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authorStefan Liebler <stli@linux.vnet.ibm.com>2016-03-31 17:37:16 +0200
committerStefan Liebler <stli@linux.vnet.ibm.com>2016-03-31 17:37:16 +0200
commit4603c51ef7989d7eb800cdd6f42aab206f891077 (patch)
treec15dc0e82a1b8b16eac6fdef4fef8c70450921eb /manual
parente91bd7465816f474617dcb4bbfe72f3594c5783c (diff)
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S390: Save and restore fprs/vrs while resolving symbols.
On s390, no fpr/vrs were saved while resolving a symbol via _dl_runtime_resolve/_dl_runtime_profile. According to the abi, the fpr-arguments are defined as call clobbered. In leaf-functions, gcc 4.9 and newer can use fprs for saving/restoring gprs instead of saving them to the stack. If gcc do this in one of the resolver-functions, then the floating point arguments of a library-function are invalid for the first library-function-call. Thus, this patch saves/restores the fprs around the resolving code. The same could occur for vector registers. Furthermore an ifunc-resolver could also clobber the vector/floating point argument registers. Thus this patch provides the further variants _dl_runtime_resolve_vx/ _dl_runtime_profile_vx, which are used if the kernel claims, that we run on a machine with vector registers. Furthermore, if _dl_runtime_profile calls _dl_call_pltexit, the pointers to inregs-/outregs-structs were setup invalid. Now they point to the correct location in the stack-frame. Before branching back to the caller, the return values are now restored instead of containing the return values of the _dl_call_pltexit() call. On s390-32, an endless loop occurs if _dl_call_pltexit() should be called. Now, this code-path branches to this function instead of just after the preceding basr-instruction. ChangeLog: * sysdeps/s390/s390-32/dl-trampoline.S: Include dl-trampoline.h twice to create a non-vector/vector version for _dl_runtime_resolve and _dl_runtime_profile. Move implementation to ... * sysdeps/s390/s390-32/dl-trampoline.h: ... here. (_dl_runtime_resolve) Save and restore fpr/vrs. (_dl_runtime_profile) Save and restore vrs and fix some issues if _dl_call_pltexit is called. * sysdeps/s390/s390-32/dl-machine.h (elf_machine_runtime_setup): Choose the correct resolver function if running on a machine with vx. * sysdeps/s390/s390-64/dl-trampoline.S: Include dl-trampoline.h twice to create a non-vector/vector version for _dl_runtime_resolve and _dl_runtime_profile. Move implementation to ... * sysdeps/s390/s390-64/dl-trampoline.h: ... here. (_dl_runtime_resolve) Save and restore fpr/vrs. (_dl_runtime_profile) Save and restore vrs and fix some issues * sysdeps/s390/s390-64/dl-machine.h: (elf_machine_runtime_setup): Choose the correct resolver function if running on a machine with vx.
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