| Message ID | 20201119162543.78001-4-dbrazdil@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kvm: arm64: Fix up hyp relocations | expand |
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.
On Thu, 19 Nov 2020 at 17:25, David Brazdil <dbrazdil@google.com> 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 Please prefer IS_ENABLED() [below] if the code in question can compile (but perhaps not link) correctly when the symbol is not set. > +static void __fixup_hyp_relr(void) __init ? > +{ > + u64 *rel, *end; > + > + rel = (u64*)(kimage_vaddr + __load_elf_u64(__relr_offset)); > + end = rel + (__load_elf_u64(__relr_size) / sizeof(*rel)); > + The reason for this little dance with the offset and size exists because the initial relocation routine runs from the ID mapping, but the relocation fixups are performed via the kernel's VA mapping, as the ID mapping does not cover the entire image. So simple adrp/add pairs aren't suitable there. In this case (as well as in the previous patch, btw), that problem does not exist, and so I think we should be able to simply define start and end markers inside the .rela sections, and reference them here as symbols with external linkage (which ensures that they are referenced relatively, although you could add in a __attribute__((visibility("hidden"))) for good measure) > + while (rel < end) { > + unsigned n; > + u64 addr = *(rel++); Parens are redundant here (and below) > + > + /* 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. > + */ > + for (n = 0; rel < end && (*rel & BIT(0)); n++) { > + unsigned i; > + u64 bitmap = *(rel++); > + > + for (i = 1; i < 64; ++i) { > + if ((bitmap & BIT(i))) > + __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) > -- > 2.29.2.299.gdc1121823c-goog >
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. + */ + for (n = 0; rel < end && (*rel & BIT(0)); n++) { + unsigned i; + u64 bitmap = *(rel++); + + for (i = 1; i < 64; ++i) { + if ((bitmap & BIT(i))) + __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)
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(+)