[PATCH] arm64/kexec-arm64: add support for R_AARCH64_LDST128_ABS_LO12_NC rela

[Pingfan Liu]

I find that kexec-tools can not work with clang either, compose a
series ([PATCH 0/3] arm64: add support for new reloc type in
kexec-arm64.c) to fix these relocs issues.

So please ignore this thread.

Thanks,
Pingfan

On Thu, Mar 31, 2022 at 9:22 AM Pingfan Liu <piliu at redhat.com> wrote:
>
> Sorry for forgetting to add the address of the mailing list.
>
> On Thu, Mar 31, 2022 at 9:18 AM Pingfan Liu <piliu at redhat.com> wrote:
> >
> > GCC 12 has some changes, which affects the generated AArch64 code of kexec-tools.
> > Accordingly, a new rel type R_AARCH64_LDST128_ABS_LO12_NC is confronted
> > by machine_apply_elf_rel() on AArch64. This fails the load of kernel
> > with the message "machine_apply_elf_rel: ERROR Unknown type: 299"
> >
> > Citing from objdump -rDSl purgatory/purgatory.ro
> >
> > 0000000000000f80 <sha256_starts>:
> > sha256_starts():
> >      f80:       90000001        adrp    x1, 0 <verify_sha256_digest>
> >                         f80: R_AARCH64_ADR_PREL_PG_HI21 .text+0xfa0
> >      f84:       a9007c1f        stp     xzr, xzr, [x0]
> >      f88:       3dc00021        ldr     q1, [x1]
> >                         f88: R_AARCH64_LDST128_ABS_LO12_NC      .text+0xfa0
> >      f8c:       90000001        adrp    x1, 0 <verify_sha256_digest>
> >                         f8c: R_AARCH64_ADR_PREL_PG_HI21 .text+0xfb0
> >      f90:       3dc00020        ldr     q0, [x1]
> >                         f90: R_AARCH64_LDST128_ABS_LO12_NC      .text+0xfb0
> >      f94:       ad008001        stp     q1, q0, [x0, #16]
> >      f98:       d65f03c0        ret
> >      f9c:       d503201f        nop
> >      fa0:       6a09e667        .inst   0x6a09e667 ; undefined
> >      fa4:       bb67ae85        .inst   0xbb67ae85 ; undefined
> >      fa8:       3c6ef372        .inst   0x3c6ef372 ; undefined
> >      fac:       a54ff53a        ld3w    {z26.s-z28.s}, p5/z, [x9, #-3, mul vl]
> >      fb0:       510e527f        sub     wsp, w19, #0x394
> >      fb4:       9b05688c        madd    x12, x4, x5, x26
> >      fb8:       1f83d9ab        .inst   0x1f83d9ab ; undefined
> >      fbc:       5be0cd19        .inst   0x5be0cd19 ; undefined
> >
> > Here, gcc generates codes, which make loads and stores carried out using
> > the 128-bits floating-point registers. And a new rel type
> > R_AARCH64_LDST128_ABS_LO12_NC should be handled.
> >
> > Make machine_apply_elf_rel() coped with this new reloc, so kexec-tools
> > can work smoothly.
> >
> > Signed-off-by: Pingfan Liu <piliu at redhat.com>
> > Cc: Geoff Levand <geoff at infradead.org>
> > Cc: Catalin Marinas <catalin.marinas at arm.com>
> > Cc: Simon Horman <horms at verge.net.au>
> > ---
> >  kexec/arch/arm64/kexec-arm64.c | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> >
> > diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
> > index 9dd072c..e25f600 100644
> > --- a/kexec/arch/arm64/kexec-arm64.c
> > +++ b/kexec/arch/arm64/kexec-arm64.c
> > @@ -1248,6 +1248,10 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr, struct mem_sym *UNUSED(sym),
> >
> >  #if !defined(R_AARCH64_LDST64_ABS_LO12_NC)
> >  # define R_AARCH64_LDST64_ABS_LO12_NC 286
> > +#endif
> > +
> > +#if !defined(R_AARCH64_LDST128_ABS_LO12_NC)
> > +# define R_AARCH64_LDST128_ABS_LO12_NC 299
> >  #endif
> >
> >         uint64_t *loc64;
> > @@ -1309,6 +1313,7 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr, struct mem_sym *UNUSED(sym),
> >                 *loc32 = cpu_to_le32(le32_to_cpu(*loc32)
> >                         + (((value - address) >> 2) & 0x3ffffff));
> >                 break;
> > +       /* encode imm field with bits [11:3] of value */
> >         case R_AARCH64_LDST64_ABS_LO12_NC:
> >                 if (value & 7)
> >                         die("%s: ERROR Unaligned value: %lx\n", __func__,
> > @@ -1318,6 +1323,17 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr, struct mem_sym *UNUSED(sym),
> >                 *loc32 = cpu_to_le32(le32_to_cpu(*loc32)
> >                         + ((value & 0xff8) << (10 - 3)));
> >                 break;
> > +
> > +       /* encode imm field with bits [11:4] of value */
> > +       case R_AARCH64_LDST128_ABS_LO12_NC:
> > +               if (value & 15)
> > +                       die("%s: ERROR Unaligned value: %lx\n", __func__,
> > +                               value);
> > +               type = "LDST128_ABS_LO12_NC";
> > +               loc32 = ptr;
> > +               imm = value & 0xff0;
> > +               *loc32 = cpu_to_le32(le32_to_cpu(*loc32) + (imm << (10 - 4)));
> > +               break;
> >         default:
> >                 die("%s: ERROR Unknown type: %lu\n", __func__, r_type);
> >                 break;
> > --
> > 2.31.1
> >