Messages in this thread | | | Date | Tue, 24 Nov 2020 13:24:42 +0000 | From | Marc Zyngier <> | Subject | Re: [RFC PATCH 3/6] kvm: arm64: Fix up RELR relocation in hyp code/data |
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On 2020-11-19 16:25, David Brazdil wrote: > The arm64 kernel also supports packing of relocation data using the > RELR > format. Implement a parser of RELR data and fixup the relocations using > the same infra as RELA relocs. > > Signed-off-by: David Brazdil <dbrazdil@google.com> > --- > arch/arm64/kvm/va_layout.c | 41 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 41 insertions(+) > > diff --git a/arch/arm64/kvm/va_layout.c b/arch/arm64/kvm/va_layout.c > index b80fab974896..7f45a98eacfd 100644 > --- a/arch/arm64/kvm/va_layout.c > +++ b/arch/arm64/kvm/va_layout.c > @@ -145,6 +145,43 @@ static void __fixup_hyp_rela(void) > __fixup_hyp_rel(rel[i].r_offset); > } > > +#ifdef CONFIG_RELR > +static void __fixup_hyp_relr(void) > +{ > + u64 *rel, *end; > + > + rel = (u64*)(kimage_vaddr + __load_elf_u64(__relr_offset)); > + end = rel + (__load_elf_u64(__relr_size) / sizeof(*rel)); > + > + while (rel < end) { > + unsigned n; > + u64 addr = *(rel++); > + > + /* Address must not have the LSB set. */ > + BUG_ON(addr & BIT(0)); > + > + /* Fix up the first address of the chain. */ > + __fixup_hyp_rel(addr); > + > + /* > + * Loop over bitmaps, i.e. as long as words' LSB is 1. > + * Each bit (ordered from LSB to MSB) represents one word from > + * the last full address (exclusive). If the corresponding bit > + * is 1, there is a relative relocation on that word. > + */
What is the endianness of this bitmap? Is it guaranteed to be in CPU-endian format?
> + for (n = 0; rel < end && (*rel & BIT(0)); n++) { > + unsigned i; > + u64 bitmap = *(rel++);
nit: if you change this u64 for an unsigned long...
> + > + for (i = 1; i < 64; ++i) { > + if ((bitmap & BIT(i))) > + __fixup_hyp_rel(addr + 8 * (63 * n + i)); > + }
... this can be written as:
i = 1; for_each_set_bit_from(i, &bitmap, 64) __fixup_hyp_rel(addr + 8 * (63 * n + i));
> + } > + } > +} > +#endif > + > /* > * The kernel relocated pointers to kernel VA. Iterate over > relocations in > * the hypervisor ELF sections and convert them to hyp VA. This avoids > the > @@ -156,6 +193,10 @@ __init void kvm_fixup_hyp_relocations(void) > return; > > __fixup_hyp_rela(); > + > +#ifdef CONFIG_RELR > + __fixup_hyp_relr(); > +#endif > } > > static u32 compute_instruction(int n, u32 rd, u32 rn)
Thanks,
M. -- Jazz is not dead. It just smells funny...
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