m.mit.edu>
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Tested-by: Nick Desaulniers <ndesaulniers@...gle.com>
Tested-by: Sedat Dilek <sedat.dilek@...il.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
Reviewed-by: Ard Biesheuvel <ardb@...nel.org>
Reviewed-by: Fangrui Song <maskray@...gle.com>
Link: https://lore.kernel.org/r/20200731230820.1742553-7-keescook@chromium.org
---
arch/x86/boot/compressed/Makefile | 12 ++----------
arch/x86/boot/compressed/head_32.S | 17 ++++++++---------
arch/x86/boot/compressed/head_64.S | 4 ++--
arch/x86/boot/compressed/mkpiggy.c | 6 ++++++
4 files changed, 18 insertions(+), 21 deletions(-)
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 7c687a7..7d25089 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -52,16 +52,8 @@ UBSAN_SANITIZE :=n
KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
# Compressed kernel should be built as PIE since it may be loaded at any
# address by the bootloader.
-ifeq ($(CONFIG_X86_32),y)
-KBUILD_LDFLAGS += $(call ld-option, -pie) $(call ld-option, --no-dynamic-linker)
-else
-# To build 64-bit compressed kernel as PIE, we disable relocation
-# overflow check to avoid relocation overflow error with a new linker
-# command-line option, -z noreloc-overflow.
-KBUILD_LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \
- && echo "-z noreloc-overflow -pie --no-dynamic-linker")
-endif
-LDFLAGS_vmlinux := -T
+LDFLAGS_vmlinux := $(call ld-option, -pie) $(call ld-option, --no-dynamic-linker)
+LDFLAGS_vmlinux += -T
hostprogs := mkpiggy
HOST_EXTRACFLAGS += -I$(srctree)/tools/include
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index 8c1a4f5..659fad5 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -178,18 +178,17 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
/*
* Do the extraction, and jump to the new kernel..
*/
- /* push arguments for extract_kernel: */
- pushl $z_output_len /* decompressed length, end of relocs */
+ /* push arguments for extract_kernel: */
- pushl %ebp /* output address */
-
- pushl $z_input_len /* input_len */
+ pushl output_len@...OFF(%ebx) /* decompressed length, end of relocs */
+ pushl %ebp /* output address */
+ pushl input_len@...OFF(%ebx) /* input_len */
leal input_data@...OFF(%ebx), %eax
- pushl %eax /* input_data */
+ pushl %eax /* input_data */
leal boot_heap@...OFF(%ebx), %eax
- pushl %eax /* heap area */
- pushl %esi /* real mode pointer */
- call extract_kernel /* returns kernel location in %eax */
+ pushl %eax /* heap area */
+ pushl %esi /* real mode pointer */
+ call extract_kernel /* returns kernel location in %eax */
addl $24, %esp
/*
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 1142909..9e46729 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -534,9 +534,9 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
movq %rsi, %rdi /* real mode address */
leaq boot_heap(%rip), %rsi /* malloc area for uncompression */
leaq input_data(%rip), %rdx /* input_data */
- movl $z_input_len, %ecx /* input_len */
+ movl input_len(%rip), %ecx /* input_len */
movq %rbp, %r8 /* output target address */
- movl $z_output_len, %r9d /* decompressed length, end of relocs */
+ movl output_len(%rip), %r9d /* decompressed length, end of relocs */
call extract_kernel /* returns kernel location in %rax */
popq %rsi
diff --git a/arch/x86/boot/compressed/mkpiggy.c b/arch/x86/boot/compressed/mkpiggy.c
index 7e01248..52aa56c 100644
--- a/arch/x86/boot/compressed/mkpiggy.c
+++ b/arch/x86/boot/compressed/mkpiggy.c
@@ -60,6 +60,12 @@ int main(int argc, char *argv[])
printf(".incbin \"%s\"\n", argv[1]);
printf("input_data_end:\n");
+ printf(".section \".rodata\",\"a\",@progbits\n");
+ printf(".globl input_len\n");
+ printf("input_len:\n\t.long %lu\n", ilen);
+ printf(".globl output_len\n");
+ printf("output_len:\n\t.long %lu\n", (unsigned long)olen);
+
retval = 0;
bail:
if (f)
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