Hi Jun, On 02/07/18 12:16, Jun Yao wrote: > Add init_pg_dir to vmlinux.lds.S and boiler-plate > clearing/cleaning/invalidating it in head.S.
With just this patch I get a weird link error from ld[0]: aarch64-linux-gnu-ld:./arch/arm64/kernel/vmlinux.lds:90 cannot move location counter backwards (from ffff000008fa8000 to fffefffff8ead000) make[2]: *** [/home/morse/linux/Makefile:1015: vmlinux] Error 1 make[1]: *** [Makefile:146: sub-make] Error 2 make: *** [Makefile:24: __sub-make] Error 2 Where line 90 is your INIT_DIR macro. I'm going to guess that this is because SWAPPER_DIR_SIZE is defined in terms of '_end', and that this can't be used inside '.init.data'. Moving it outside the '.init.data' section fixes this [1]. We only need this to be within the __init_begin/__init_end markers that free_initmem() uses, which it still is after this change. A side effect of this is we shouldn't label the C externs '__initdata' as they are no longer in the '.init.data' section. (looks like I was wrong about sparse being able to pick that up...) (Could we make it clearer INIT_DIR is related to the page tables, e.g. INIT_PG_TABLES? INIT_DIR makes me think of the rootfs for some reason) Otherwise some boring nits: > diff --git a/arch/arm64/include/asm/assembler.h > b/arch/arm64/include/asm/assembler.h > index 0bcc98dbba56..414fb167e3e7 100644 > --- a/arch/arm64/include/asm/assembler.h > +++ b/arch/arm64/include/asm/assembler.h > @@ -456,6 +456,29 @@ USER(\label, ic ivau, \tmp2) // > invalidate I line PoU > b.ne 9998b > .endm > > +/* > + * clear_page - clear one page > + */ > + .macro clear_page, start:req > +9996: stp xzr, xzr, [\start], #16 > + stp xzr, xzr, [\start], #16 > + stp xzr, xzr, [\start], #16 > + stp xzr, xzr, [\start], #16 > + tst \start, #(PAGE_SIZE - 1) (This will match any page-aligned end address, so this macro only clears one page if you give it a page aligned start address. Just something for us to remember.) > + b.ne 9996b > + .endm The rest of this file uses the white-space $instruction[tab]$arg, $arg, here you mix and match. > +/* > + * clear_pages - clear contiguous pages > + */ > + .macro clear_pages, start:req, count:req > +9997: cbz \count, 9998f > + clear_page \start > + sub \count, \count, #1 > + b 9997b > +9998: > + .endm Both callers of this have a start/end address, you may as well move the 'count' calculation in here to save duplicating it. With the link-error fixed: Reviewed-by: James Morse <[email protected]> Thanks, James > diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S > index 605d1b60469c..d4fc68286a49 100644 > --- a/arch/arm64/kernel/vmlinux.lds.S > +++ b/arch/arm64/kernel/vmlinux.lds.S > @@ -68,6 +68,12 @@ jiffies = jiffies_64; > #define TRAMP_TEXT > #endif > > +#define INIT_DIR \ > + . = ALIGN(PAGE_SIZE); \ > + init_pg_dir = .; \ > + . += SWAPPER_DIR_SIZE; \ > + init_pg_end = .; > + > /* > * The size of the PE/COFF section that covers the kernel image, which > * runs from stext to _edata, must be a round multiple of the PE/COFF > @@ -168,6 +174,7 @@ SECTIONS > CON_INITCALL > SECURITY_INITCALL > INIT_RAM_FS > + INIT_DIR > *(.init.rodata.* .init.bss) /* from the EFI stub */ > } > .exit.data : { > [0] aarch64-linux-gnu-ld --version GNU ld (GNU Binutils for Debian) 2.30.90.20180627 Copyright (C) 2018 Free Software Foundation, Inc. This program is free software; you may redistribute it under the terms of the GNU General Public License version 3 or (at your option) a later version. This program has absolutely no warranty. [1] Move INIT_DIR outside the .init.data section diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index d4fc68286a49..169abc3d01c8 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -167,6 +167,8 @@ SECTIONS __inittext_end = .; __initdata_begin = .; + INIT_DIR + .init.data : { INIT_DATA INIT_SETUP(16) @@ -174,7 +176,6 @@ SECTIONS CON_INITCALL SECURITY_INITCALL INIT_RAM_FS - INIT_DIR *(.init.rodata.* .init.bss) /* from the EFI stub */ } .exit.data : {
