From mboxrd@z Thu Jan 1 00:00:00 1970 From: ard.biesheuvel@linaro.org (Ard Biesheuvel) Date: Wed, 4 Oct 2017 13:20:26 +0100 Subject: [PATCH] ARM: compressed: discard ksym/kcrctab input section In-Reply-To: <87d163kt0m.fsf@free-electrons.com> References: <20170908153143.27279-1-ard.biesheuvel@linaro.org> <87d163kt0m.fsf@free-electrons.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 4 October 2017 at 13:16, Gregory CLEMENT wrote: > Hi Ard, > > On ven., sept. 08 2017, Ard Biesheuvel wrote: > >> As it turns out, building the ARM kernel with EFI support pulls in >> a couple of sections that we don't really need in the decompressor. >> This is due to the fact the the UEFI stub uses sort() to sort the UEFI >> memory map, which is an exported symbol pulled in from lib/sort.c. >> >> Before commit e4bae4d0b5f3 ("arm/efi: Split zImage code and data into >> separate PE/COFF sections"), this resulted in the following layout >> for the decompressor ELF binary. >> >> [Nr] Name Type Addr Off Size ES Flg Lk Inf Al >> [ 0] NULL 00000000 000000 000000 00 0 0 0 >> [ 1] .text PROGBITS 00000000 010000 009b3c 00 AX 0 0 512 >> [ 2] .rodata PROGBITS 00009b3c 019b3c 001684 00 A 0 0 4 >> [ 3] __ksymtab_strings PROGBITS 0000b1c0 01b1c0 000005 00 A 0 0 1 >> [ 4] .data PROGBITS 0000b1c8 01b1c8 000020 00 WA 0 0 8 >> [ 5] ___ksymtab+sort PROGBITS 0000b1e8 01b1e8 000008 00 WA 0 0 4 >> [ 6] .piggydata PROGBITS 0000b1f0 01b1f0 77ac38 00 A 0 0 1 >> [ 7] .got.plt PROGBITS 00785e28 795e28 00000c 04 WA 0 0 4 >> [ 8] .got PROGBITS 00785e34 795e34 000028 00 WA 0 0 4 >> [ 9] .pad PROGBITS 00785e5c 795e5c 000004 00 WA 0 0 1 >> [10] .bss NOBITS 00785e60 795e60 00001c 00 WA 0 0 4 >> [11] .stack NOBITS 00785e80 795e60 001000 00 WA 0 0 1 >> >> Commit e4bae4d0b5f3 made some changes to the linker script to allow the >> UEFI firmware to map the decompressor with strict R-X/RW- permissions >> before invoking it. Unfortunately, this turns out to break the boot on >> some systems, because the linker now also moves the ksymtab/kcrctab >> sections around, resulting in .piggydata to appear misaligned. >> >> [Nr] Name Type Addr Off Size ES Flg Lk Inf Al >> [ 0] NULL 00000000 000000 000000 00 0 0 0 >> [ 1] .text PROGBITS 00000000 010000 00a93c 00 AX 0 0 4096 >> [ 2] .rodata PROGBITS 0000a93c 01a93c 001684 00 A 0 0 4 >> [ 3] __ksymtab_strings PROGBITS 0000bfc0 01bfc0 000005 00 A 0 0 1 >> [ 4] .piggydata PROGBITS 0000bfc5 01bfc5 77ac47 00 A 0 0 1 >> [ 5] .got.plt PROGBITS 00786c0c 796c0c 00000c 04 WA 0 0 4 >> [ 6] .got PROGBITS 00786c18 796c18 000028 00 WA 0 0 4 >> [ 7] .pad PROGBITS 00786c40 796c40 000008 00 WA 0 0 1 >> [ 8] .data PROGBITS 00787000 797000 000200 00 WA 0 0 4096 >> [ 9] ___ksymtab+sort PROGBITS 00787200 797200 000008 00 WA 0 0 4 >> [10] .bss NOBITS 00787208 797208 00001c 00 WA 0 0 4 >> [11] .stack NOBITS 00787228 797208 001000 00 WA 0 0 1 >> >> So let's align piggydata explicitly, and discard these sections from the >> binary. >> >> Cc: Russell King >> Fixes: e4bae4d0b5f3 ("arm/efi: Split zImage code and data into separate ...") >> Tested-by: Gregory CLEMENT >> Signed-off-by: Ard Biesheuvel > > Any new for this patch? > > It is not yet in v4.14-rc whereas "arm/efi: Split zImage code and data > into separate ..." was already merged. So currently I have many boards > which still does not boot in v4.14-rc3. > Russell, any objections? >> --- >> arch/arm/boot/compressed/piggy.S | 1 + >> arch/arm/boot/compressed/vmlinux.lds.S | 1 + >> 2 files changed, 2 insertions(+) >> >> diff --git a/arch/arm/boot/compressed/piggy.S b/arch/arm/boot/compressed/piggy.S >> index f72088495f43..5d52c556dd32 100644 >> --- a/arch/arm/boot/compressed/piggy.S >> +++ b/arch/arm/boot/compressed/piggy.S >> @@ -1,5 +1,6 @@ >> .section .piggydata,#alloc >> .globl input_data >> + .align 2 >> input_data: >> .incbin "arch/arm/boot/compressed/piggy_data" >> .globl input_data_end >> diff --git a/arch/arm/boot/compressed/vmlinux.lds.S b/arch/arm/boot/compressed/vmlinux.lds.S >> index 7a4c59154361..5c5265be4605 100644 >> --- a/arch/arm/boot/compressed/vmlinux.lds.S >> +++ b/arch/arm/boot/compressed/vmlinux.lds.S >> @@ -29,6 +29,7 @@ SECTIONS >> * of the text/got segments. >> */ >> *(.data) >> + *(*ksymtab* *kcrctab*) >> } >> >> . = TEXT_START; >> -- >> 2.11.0 >> > > -- > Gregory Clement, Free Electrons > Kernel, drivers, real-time and embedded Linux > development, consulting, training and support. > http://free-electrons.com