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| author | H.J. Lu <hjl.tools@gmail.com> | 2024-01-04 20:19:39 -0800 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2024-01-05 05:49:49 -0800 |
| commit | 848746e88ec2aa22e8dea25f2110e2b2c59c712e (patch) | |
| tree | 33db2fa3d1b4dc68fec06609cb6bacc4d680a38e /sysdeps/x86_64/Makefile | |
| parent | 520b1df08de68a3de328b65a25b86300a7ddf512 (diff) | |
| download | glibc-848746e88ec2aa22e8dea25f2110e2b2c59c712e.tar.gz glibc-848746e88ec2aa22e8dea25f2110e2b2c59c712e.tar.xz glibc-848746e88ec2aa22e8dea25f2110e2b2c59c712e.zip | |
elf: Add ELF_DYNAMIC_AFTER_RELOC to rewrite PLT
Add ELF_DYNAMIC_AFTER_RELOC to allow target specific processing after relocation. For x86-64, add #define DT_X86_64_PLT (DT_LOPROC + 0) #define DT_X86_64_PLTSZ (DT_LOPROC + 1) #define DT_X86_64_PLTENT (DT_LOPROC + 3) 1. DT_X86_64_PLT: The address of the procedure linkage table. 2. DT_X86_64_PLTSZ: The total size, in bytes, of the procedure linkage table. 3. DT_X86_64_PLTENT: The size, in bytes, of a procedure linkage table entry. With the r_addend field of the R_X86_64_JUMP_SLOT relocation set to the memory offset of the indirect branch instruction. Define ELF_DYNAMIC_AFTER_RELOC for x86-64 to rewrite the PLT section with direct branch after relocation when the lazy binding is disabled. PLT rewrite is disabled by default since SELinux may disallow modifying code pages and ld.so can't detect it in all cases. Use $ export GLIBC_TUNABLES=glibc.cpu.plt_rewrite=1 to enable PLT rewrite with 32-bit direct jump at run-time or $ export GLIBC_TUNABLES=glibc.cpu.plt_rewrite=2 to enable PLT rewrite with 32-bit direct jump and on APX processors with 64-bit absolute jump at run-time. Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
Diffstat (limited to 'sysdeps/x86_64/Makefile')
| -rw-r--r-- | sysdeps/x86_64/Makefile | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile index 00120ca9ca..374bca80d0 100644 --- a/sysdeps/x86_64/Makefile +++ b/sysdeps/x86_64/Makefile @@ -1,6 +1,14 @@ # The i387 `long double' is a distinct type we support. long-double-fcts = yes +ifeq (yes,$(have-z-mark-plt)) +# Always generate DT_X86_64_PLT* tags. +sysdep-LDFLAGS += -Wl,-z,mark-plt +# Never generate DT_X86_64_PLT* tags on ld.so to avoid changing its own +# PLT. +LDFLAGS-rtld += -Wl,-z,nomark-plt +endif + ifeq ($(subdir),csu) gen-as-const-headers += link-defines.sym endif @@ -175,6 +183,25 @@ ifeq (no,$(build-hardcoded-path-in-tests)) tests-container += tst-glibc-hwcaps-cache endif +ifeq (yes,$(have-z-mark-plt)) +tests += \ + tst-plt-rewrite1 \ +# tests +modules-names += \ + tst-plt-rewritemod1 \ +# modules-names + +tst-plt-rewrite1-no-pie = yes +LDFLAGS-tst-plt-rewrite1 = -Wl,-z,now +LDFLAGS-tst-plt-rewritemod1.so = -Wl,-z,now +tst-plt-rewrite1-ENV = GLIBC_TUNABLES=glibc.cpu.plt_rewrite=1 LD_DEBUG=files:bindings +$(objpfx)tst-plt-rewrite1: $(objpfx)tst-plt-rewritemod1.so +$(objpfx)tst-plt-rewrite1.out: /dev/null $(objpfx)tst-plt-rewrite1 + $(tst-plt-rewrite1-ENV) $(make-test-out) > $@ 2>&1; \ + grep -q -E "changing 'bar' PLT entry in .*/elf/tst-plt-rewritemod1.so' to direct branch" $@; \ + $(evaluate-test) +endif + endif # $(subdir) == elf ifeq ($(subdir),csu) |