There is a problem with the current elf loader for risc-v: when a pair of
PCREL_HI20 / LO12 relocations are encountered, it is assumed that these
will follow each other immediately, as follows:
label:
auipc a0, %pcrel_hi(symbol) // R_RISCV_PCREL_HI20
load/store a0, %pcrel_lo(label)(a0) // R_RISCV_PCREL_LO12_I/S
With this assumption, the hi/lo relocations are both done when a hi20
relocation entry is encountered, first to the current instruction (addr)
and to the next instruction (addr + 4).
However, this assumption is wrong. There is nothing in the elf relocation
specification[1] that mandates this. Thus, the hi/lo relocation always
needs to first fixup the hi-part, and when the lo-part is encountered, it
needs to find the corresponding hi relocation entry, via the given "label".
This necessitates (re-)visiting the relocation entries for the current
section as well as looking for "label" in the symbol table.
The NuttX elf loader does not allow such operations to be done in the
machine specific part, so this patch fixes the relocation issue by
introducing an architecture specific cache for the hi20 relocation and
symbol table entries. When a lo12 relocation is encountered, the cache
can be consulted to find the hi20 part.
[1] https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-elf.adoc
CC: icmp/icmp_input.c modlib/modlib_load.c: In function 'modlib_elfsize':
modlib/modlib_load.c:87:30: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
87 | textaddr = (FAR void *)phdr->p_vaddr;
| ^
cc1: all warnings being treated as errors
Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>
modlib/modlib_symbols.c: In function ‘modlib_symcallback’:
modlib/modlib_symbols.c:215:13: warning: implicit declaration of function ‘modlib_depend’; did you mean ‘modlib_read’? [-Wimplicit-function-declaration]
215 | ret = modlib_depend(exportinfo->modp, modp);
| ^~~~~~~~~~~~~
| modlib_read
Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>
CP: nuttx/include/nuttx/config.h
modlib/modlib_init.c:53: warning: "modlib_dumpbuffer" redefined
53 | # define modlib_dumpbuffer(m,b,n) binfodumpbuffer(m,b,n)
|
In file included from modlib/modlib_init.c:36:
nuttx/include/nuttx/lib/modlib.h:64: note: this is the location of the previous definition
64 | # define modlib_dumpbuffer(m,b,n) sinfodumpbuffer(m,b,n)
|
Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>
* build-globals.sh
- Only look in the nuttx for external symbols used when loading
dynamic shared objects
* include/elf64.h
- Correct the type of fields in the Elf64_Phdr structure
* libs/libc/dlfcn/lib_dlclose.c
- Distinguish between ET_DYN and other objects as the former
has both text and data in a single allocation to reserve
GOT offsets
* libs/libc/dlfcn/lib_dlopen.c
- Code formatting
* libs/libc/modlib/modlib_bind.c
- Distinguish between relocation entry sizes by section type
- Handle RELA style relocations
* libs/libc/modlib/modlib_globals.S
- Formatting fixes
- Symbols should not be weak - they exist or they don't
* include/nuttx/lib/modlib.h
- Add an inidcator to module_s to distinguish between ET_DYN and other
* libs/libc/modlib/modlib_load.c
- ET_DYN objects need to keep the relative displacement between the text
and data sections due to GOT references from the former to the latter.
This also implies that linking may require modification from the default
for the shared objects being produced. For example, default alignment may
mean nearly 64K of wasted space.
* libs/libc/modlib/modlib_unload.c
sched/module/mod_rmmod.c
- Distingusih between freeing of ET_DYN storage and other as the former
is a single allocation.
* libs/libc/modlib/mod_insmod.c
- Cater for ET_DYN objects having init and preinit sections
1. Update all CMakeLists.txt to adapt to new layout
2. Fix cmake build break
3. Update all new file license
4. Fully compatible with current compilation environment(use configure.sh or cmake as you choose)
------------------
How to test
From within nuttx/. Configure:
cmake -B build -DBOARD_CONFIG=sim/nsh -GNinja
cmake -B build -DBOARD_CONFIG=sim:nsh -GNinja
cmake -B build -DBOARD_CONFIG=sabre-6quad/smp -GNinja
cmake -B build -DBOARD_CONFIG=lm3s6965-ek/qemu-flat -GNinja
(or full path in custom board) :
cmake -B build -DBOARD_CONFIG=$PWD/boards/sim/sim/sim/configs/nsh -GNinja
This uses ninja generator (install with sudo apt install ninja-build). To build:
$ cmake --build build
menuconfig:
$ cmake --build build -t menuconfig
--------------------------
2. cmake/build: reformat the cmake style by cmake-format
https://github.com/cheshirekow/cmake_format
$ pip install cmakelang
$ for i in `find -name CMakeLists.txt`;do cmake-format $i -o $i;done
$ for i in `find -name *\.cmake`;do cmake-format $i -o $i;done
Co-authored-by: Matias N <matias@protobits.dev>
Signed-off-by: chao an <anchao@xiaomi.com>
* build-globals.sh
- Macros for defining symbols etc. based on assembler in use
- Use the System.map to get all the nuttx symbols
* libs/libc/modlib/modlib_globals.S
- Provide an empty skeleton. If the dynamic loading functions
are required then run build-global.sh after a clean build
using the skeleton. This will fill out the skeleton with the
symbols to be available to dynamically loaded modules.
* libs/libc/modlib/modlib_loadhdrs.c
- Fix case where there are no program headers are avaiable
* libs/libc/machine/arm/armv7-m/arch_elf.c
- Fix cast of error message parameters
* build-globals.sh
- Build the modlib_globals.S file used to resolve symbols when dynamically loading
* libs/libc/modlib/Make.defs
- Build modlib_globals.S for all targets
* libs/libc/modlib/modlib_load.c
- Calculate sizes and text/data addresses based on program headers rather than section headers
- Handle objects with no program headers
* libs/libc/modlib/modlib_bind.c
- Call modlib_readsym with pointer to symbol table
- Add modlib_relocatedyn to manage relocation of symbols with shared object (ET_DYN)
- Differentiate between ET_REL and ET_DYN objects
- Use arch independent symbol ELF_R_SYM
- Cast sizes to avoid warnings
* libs/libc/modlib/modlib_load.c
- Cast sizes to avoid warnings
* include/elf.h
- Add definitions that may be found in shared objects
* include/nuttx/lib/modlib.h
- Add parameter to modlib_readsym prototype
- Add prototypes for:
- modlib_insertsymtab
- modlib_findglobal
- Define Elf_Dyn and Elf_Off according to the elf architecture
- Add fields to mod_loadifno_s:
- Program headers
- Exported symbols
- Data section address
- Padding requirement
- Section index for dynamic symbol table
- Number of symbols exported
- Add prottotype for modlib_freesymtab
* libs/libc/dlfcn/lib_dlclose.c
- Free the symbol table when the dll is closed
* libs/libc/dlfcn/lib_dlopen.c
- Add dump of program headers to debug routine
- Differentiate between ET_REL and ET_DYN objects
* libs/libc/machine/arm/armv7-m/arch_elf.c
- Add handling of R_ARM_RELATIVE and R_ARM_JUMP slot relocation types
* libs/libc/modlib/modlib_loadshdrs.c
- Rename modlib_loadshdrs.c to modlib_loadhdrs.c
- Rename modlib_loadshdrs to modlib_loadhdrs
- Add code to load program headers
* libs/libc/modlib/modlib_symbols.c
- Define entry point structure
- Add offset parameter to modlib_symname() and use to find symbol names
- Add symtab section header parameter to modlib_readsym()
- Add offset parameter to modlib_symvalue() to locate symbol names
- Add modlib_insertsyntab() to create a symbol table for exporting and resolution
- Add findEP() to resolve a symbol in the modlib_global table
- Add modlib_findglobal() to find symbol in the modlib_global table
- Add modlib_freesymtab() to free the symbol table
* libs/libc/modlib/modlib_uninit.c
- Free header and sections from a module_loadinfo_s control block
* libs/libc/modlib/modlib_verify.c
- Handle ET_DYN shared objects
* libs/libc/modlib/modlib_globals.S
- Multi-target global table
- Define library APIs that may be resolved when loading a shared object
Restore the checks which got completely broken by the following change.
```
commit 15142a8b10
Author: anjiahao <anjiahao@xiaomi.com>
Date: Fri Apr 1 16:20:03 2022 +0800
modlib/modlib_bind:fix unsigned_compare with zero
Signed-off-by: anjiahao <anjiahao@xiaomi.com>
```
Pros:
* Reduce code differences
* Smaller allocations for !CONFIG_ARCH_USE_MODULE_TEXT
Cons:
* Likely to use more memory for !CONFIG_ARCH_USE_MODULE_TEXT in total
Tested with:
* sim:module on macOS
* esp32-devkit:nsh + CONFIG_MODULE on qemu
* lm3s6965-ek:qemu-protected + CONFIG_EXAMPLES_SOTEST on qemu
I've seen a module with 16 bytes .rodata alignment for xmm operations.
It was getting SEGV on sim/Linux because of the alignment issue.
The same module binary seems working fine after applying this patch.
Also, tested on sim/macOS and esp32 on qemu,
using a module with an artificially large alignment. (64 bytes)
When CONFIG_SYMTAB_ORDEREDBYNAME is selected most code will use
the ordered search function. When it is not selected no code will
use the ordered search function. This change merges the two
functions and varies its behaviour based on the config setting,
such that all callers can simply call the one search function
and get the best behaviour.
An additional configuration option allows leading underscores to
be stripped from symbols being relocated in loaded objects. This
allows toolchains which prefix C symbol with underscores to make
loadable ELF objects.
Found by clang-check:
modlib/modlib_sections.c:93:3: warning: Value stored to 'buffer' is never read
buffer = loadinfo->iobuffer;
^ ~~~~~~~~~~~~~~~~~~
1 warning generated.
