kernel.git/arch/riscv/kernel/module.c, branch linux-4.19.y

riscv: Fix auipc+jalr relocation range checks

2022-03-16T12:20:27Z

commit 0966d385830de3470b7131db8e86c0c5bc9c52dc upstream. RISC-V can do PC-relative jumps with a 32bit range using the following two instructions: auipc t0, imm20 ; t0 = PC + imm20 * 2^12 jalr ra, t0, imm12 ; ra = PC + 4, PC = t0 + imm12 Crucially both the 20bit immediate imm20 and the 12bit immediate imm12 are treated as two's-complement signed values. For this reason the immediates are usually calculated like this: imm20 = (offset + 0x800) >> 12 imm12 = offset & 0xfff ..where offset is the signed offset from the auipc instruction. When the 11th bit of offset is 0 the addition of 0x800 doesn't change the top 20 bits and imm12 considered positive. When the 11th bit is 1 the carry of the addition by 0x800 means imm20 is one higher, but since imm12 is then considered negative the two's complement representation means it all cancels out nicely. However, this addition by 0x800 (2^11) means an offset greater than or equal to 2^31 - 2^11 would overflow so imm20 is considered negative and result in a backwards jump. Similarly the lower range of offset is also moved down by 2^11 and hence the true 32bit range is [-2^31 - 2^11, 2^31 - 2^11) Signed-off-by: Emil Renner Berthing Fixes: e2c0cdfba7f6 ("RISC-V: User-facing API") Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt Signed-off-by: Greg Kroah-Hartman

riscv: avoid the PIC offset of static percpu data in module beyond 2G limits

2020-03-25T07:06:07Z

[ Upstream commit 0cff8bff7af886af0923d5c91776cd51603e531f ] The compiler uses the PIC-relative method to access static variables instead of GOT when the code model is PIC. Therefore, the limitation of the access range from the instruction to the symbol address is +-2GB. Under this circumstance, the kernel cannot load a kernel module if this module has static per-CPU symbols declared by DEFINE_PER_CPU(). The reason is that kernel relocates the .data..percpu section of the kernel module to the end of kernel's .data..percpu. Hence, the distance between the per-CPU symbols and the instruction will exceed the 2GB limits. To solve this problem, the kernel should place the loaded module in the memory area [&_end-2G, VMALLOC_END]. Signed-off-by: Vincent Chen Suggested-by: Alexandre Ghiti Suggested-by: Anup Patel Tested-by: Alexandre Ghiti Tested-by: Carlos de Paula Signed-off-by: Palmer Dabbelt Signed-off-by: Sasha Levin

RISC-V: Silence some module warnings on 32-bit

2018-12-01T08:37:33Z

[ Upstream commit ef3a61406618291c46da168ff91acaa28d85944c ] Fixes: arch/riscv/kernel/module.c: In function 'apply_r_riscv_32_rela': ./include/linux/kern_levels.h:5:18: warning: format '%llx' expects argument of type 'long long unsigned int', but argument 3 has type 'Elf32_Addr' {aka 'unsigned int'} [-Wformat=] arch/riscv/kernel/module.c:23:27: note: format string is defined here arch/riscv/kernel/module.c: In function 'apply_r_riscv_pcrel_hi20_rela': ./include/linux/kern_levels.h:5:18: warning: format '%llx' expects argument of type 'long long unsigned int', but argument 3 has type 'Elf32_Addr' {aka 'unsigned int'} [-Wformat=] arch/riscv/kernel/module.c:104:23: note: format string is defined here arch/riscv/kernel/module.c: In function 'apply_r_riscv_hi20_rela': ./include/linux/kern_levels.h:5:18: warning: format '%llx' expects argument of type 'long long unsigned int', but argument 3 has type 'Elf32_Addr' {aka 'unsigned int'} [-Wformat=] arch/riscv/kernel/module.c:146:23: note: format string is defined here arch/riscv/kernel/module.c: In function 'apply_r_riscv_got_hi20_rela': ./include/linux/kern_levels.h:5:18: warning: format '%llx' expects argument of type 'long long unsigned int', but argument 3 has type 'Elf32_Addr' {aka 'unsigned int'} [-Wformat=] arch/riscv/kernel/module.c:190:60: note: format string is defined here arch/riscv/kernel/module.c: In function 'apply_r_riscv_call_plt_rela': ./include/linux/kern_levels.h:5:18: warning: format '%llx' expects argument of type 'long long unsigned int', but argument 3 has type 'Elf32_Addr' {aka 'unsigned int'} [-Wformat=] arch/riscv/kernel/module.c:214:24: note: format string is defined here arch/riscv/kernel/module.c: In function 'apply_r_riscv_call_rela': ./include/linux/kern_levels.h:5:18: warning: format '%llx' expects argument of type 'long long unsigned int', but argument 3 has type 'Elf32_Addr' {aka 'unsigned int'} [-Wformat=] arch/riscv/kernel/module.c:236:23: note: format string is defined here Signed-off-by: Olof Johansson Signed-off-by: Palmer Dabbelt Signed-off-by: Sasha Levin

RISC-V: Fix the rv32i kernel build

2018-07-04T21:12:53Z

These patches for building 32-bit RISC-V kernel. - Fix the compile errors and warnings on RV32I. - Fix some incompatible problem on RV32I. - Add format.h for compatible of print format. The fixed width integer types format for Elf_Addr will move to generic header by another patch. For now, there are some warning about unexpected argument of type on RV32I. Change in v1: - Fix some error in v1 - Remove implementation of fixed width integer types format for Elf_Addr.

RISC-V: fix R_RISCV_ADD32/R_RISCV_SUB32 relocations

2018-07-04T21:12:34Z

The R_RISCV_ADD32/R_RISCV_SUB32 relocations should add/subtract the address of the symbol (without overflow check), not its contents. Signed-off-by: Andreas Schwab Signed-off-by: Palmer Dabbelt

RISC-V: Change variable type for 32-bit compatible

2018-07-04T20:56:52Z

Signed-off-by: Zong Li Reviewed-by: Christoph Hellwig Signed-off-by: Palmer Dabbelt

RISC-V: Handle R_RISCV_32 in modules

2018-06-11T16:04:34Z

With CONFIG_MODVERSIONS=y the R_RISCV_32 relocation is used by the __kcrctab section. Signed-off-by: Andreas Schwab Signed-off-by: Palmer Dabbelt

RISC-V: Support SUB32 relocation type in kernel module

2018-04-03T03:00:55Z

Signed-off-by: Zong Li Signed-off-by: Palmer Dabbelt

RISC-V: Support ADD32 relocation type in kernel module

2018-04-03T03:00:55Z

Signed-off-by: Zong Li Signed-off-by: Palmer Dabbelt

RISC-V: Support ALIGN relocation type in kernel module

2018-04-03T03:00:55Z

Just fail on align type. Kernel modules loader didn't do relax like linker, it is difficult to remove or migrate the code, but the remnant nop instructions harm the performaace of module. We expect the building module with the no-relax option. Signed-off-by: Zong Li Signed-off-by: Palmer Dabbelt