On Thu, Dec 17, 2020 at 12:33 AM Atish Patra <[email protected]> wrote: > > On Wed, Dec 16, 2020 at 10:51 PM Palmer Dabbelt <[email protected]> wrote: > > > > On Tue, 15 Dec 2020 22:02:54 PST (-0800), Palmer Dabbelt wrote: > > > On Wed, 04 Nov 2020 16:04:37 PST (-0800), Atish Patra wrote: > > >> In order to improve kernel text protection, we need separate .init.text/ > > >> .init.data/.text in separate sections. However, RISC-V linker relaxation > > >> code is not aware of any alignment between sections. As a result, it may > > >> relax any RISCV_CALL relocations between sections to JAL without > > >> realizing > > >> that an inter section alignment may move the address farther. That may > > >> lead to a relocation truncated fit error. However, linker relaxation code > > >> is aware of the individual section alignments. > > >> > > >> The detailed discussion on this issue can be found here. > > >> https://github.com/riscv/riscv-gnu-toolchain/issues/738 > > >> > > >> Keep the .init.text section aligned so that linker relaxation will take > > >> that as a hint while relaxing inter section calls. > > >> Here are the code size changes for each section because of this change. > > >> > > >> section change in size (in bytes) > > >> .head.text +4 > > >> .text +40 > > >> .init.text +6530 > > >> .exit.text +84 > > >> > > >> The only significant increase in size happened for .init.text because > > >> all intra relocations also use 2MB alignment. > > >> > > >> Suggested-by: Jim Wilson <[email protected]> > > >> Signed-off-by: Atish Patra <[email protected]> > > >> --- > > >> arch/riscv/kernel/vmlinux.lds.S | 8 +++++++- > > >> 1 file changed, 7 insertions(+), 1 deletion(-) > > >> > > >> diff --git a/arch/riscv/kernel/vmlinux.lds.S > > >> b/arch/riscv/kernel/vmlinux.lds.S > > >> index 3ffbd6cbdb86..cacd7898ba7f 100644 > > >> --- a/arch/riscv/kernel/vmlinux.lds.S > > >> +++ b/arch/riscv/kernel/vmlinux.lds.S > > >> @@ -30,7 +30,13 @@ SECTIONS > > >> . = ALIGN(PAGE_SIZE); > > >> > > >> __init_begin = .; > > >> - INIT_TEXT_SECTION(PAGE_SIZE) > > >> + __init_text_begin = .; > > >> + .init.text : AT(ADDR(.init.text) - LOAD_OFFSET) > > >> ALIGN(SECTION_ALIGN) { \ > > >> + _sinittext = .; \ > > >> + INIT_TEXT \ > > >> + _einittext = .; \ > > >> + } > > >> + > > >> . = ALIGN(8); > > >> __soc_early_init_table : { > > >> __soc_early_init_table_start = .; > > > > > > Not sure what's going on here (or why I wasn't catching it earlier), but > > > this > > > is breaking boot on one of my test configs. I'm not getting any Linux > > > boot > > > spew, so it's something fairly early. I'm running defconfig with > > > > > > CONFIG_PREEMPT=y > > > CONFIG_DEBUG_PREEMPT=y > > > CONFIG_PROVE_LOCKING=y > > > > > > It looks like that's been throwing a bunch of warnings for a while, but > > > it did > > > at least used to boot. No idea what PREEMPT would have to do with this, > > > and > > > the other two don't generally trigger issues that early in boot (or at > > > least, > > > trigger halts that early in boot). > > >
I am able to reproduce this issue but with CONFIG_PROVE_LOCKING not CONFIG_PREEMPT. With CONFIG_PREEMPT, I see a bunch of warnings around smp_processor_id but it boots even with 5.0. If CONFIG_PROVE_LOCKING is enabled, I am not able to boot using 5.0. However, 5.2.0 works fine. I am going to take a look at the issue with 5.0 and PROVE_LOCKING. The config preempt warnings are resolved by the following patch. I have tested it in Qemu. https://patchwork.kernel.org/project/linux-riscv/patch/[email protected]/ > > > There's a bunch of other stuff that depends on this that's on for-next so > > > I > > > don't want to just drop it, but I also don't want to break something. > > > I'm just > > > running QEMU's virt board. > > > > > I just verified for-next on QEMU 5.2.0 for virt (RV32,64, nommu) and > sifive_u as well. > I will give it a try on unleashed tomorrow as well with the above > configs enabled. > > > > I'll take a look again tomorrow night, but if anyone has some time to look > > > that'd be great! > > > > Looks like this breaks on QEMU 5.0.0 but works on 5.2.0. > > I will take a look tomorrow to check the root cause. > > I guess technically > > that means could be considered a regression, but as we don't really have any > > scheme for which old versions of QEMU we support it's not absolute. I'd > > usually err on the side of keeping support for older platforms, but in this > > case it's probably just not worth the time so I'm going to just ignore it. > > > > _______________________________________________ > > linux-riscv mailing list > > [email protected] > > http://lists.infradead.org/mailman/listinfo/linux-riscv > > > > -- > Regards, > Atish -- Regards, Atish
