riscv/qemu - qemu - Gitea: Git with a cup of tea

Author	SHA1	Message	Date
Richard Henderson	ee3b39c924	linux-user: Create vdso_sigreturn_region_{start,end} These variables will be populated from the vdso, and used for detecting whether we are executing the sigreturn. Signed-off-by: Richard Henderson <richard.henderson@linaro.org>	7 months ago
Ilya Leoshkevich	6e9dcfb906	linux-user: Fix GDB complaining about system-supplied DSO string table index When debugging qemu-user processes using gdbstub, the following warning appears every time: warning: BFD: warning: system-supplied DSO at 0x7f8253cc3000 has a corrupt string table index The reason is that QEMU does not map the VDSO's section headers. The VDSO's ELF header's e_shoff points to zeros, which GDB fails to parse. The difference with the kernel's VDSO is that the latter is mapped as a blob, ignoring program headers - which also don't cover the section table. QEMU, on the other hand, loads it as an ELF file. There appears to be no way to place section headers inside a section, and, therefore, no way to refer to them from a linker script. Also, ld hardcodes section headers to be non-loadable, see _bfd_elf_assign_file_positions_for_non_load(). In theory ld could be enhanced by implementing an "SHDRS" keyword in addition to the existing "FILEHDR" and "PHDRS". There are multiple ways to resolve the issue: - Copy VDSO as a blob in load_elf_vdso(). This would require creating specialized loader logic, that duplicates parts of load_elf_image(). - Fix up VDSO's PHDR size in load_elf_vdso(). This would require either duplicating the parsing logic, or adding an ugly parameter to load_elf_image(). - Fix up VDSO's PHDR size in gen-vdso. This is the simplest solution, so do it. There are two tricky parts: - Byte-swaps need to be done either on local copies, or in-place and then reverted in the end. To preserve the existing code structure, do the former for Sym and Dyn, and the latter for Ehdr, Phdr, and Shdr. - There must be no .bss, which is already the case - but having an explicit check is helpful to ensure correctness. To verify this change, I diffed the on-disk and the loaded VDSOs; the result does not show anything unusual, except for what seems to be an existing oversight (which should probably be fixed separately): │ Symbol table '.dynsym' contains 8 entries: │ Num: Value Size Type Bind Vis Ndx Name │ - 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND │ - 6: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LINUX_2.6.29 │ + 0: 00007f61075bf000 0 NOTYPE LOCAL DEFAULT UND │ + 6: 00007f61075bf000 0 OBJECT GLOBAL DEFAULT ABS LINUX_2.6.29 Fixes: `2fa536d107` ("linux-user: Add gen-vdso tool") Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-ID: <20241023202850.55211-1-iii@linux.ibm.com> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>	1 year ago
Richard Henderson	e34136d930	linux-user/ppc: Add vdso Add support in gen-vdso-elfn.c.inc for the DT_PPC64_OPT dynamic tag: this is an integer, so does not need relocation. Signed-off-by: Richard Henderson <richard.henderson@linaro.org>	3 years ago
Richard Henderson	2fa536d107	linux-user: Add gen-vdso tool This tool will be used for post-processing the linked vdso image, turning it into something that is easy to include into elfload.c. Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>	5 years ago