Messages in this thread | | | Date | Wed, 19 May 2021 21:55:40 -0700 | From | Drew Fustini <> | Subject | Re: [PATCH] riscv: mm: Fix W+X mappings at boot |
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On Sun, May 16, 2021 at 05:00:38PM +0800, Jisheng Zhang wrote: > From: Jisheng Zhang <jszhang@kernel.org> > > When the kernel mapping was moved the last 2GB of the address space, > (__va(PFN_PHYS(max_low_pfn))) is much smaller than the .data section > start address, the last set_memory_nx() in protect_kernel_text_data() > will fail, thus the .data section is still mapped as W+X. This results > in below W+X mapping waring at boot. Fix it by passing the correct > .data section page num to the set_memory_nx(). > > [ 0.396516] ------------[ cut here ]------------ > [ 0.396889] riscv/mm: Found insecure W+X mapping at address (____ptrval____)/0xffffffff80c00000 > [ 0.398347] WARNING: CPU: 0 PID: 1 at arch/riscv/mm/ptdump.c:258 note_page+0x244/0x24a > [ 0.398964] Modules linked in: > [ 0.399459] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc1+ #14 > [ 0.400003] Hardware name: riscv-virtio,qemu (DT) > [ 0.400591] epc : note_page+0x244/0x24a > [ 0.401368] ra : note_page+0x244/0x24a > [ 0.401772] epc : ffffffff80007c86 ra : ffffffff80007c86 sp : ffffffe000e7bc30 > [ 0.402304] gp : ffffffff80caae88 tp : ffffffe000e70000 t0 : ffffffff80cb80cf > [ 0.402800] t1 : ffffffff80cb80c0 t2 : 0000000000000000 s0 : ffffffe000e7bc80 > [ 0.403310] s1 : ffffffe000e7bde8 a0 : 0000000000000053 a1 : ffffffff80c83ff0 > [ 0.403805] a2 : 0000000000000010 a3 : 0000000000000000 a4 : 6c7e7a5137233100 > [ 0.404298] a5 : 6c7e7a5137233100 a6 : 0000000000000030 a7 : ffffffffffffffff > [ 0.404849] s2 : ffffffff80e00000 s3 : 0000000040000000 s4 : 0000000000000000 > [ 0.405393] s5 : 0000000000000000 s6 : 0000000000000003 s7 : ffffffe000e7bd48 > [ 0.405935] s8 : ffffffff81000000 s9 : ffffffffc0000000 s10: ffffffe000e7bd48 > [ 0.406476] s11: 0000000000001000 t3 : 0000000000000072 t4 : ffffffffffffffff > [ 0.407016] t5 : 0000000000000002 t6 : ffffffe000e7b978 > [ 0.407435] status: 0000000000000120 badaddr: 0000000000000000 cause: 0000000000000003 > [ 0.408052] Call Trace: > [ 0.408343] [<ffffffff80007c86>] note_page+0x244/0x24a > [ 0.408855] [<ffffffff8010c5a6>] ptdump_hole+0x14/0x1e > [ 0.409263] [<ffffffff800f65c6>] walk_pgd_range+0x2a0/0x376 > [ 0.409690] [<ffffffff800f6828>] walk_page_range_novma+0x4e/0x6e > [ 0.410146] [<ffffffff8010c5f8>] ptdump_walk_pgd+0x48/0x78 > [ 0.410570] [<ffffffff80007d66>] ptdump_check_wx+0xb4/0xf8 > [ 0.410990] [<ffffffff80006738>] mark_rodata_ro+0x26/0x2e > [ 0.411407] [<ffffffff8031961e>] kernel_init+0x44/0x108 > [ 0.411814] [<ffffffff80002312>] ret_from_exception+0x0/0xc > [ 0.412309] ---[ end trace 7ec3459f2547ea83 ]--- > [ 0.413141] Checked W+X mappings: failed, 512 W+X pages found > > Fixes: 2bfc6cd81bd17e43 ("riscv: Move kernel mapping outside of linear mapping") > Signed-off-by: Jisheng Zhang <jszhang@kernel.org> > --- > arch/riscv/mm/init.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index 4faf8bd157ea..4c4c92ce0bb8 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -746,14 +746,18 @@ void __init protect_kernel_text_data(void) > unsigned long init_data_start = (unsigned long)__init_data_begin; > unsigned long rodata_start = (unsigned long)__start_rodata; > unsigned long data_start = (unsigned long)_data; > - unsigned long max_low = (unsigned long)(__va(PFN_PHYS(max_low_pfn))); > +#if defined(CONFIG_64BIT) && defined(CONFIG_MMU) > + unsigned long end_va = kernel_virt_addr + load_sz; > +#else > + unsigned long end_va = (unsigned long)(__va(PFN_PHYS(max_low_pfn))); > +#endif > > set_memory_ro(text_start, (init_text_start - text_start) >> PAGE_SHIFT); > set_memory_ro(init_text_start, (init_data_start - init_text_start) >> PAGE_SHIFT); > set_memory_nx(init_data_start, (rodata_start - init_data_start) >> PAGE_SHIFT); > /* rodata section is marked readonly in mark_rodata_ro */ > set_memory_nx(rodata_start, (data_start - rodata_start) >> PAGE_SHIFT); > - set_memory_nx(data_start, (max_low - data_start) >> PAGE_SHIFT); > + set_memory_nx(data_start, (end_va - data_start) >> PAGE_SHIFT); > } > > void mark_rodata_ro(void) > -- > 2.31.0 > > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv
I know there is a new thread now with a different approach but I wanted to say that this did fix that warning on the BeagleV Starlight beta prototype board [1] with the StarFive JH7100 SoC [2]. I am using Emil's starlight branch [3] which is a set of StarFive patches on top of 5.13-rc2. Emil included this W+X mapping patch [4]. It does fix the warning on boot for me and the bootlog [5] shows:
[ 2.302598] Checked W+X mappings: passed, no W+X pages found
Thus if useful, here is my TB:
Tested-by: Drew Fustini <drew@beagleboard.org>
thanks, drew
[1] https://github.com/beagleboard/beaglev-starlight [2] https://github.com/starfive-tech/beaglev_doc [3] https://github.com/esmil/linux/tree/starlight [4] https://github.com/esmil/linux/commit/b865eb820db8b9b94a7a2d2619e46cc3251fb90d [5] https://gist.github.com/pdp7/0bf9088d034384d29ba4e8418c9dfd91
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