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authorBen Woodard <woodard@redhat.com>2022-01-24 10:46:18 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2022-02-01 14:49:46 -0300
commitce9a68c57c260c8417afc93972849ac9ad243ec4 (patch)
treeadedf6275c170675cdd751e0d59f569f4b3c69ca /NEWS
parent32612615c58b394c3eb09f020f31310797ad3854 (diff)
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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>
Diffstat (limited to 'NEWS')
-rw-r--r--NEWS4
1 files changed, 4 insertions, 0 deletions
diff --git a/NEWS b/NEWS
index 34151fb3f3..f26c3ba52f 100644
--- a/NEWS
+++ b/NEWS
@@ -172,6 +172,10 @@ Deprecated and removed features, and other changes affecting compatibility:
proper bind-now support. The loader now advertises via the la_symbind
flags that PLT trace is not possible.
+* The audit interface on aarch64 is extended to support both the indirect
+ result location register (x8) and NEON Q register. Old audit modules are
+ rejected by the loader.
+
Changes to build and runtime requirements:
[Add changes to build and runtime requirements here]