glibc/sysdeps/aarch64/dl-link.sym
Ben Woodard b118bce87a elf: Fix runtime linker auditing on aarch64 (BZ #26643)
The rtld audit support show two problems on aarch64:

  1. _dl_runtime_resolve does not preserve x8, the indirect result
      location register, which might generate wrong result calls
      depending of the function signature.

  2. The NEON Q registers pushed onto the stack by _dl_runtime_resolve
     were twice the size of D registers extracted from the stack frame by
     _dl_runtime_profile.

While 2. might result in wrong information passed on the PLT tracing,
1. generates wrong runtime behaviour.

The aarch64 rtld audit support is changed to:

  * Both La_aarch64_regs and La_aarch64_retval are expanded to include
    both x8 and the full sized NEON V registers, as defined by the
    ABI.

  * dl_runtime_profile needed to extract registers saved by
    _dl_runtime_resolve and put them into the new correctly sized
    La_aarch64_regs structure.

  * The LAV_CURRENT check is change to only accept new audit modules
    to avoid the undefined behavior of not save/restore x8.

  * Different than other architectures, audit modules older than
    LAV_CURRENT are rejected (both La_aarch64_regs and La_aarch64_retval
    changed their layout and there are no requirements to support multiple
    audit interface with the inherent aarch64 issues).

  * A new field is also reserved on both La_aarch64_regs and
    La_aarch64_retval to support variant pcs symbols.

Similar to x86, a new La_aarch64_vector type to represent the NEON
register is added on the La_aarch64_regs (so each type can be accessed
directly).

Since LAV_CURRENT was already bumped to support bind-now, there is
no need to increase it again.

Checked on aarch64-linux-gnu.

Co-authored-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
(cherry picked from commit ce9a68c57c)

Resolved conflicts:
	NEWS
	elf/rtld.c
2022-04-12 13:33:10 -04:00

18 lines
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Plaintext

#include <stddef.h>
#include <sysdep.h>
#include <link.h>
#include <dl-tlsdesc.h>
DL_SIZEOF_RG sizeof(struct La_aarch64_regs)
DL_SIZEOF_RV sizeof(struct La_aarch64_retval)
DL_OFFSET_RG_X0 offsetof(struct La_aarch64_regs, lr_xreg)
DL_OFFSET_RG_V0 offsetof(struct La_aarch64_regs, lr_vreg)
DL_OFFSET_RG_SP offsetof(struct La_aarch64_regs, lr_sp)
DL_OFFSET_RG_LR offsetof(struct La_aarch64_regs, lr_lr)
DL_OFFSET_RG_VPCS offsetof(struct La_aarch64_regs, lr_vpcs)
DL_OFFSET_RV_X0 offsetof(struct La_aarch64_retval, lrv_xreg)
DL_OFFSET_RV_V0 offsetof(struct La_aarch64_retval, lrv_vreg)
DL_OFFSET_RV_VPCS offsetof(struct La_aarch64_retval, lrv_vpcs)