diff options
| author | Greg Ungerer <gerg@kernel.org> | 2023-11-28 23:29:43 +1000 |
|---|---|---|
| committer | Waldemar Brodkorb <wbx@openadk.org> | 2023-12-12 05:51:34 +0100 |
| commit | 74d5b684253ce61404c1b72f2726599f00eb0a14 (patch) | |
| tree | 6aab797e63c89b3c9575c2df35440499a35f5b00 /extra | |
| parent | 75a5fc9e5033f47e955406e300a070004c14b8ae (diff) | |
elf: support ELF binaries in noMMU
The Linux kernels ELF-FDPIC binfmt program loader can support loading and
running conventional ELF format binaries on noMMU kernels when compiled
appropriately. That is when they are constant displacement binaries such
as generated using the -pie compile option.
Add a configure option to allow selecting ELF binary support in noMMU
mode configurations on architectures that support this. The main
requirement is to generate the ldso run-time loader to perform relocation
at load time. These configurations do not support shared libraries, so
there is no need to generate a full shared library, only the static
version is required.
The use of ELF format binaries does mean a slightly simpler toolchain
generation (does not require a -uclinux- for some architectures) and does
not require an extra tool like elf2flt.
This initial support targets M68K, ARM and RISC-V architectures. No kernel
changes are required, the required support for this is already in mainline
kernels (certainly as of linux-6.6).
Note that for the M68K and ARM architectures that the initialized
registers and stack layout at process startup is slightly different for
the flat format loader and the ELF/ELF-FDPIC loaders. So we need some
changes to the startup code (crt1.S) for them.
I have not done extensive testing outside of M68K, ARM and RISC-V.
I had to make changes to a couple of the dl-startup.h architecture files
to get them to build for this noMMU case. I did not dig down too deep on
the reasons, but they still seem ok for the MMU case as well.
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
Diffstat (limited to 'extra')
| -rw-r--r-- | extra/Configs/Config.in | 9 | ||||
| -rw-r--r-- | extra/Configs/Config.in.arch | 8 |
2 files changed, 15 insertions, 2 deletions
diff --git a/extra/Configs/Config.in b/extra/Configs/Config.in index 287db13d2..18748d54b 100644 --- a/extra/Configs/Config.in +++ b/extra/Configs/Config.in @@ -333,8 +333,9 @@ config STATIC_PIE bool "Add support for Static Position Independent Executables (PIE)" default n depends on DOPIC && !UCLIBC_FORMAT_FDPIC_ELF && \ - (TARGET_arm || TARGET_i386 || TARGET_x86_64 || TARGET_aarch64 || \ - TARGET_mips || TARGET_xtensa || TARGET_powerpc) + (TARGET_aarch64 || TARGET_arm || TARGET_i386 || \ + TARGET_m68k || TARGET_mips || TARGET_powerpc || \ + TARGET_riscv64 || TARGET_x86_64 || TARGET_xtensa) config ARCH_HAS_NO_SHARED bool @@ -346,9 +347,13 @@ config ARCH_HAS_NO_LDSO config ARCH_HAS_UCONTEXT bool +config HAVE_LDSO + bool + config HAVE_SHARED bool "Enable shared libraries" depends on !ARCH_HAS_NO_SHARED + select HAVE_LDSO default y help If you wish to build uClibc with support for shared libraries then diff --git a/extra/Configs/Config.in.arch b/extra/Configs/Config.in.arch index 91b639493..4bcf3ff3f 100644 --- a/extra/Configs/Config.in.arch +++ b/extra/Configs/Config.in.arch @@ -10,6 +10,14 @@ if !ARCH_USE_MMU choice prompt "Target File Format" +config UCLIBC_FORMAT_ELF + bool "ELF (using ELF_FDPIC loader)" + depends on !ARCH_USE_MMU && (TARGET_arm || TARGET_m68k || \ + TARGET_riscv64) + select DOPIC + select STATIC_PIE + select ARCH_HAS_NO_SHARED + select HAVE_LDSO config UCLIBC_FORMAT_FDPIC_ELF bool "FDPIC ELF" depends on !ARCH_USE_MMU && (TARGET_bfin || TARGET_frv || TARGET_arm) |