From: Sedat Dilek <sedat.dilek@gmail.com>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Nick Desaulniers <ndesaulniers@google.com>,
Fangrui Song <maskray@google.com>,
Dmitry Golovin <dima@golovin.in>,
Clang-Built-Linux ML <clang-built-linux@googlegroups.com>,
Ard Biesheuvel <ardb@kernel.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Daniel Kiper <daniel.kiper@oracle.com>,
Kees Cook <keescook@chromium.org>,
Nathan Chancellor <natechancellor@gmail.com>,
Arnd Bergmann <arnd@arndb.de>, "H . J . Lu" <hjl@sourceware.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 6/7] x86/boot: Remove run-time relocations from head_{32,64}.S
Date: Wed, 15 Jul 2020 10:58:00 +0200 [thread overview]
Message-ID: <CA+icZUXDoeHEcFurBVTv-JMR2xR6oj500n=fVSrN56_KOHiHcw@mail.gmail.com> (raw)
In-Reply-To: <20200715004133.1430068-7-nivedita@alum.mit.edu>
On Wed, Jul 15, 2020 at 2:41 AM Arvind Sankar <nivedita@alum.mit.edu> wrote:
>
> 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.
>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Reported breakage with LLD in previous patchset version.
- Sedat -
> [1] https://sourceware.org/bugzilla/show_bug.cgi?id=25754
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
> Reviewed-by: Fangrui Song <maskray@google.com>
> Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
> ---
> 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 c829d874dcac..ae2c0dc98a6a 100644
> --- a/arch/x86/boot/compressed/Makefile
> +++ b/arch/x86/boot/compressed/Makefile
> @@ -51,16 +51,8 @@ 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 8c1a4f5610f5..659fad53ca82 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@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 11429092c224..9e46729cf162 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 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:[~2020-07-15 8:58 UTC|newest]
Thread overview: 113+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-29 14:09 [PATCH v3 0/7] x86/boot: Remove runtime relocations from compressed kernel Arvind Sankar
2020-06-29 14:09 ` [PATCH v3 1/7] x86/boot/compressed: Move .got.plt entries out of the .got section Arvind Sankar
2020-06-29 15:48 ` Kees Cook
2020-06-29 15:50 ` Arvind Sankar
2020-06-29 15:51 ` Ard Biesheuvel
2020-06-29 16:10 ` Kees Cook
2020-06-29 14:09 ` [PATCH v3 2/7] x86/boot/compressed: Force hidden visibility for all symbol references Arvind Sankar
2020-06-29 15:50 ` Kees Cook
2020-07-14 9:20 ` Sedat Dilek
2020-07-14 9:47 ` Ard Biesheuvel
2020-06-29 14:09 ` [PATCH v3 3/7] x86/boot/compressed: Get rid of GOT fixup code Arvind Sankar
2020-06-29 15:53 ` Kees Cook
2020-06-29 14:09 ` [PATCH v3 4/7] x86/boot: Add .text.* to setup.ld Arvind Sankar
2020-06-29 15:55 ` Kees Cook
2020-06-29 14:09 ` [PATCH v3 5/7] x86/boot: Remove run-time relocations from .head.text code Arvind Sankar
2020-06-29 16:04 ` Kees Cook
2020-06-29 17:01 ` Arvind Sankar
2020-07-14 13:20 ` Sedat Dilek
2020-06-29 14:09 ` [PATCH v3 6/7] x86/boot: Remove runtime relocations from head_{32,64}.S Arvind Sankar
2020-06-29 16:06 ` Kees Cook
2020-06-29 16:52 ` Arvind Sankar
2020-06-29 14:09 ` [PATCH v3 7/7] x86/boot: Check that there are no runtime relocations Arvind Sankar
2020-06-29 16:09 ` Kees Cook
2020-06-29 16:11 ` Ard Biesheuvel
2020-06-29 16:20 ` Kees Cook
2020-06-29 16:56 ` Arvind Sankar
2020-06-29 17:37 ` Fangrui Song
2020-06-29 18:11 ` Ard Biesheuvel
2020-06-29 23:34 ` Fangrui Song
2020-06-30 16:26 ` Ard Biesheuvel
2020-06-30 17:54 ` Arvind Sankar
2020-06-30 22:00 ` Fangrui Song
2020-06-30 23:27 ` Arvind Sankar
2020-07-01 6:44 ` Ard Biesheuvel
2020-07-01 14:42 ` Arvind Sankar
2020-06-29 18:43 ` Arvind Sankar
2020-07-14 2:38 ` [PATCH v4 0/7] x86/boot: Remove runtime relocations from compressed kernel Arvind Sankar
2020-07-14 13:15 ` Sedat Dilek
2020-07-14 14:15 ` Arvind Sankar
2020-07-14 18:13 ` Sedat Dilek
2020-07-14 18:30 ` Sedat Dilek
2020-07-14 18:33 ` Sedat Dilek
2020-07-14 19:21 ` Sedat Dilek
2020-07-14 19:29 ` Arvind Sankar
2020-07-14 19:53 ` Sedat Dilek
2020-07-14 20:07 ` Arvind Sankar
2020-07-14 20:10 ` Sedat Dilek
2020-07-14 20:14 ` Arvind Sankar
2020-07-14 20:17 ` Sedat Dilek
2020-07-14 20:08 ` Sedat Dilek
2020-07-14 20:21 ` Arvind Sankar
2020-07-14 20:24 ` Sedat Dilek
2020-07-14 20:27 ` Sedat Dilek
2020-07-14 20:35 ` Arvind Sankar
2020-07-14 20:43 ` Sedat Dilek
2020-07-14 21:07 ` Arvind Sankar
2020-07-14 20:33 ` Arvind Sankar
2020-07-15 0:41 ` [PATCH v5 0/7] x86/boot: Remove run-time " Arvind Sankar
2020-07-15 1:46 ` Sedat Dilek
2020-07-15 7:11 ` Sedat Dilek
2020-07-17 13:46 ` Arvind Sankar
2020-07-17 18:16 ` Nick Desaulniers
2020-07-17 18:21 ` Sedat Dilek
2020-07-17 20:17 ` [PATCH-next " Arvind Sankar
2020-07-17 23:46 ` Nick Desaulniers
2020-07-29 22:04 ` Kees Cook
2020-07-29 22:23 ` Arvind Sankar
2020-07-30 2:38 ` Kees Cook
2020-07-17 20:17 ` [PATCH-next v5 1/7] x86/boot/compressed: Move .got.plt entries out of the .got section Arvind Sankar
2020-07-17 20:17 ` [PATCH-next v5 2/7] x86/boot/compressed: Force hidden visibility for all symbol references Arvind Sankar
2020-07-17 20:17 ` [PATCH-next v5 3/7] x86/boot/compressed: Get rid of GOT fixup code Arvind Sankar
2020-07-17 20:17 ` [PATCH-next v5 4/7] x86/boot: Add .text.* to setup.ld Arvind Sankar
2020-07-17 20:17 ` [PATCH-next v5 5/7] x86/boot: Remove run-time relocations from .head.text code Arvind Sankar
2020-07-17 20:18 ` [PATCH-next v5 6/7] x86/boot: Remove run-time relocations from head_{32,64}.S Arvind Sankar
2020-07-17 20:18 ` [PATCH-next v5 7/7] x86/boot: Check that there are no run-time relocations Arvind Sankar
2020-07-18 5:44 ` [PATCH v5 0/7] x86/boot: Remove run-time relocations from compressed kernel Ard Biesheuvel
2020-07-18 7:01 ` Sedat Dilek
2020-07-24 23:25 ` Kees Cook
2020-07-31 14:53 ` Arvind Sankar
2020-07-31 14:58 ` Sedat Dilek
2020-07-31 20:27 ` [PATCH v6 " Arvind Sankar
2020-07-31 20:27 ` [PATCH v6 1/7] x86/boot/compressed: Move .got.plt entries out of the .got section Arvind Sankar
2020-07-31 20:27 ` [PATCH v6 2/7] x86/boot/compressed: Force hidden visibility for all symbol references Arvind Sankar
2020-07-31 20:27 ` [PATCH v6 3/7] x86/boot/compressed: Get rid of GOT fixup code Arvind Sankar
2020-07-31 20:27 ` [PATCH v6 4/7] x86/boot: Add .text.* to setup.ld Arvind Sankar
2020-07-31 20:27 ` [PATCH v6 5/7] x86/boot: Remove run-time relocations from .head.text code Arvind Sankar
2020-07-31 20:27 ` [PATCH v6 6/7] x86/boot: Remove run-time relocations from head_{32,64}.S Arvind Sankar
2020-07-31 20:27 ` [PATCH v6 7/7] x86/boot: Check that there are no run-time relocations Arvind Sankar
2020-07-31 23:15 ` [PATCH v6 0/7] x86/boot: Remove run-time relocations from compressed kernel Kees Cook
2020-07-15 0:41 ` [PATCH v5 1/7] x86/boot/compressed: Move .got.plt entries out of the .got section Arvind Sankar
2020-07-15 8:52 ` Sedat Dilek
2020-07-15 0:41 ` [PATCH v5 2/7] x86/boot/compressed: Force hidden visibility for all symbol references Arvind Sankar
2020-07-15 8:54 ` Sedat Dilek
2020-07-15 0:41 ` [PATCH v5 3/7] x86/boot/compressed: Get rid of GOT fixup code Arvind Sankar
2020-07-15 8:54 ` Sedat Dilek
2020-07-15 0:41 ` [PATCH v5 4/7] x86/boot: Add .text.* to setup.ld Arvind Sankar
2020-07-15 8:55 ` Sedat Dilek
2020-07-15 0:41 ` [PATCH v5 5/7] x86/boot: Remove run-time relocations from .head.text code Arvind Sankar
2020-07-15 8:56 ` Sedat Dilek
2020-07-15 0:41 ` [PATCH v5 6/7] x86/boot: Remove run-time relocations from head_{32,64}.S Arvind Sankar
2020-07-15 8:58 ` Sedat Dilek [this message]
2020-07-15 9:03 ` Ard Biesheuvel
2020-07-15 9:10 ` Sedat Dilek
2020-07-15 0:41 ` [PATCH v5 7/7] x86/boot: Check that there are no run-time relocations Arvind Sankar
2020-07-15 9:00 ` Sedat Dilek
2020-07-15 9:12 ` Sedat Dilek
2020-07-14 2:38 ` [PATCH v4 1/7] x86/boot/compressed: Move .got.plt entries out of the .got section Arvind Sankar
2020-07-14 2:38 ` [PATCH v4 2/7] x86/boot/compressed: Force hidden visibility for all symbol references Arvind Sankar
2020-07-14 2:38 ` [PATCH v4 3/7] x86/boot/compressed: Get rid of GOT fixup code Arvind Sankar
2020-07-14 2:38 ` [PATCH v4 4/7] x86/boot: Add .text.* to setup.ld Arvind Sankar
2020-07-14 2:38 ` [PATCH v4 5/7] x86/boot: Remove run-time relocations from .head.text code Arvind Sankar
2020-07-14 2:38 ` [PATCH v4 6/7] x86/boot: Remove runtime relocations from head_{32,64}.S Arvind Sankar
2020-07-14 2:38 ` [PATCH v4 7/7] x86/boot: Check that there are no runtime relocations Arvind Sankar
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