Change Details

Fix default image base and max page size. Support more relocation types. Support secure PLT (see below). musl supports only secure PLT PowerPC psABI specified an old-style .plt (BSS PLT) (.plt is NOBITS and written by the dynamic loader) that is both writable and executable. Linkers don't make separate RW- and RWE segments, which causes all initially writable memory (think .data) executable. This is a big security concern so a new PLT scheme (secure PLT) was developed to address the security issue. This helps PR40888. Actually, with this patch, I think many -shared/-static/-pie applications linked against musl will work. A hello world program linked against glibc doesn't run. TLS is not implemented but I believe PPC.cpp can just reuse TLS code from PPC64.cpp. I create ppc32-* instead of ppc-* for tests as I plan to use ppc-* for tests shareable on ppc32 and ppc64.

* Fix default image base and max page size. * Support more relocation types. * Support secure PLT (see below). musl supports only secure PLT * Support .got2 for position independent code * Add a new thunk: PPC32PltCallStub. Similar to PPC64PltCallStub, it is used by R_PPC_REL24 and R_PPC_PLTREL24. On ppc32, a PLT stub used in -pie/-shared loads an address relative to .got2+0x8000. Two object files have 2 .got2 with different addresses. Thus a PLT stub can't be shared by two object files. To handle this incompatibility, make Thunk::isCompatibleWith accept another parameter `const InputSection &`. PowerPC psABI specified an old-style .plt (BSS PLT) (.plt is NOBITS and written by the dynamic loader) that is both writable and executable. Linkers don't make separate RW- and RWE segments, which causes all initially writable memory (think .data) executable. This is a big security concern so a new PLT scheme (secure PLT) was developed to address the security issue. This helps PR40888. Actually, with this patch, I think many -shared/-static/-pie applications linked against musl will work. A hello world program linked against glibc doesn't run. TLS is not implemented but I believe PPC.cpp can just reuse TLS code from PPC64.cpp. I create ppc32-* instead of ppc-* for tests as I plan to use ppc-* for tests shareable on ppc32 and ppc64.

* Fix default image base and max page size. * Support more relocation types. * Support secure PLT (see below). musl supports only secure PLT * Support .got2 for position independent code * Add a new thunk: PPC32PltCallStub. Similar to PPC64PltCallStub, it is used by R_PPC_REL24 and R_PPC_PLTREL24. On ppc32, a PLT stub used in -pie/-shared loads an address relative to .got2+0x8000. Two object files have 2 .got2 with different addresses. Thus a PLT stub can't be shared by two object files. To handle this incompatibility, make Thunk::isCompatibleWith accept another parameter `const InputSection &`. PowerPC psABI specified an old-style .plt (BSS PLT) (.plt is NOBITS and written by the dynamic loader) that is both writable and executable. Linkers don't make separate RW- and RWE segments, which causes all initially writable memory (think .data) executable. This is a big security concern so a new PLT scheme (secure PLT) was developed to address the security issue. This helps PR40888. Actually, with this patch, I think many -shared/-static/-pie applications linked against musl will work. A hello world program linked against glibc doesn't run. TLS is not implemented but I believe PPC.cpp can just reuse TLS code from PPC64.cpp. I create ppc32-* instead of ppc-* for tests as I plan to use ppc-* for tests shareable on ppc32 and ppc64.