Unverified Commit b51fc88c authored by Palmer Dabbelt's avatar Palmer Dabbelt
Browse files

Merge patch series "riscv: Add remaining module relocations and tests" 

Charlie Jenkins <charlie@rivosinc.com> says:

A handful of module relocations were missing, this patch includes the
remaining ones. I also wrote some test cases to ensure that module
loading works properly. Some relocations cannot be supported in the
kernel, these include the ones that rely on thread local storage and
dynamic linking.

This patch also overhauls the implementation of ADD/SUB/SET/ULEB128
relocations to handle overflow. "Overflow" is different for ULEB128
since it is a variable-length encoding that the compiler can be expected
to generate enough space for. Instead of overflowing, ULEB128 will
expand into the next 8-bit segment of the location.

A psABI proposal [1] was merged that mandates that SET_ULEB128 and
SUB_ULEB128 are paired, however the discussion following the merging of
the pull request revealed that while the pull request was valid, it
would be better for linkers to properly handle this overflow. This patch
proactively implements this methodology for future compatibility.

This can be tested by enabling KUNIT, RUNTIME_KERNEL_TESTING_MENU, and
RISCV_MODULE_LINKING_KUNIT.

[1] https://github.com/riscv-non-isa/riscv-elf-psabi-doc/pull/403

* b4-shazam-merge:
  riscv: Add tests for riscv module loading
  riscv: Add remaining module relocations
  riscv: Avoid unaligned access when relocating modules

Link: https://lore.kernel.org/r/20231101-module_relocations-v9-0-8dfa3483c400@rivosinc.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parents 946bb33d af71bc19

arch/riscv/Kconfig.debug

+1 −0
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source "arch/riscv/kernel/tests/Kconfig.debug"

arch/riscv/include/uapi/asm/elf.h

+4 −1
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@@ -49,6 +49,7 @@ typedef union __riscv_fp_state elf_fpregset_t; 
#define R_RISCV_TLS_DTPREL64	9

#define R_RISCV_TLS_TPREL32	10

#define R_RISCV_TLS_TPREL64	11

#define R_RISCV_IRELATIVE	58



/* Relocation types not used by the dynamic linker */

#define R_RISCV_BRANCH		16
@@ -81,7 +82,6 @@ typedef union __riscv_fp_state elf_fpregset_t; 
#define R_RISCV_ALIGN		43

#define R_RISCV_RVC_BRANCH	44

#define R_RISCV_RVC_JUMP	45

#define R_RISCV_LUI		46

#define R_RISCV_GPREL_I		47

#define R_RISCV_GPREL_S		48

#define R_RISCV_TPREL_I		49
@@ -93,6 +93,9 @@ typedef union __riscv_fp_state elf_fpregset_t; 
#define R_RISCV_SET16		55

#define R_RISCV_SET32		56

#define R_RISCV_32_PCREL	57

#define R_RISCV_PLT32		59

#define R_RISCV_SET_ULEB128	60

#define R_RISCV_SUB_ULEB128	61





#endif /* _UAPI_ASM_RISCV_ELF_H */

arch/riscv/kernel/Makefile

+1 −0
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@@ -57,6 +57,7 @@ obj-y += stacktrace.o 
obj-y	+= cacheinfo.o

obj-y	+= patch.o

obj-y	+= probes/

obj-y	+= tests/

obj-$(CONFIG_MMU) += vdso.o vdso/



obj-$(CONFIG_RISCV_MISALIGNED)	+= traps_misaligned.o

arch/riscv/kernel/module.c

+499 −104

File changed.

Preview size limit exceeded, changes collapsed.

arch/riscv/kernel/tests/Kconfig.debug

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# SPDX-License-Identifier: GPL-2.0-only

menu "arch/riscv/kernel Testing and Coverage"



config AS_HAS_ULEB128

	def_bool $(as-instr,.reloc label$(comma) R_RISCV_SET_ULEB128$(comma) 127\n.reloc label$(comma) R_RISCV_SUB_ULEB128$(comma) 127\nlabel:\n.word 0)



menuconfig RUNTIME_KERNEL_TESTING_MENU

       bool "arch/riscv/kernel runtime Testing"

       def_bool y

       help

         Enable riscv kernel runtime testing.



if RUNTIME_KERNEL_TESTING_MENU



config RISCV_MODULE_LINKING_KUNIT

       bool "KUnit test riscv module linking at runtime" if !KUNIT_ALL_TESTS

       depends on KUNIT

       default KUNIT_ALL_TESTS

       help

         Enable this option to test riscv module linking at boot. This will

	 enable a module called "test_module_linking".



         KUnit tests run during boot and output the results to the debug log

         in TAP format (http://testanything.org/). Only useful for kernel devs

         running the KUnit test harness, and not intended for inclusion into a

         production build.



         For more information on KUnit and unit tests in general please refer

         to the KUnit documentation in Documentation/dev-tools/kunit/.



         If unsure, say N.



endif # RUNTIME_TESTING_MENU



endmenu # "arch/riscv/kernel runtime Testing"