From: Arvind Sankar <nivedita@alum.mit.edu>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org
Cc: Nick Desaulniers <ndesaulniers@google.com>,
Fangrui Song <maskray@google.com>,
Dmitry Golovin <dima@golovin.in>,
clang-built-linux@googlegroups.com,
Ard Biesheuvel <ardb@kernel.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Daniel Kiper <daniel.kiper@oracle.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH 3/4] x86/boot: Remove runtime relocations from head_{32,64}.S
Date: Sun, 24 May 2020 17:28:15 -0400 [thread overview]
Message-ID: <20200524212816.243139-4-nivedita@alum.mit.edu> (raw)
In-Reply-To: <CAKwvOd=qB+EoJwfAYUA9Hg7f9op4Q4W+TDnht8pLRG5bPX=29Q@mail.gmail.com>
The BFD linker generates runtime relocations for z_input_len and
z_output_len, even though they are absolute symbols.
Work around this 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 runtime relocations in the head code and
allows us to drop the -z noreloc-overflow flag to the linker.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
---
arch/x86/boot/compressed/Makefile | 8 --------
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, 16 insertions(+), 19 deletions(-)
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index aa9ed814e5fa..d3e882e855ee 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -49,15 +49,7 @@ 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
hostprogs := mkpiggy
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index 66657bb99aae..064e895bad92 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -193,18 +193,17 @@ 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@GOTOFF(%ebx) /* decompressed length, end of relocs */
+ pushl %ebp /* output address */
+ pushl input_len@GOTOFF(%ebx) /* input_len */
leal input_data@GOTOFF(%ebx), %eax
- pushl %eax /* input_data */
+ pushl %eax /* input_data */
leal boot_heap@GOTOFF(%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 f6ba32cd5702..6e4704b6a94e 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -508,9 +508,9 @@ 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 7e01248765b2..52aa56cdbacc 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)
--
2.26.2
next prev parent reply other threads:[~2020-05-24 21:28 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-01 8:42 [PATCH] x86/boot: allow a relocatable kernel to be linked with lld Dmitry Golovin
2020-05-02 3:43 ` Nathan Chancellor
2020-05-15 18:50 ` Borislav Petkov
[not found] ` <602331589572661@mail.yandex.ru>
2020-05-17 19:44 ` Fangrui Song
2020-05-17 20:25 ` Arvind Sankar
2020-05-18 19:10 ` Nick Desaulniers
2020-05-24 21:28 ` [PATCH 0/4] x86/boot: Remove runtime relocations from compressed kernel Arvind Sankar
2020-05-25 7:10 ` Ard Biesheuvel
2020-05-25 22:59 ` [PATCH v2 " Arvind Sankar
2020-05-26 12:29 ` Sedat Dilek
2020-05-26 12:30 ` Ard Biesheuvel
2020-05-26 12:33 ` Sedat Dilek
2020-05-26 12:44 ` Sedat Dilek
2020-05-26 14:47 ` Arvind Sankar
2020-05-26 14:50 ` Sedat Dilek
2020-05-26 15:36 ` Arvind Sankar
2020-05-26 15:38 ` Sedat Dilek
2020-05-27 6:26 ` Sedat Dilek
2020-05-26 14:48 ` Sedat Dilek
2020-05-26 14:55 ` Sedat Dilek
2020-05-26 15:07 ` Sedat Dilek
2020-05-26 15:31 ` Arvind Sankar
2020-05-27 6:24 ` Sedat Dilek
2020-05-26 16:18 ` Sedat Dilek
2020-05-25 22:59 ` [PATCH v2 1/4] x86/boot: Add .text.* to setup.ld Arvind Sankar
2020-05-25 22:59 ` [PATCH v2 2/4] x86/boot: Remove run-time relocations from .head.text code Arvind Sankar
2020-05-25 22:59 ` [PATCH v2 3/4] x86/boot: Remove runtime relocations from head_{32,64}.S Arvind Sankar
2020-05-25 22:59 ` [PATCH v2 4/4] x86/boot: Check that there are no runtime relocations Arvind Sankar
2020-05-26 6:11 ` Ard Biesheuvel
2020-05-26 15:16 ` Arvind Sankar
2020-05-26 17:13 ` Fangrui Song
2020-05-26 19:14 ` Arvind Sankar
2020-08-06 11:19 ` Andy Shevchenko
2020-08-06 16:12 ` Arvind Sankar
2020-05-26 0:37 ` [PATCH 0/4] x86/boot: Remove runtime relocations from compressed kernel Fangrui Song
2020-05-24 21:28 ` [PATCH 1/4] x86/boot: Add .text.startup to setup.ld Arvind Sankar
2020-05-24 22:13 ` Fangrui Song
2020-05-24 23:00 ` Arvind Sankar
2020-05-24 23:49 ` Fangrui Song
2020-05-24 22:48 ` Brian Gerst
2020-05-24 21:28 ` [PATCH 2/4] x86/boot: Remove runtime relocations from .head.text code Arvind Sankar
2020-05-24 22:53 ` Fangrui Song
2020-05-24 23:44 ` Arvind Sankar
2020-05-25 0:55 ` Fangrui Song
2020-05-24 21:28 ` Arvind Sankar [this message]
2020-05-24 23:22 ` [PATCH 3/4] x86/boot: Remove runtime relocations from head_{32,64}.S Fangrui Song
2020-05-24 23:58 ` Arvind Sankar
2020-05-24 21:28 ` [PATCH 4/4] x86/boot: Check that there are no runtime relocations Arvind Sankar
2020-05-24 23:36 ` Fangrui Song
2020-05-24 23:57 ` Arvind Sankar
2020-05-25 6:10 ` Ard Biesheuvel
2020-05-25 16:26 ` Fangrui Song
2020-05-25 19:22 ` Arvind Sankar
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