RISC-V 32 no mul SP C: implement multiplication#9855
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douzzer merged 1 commit intowolfSSL:masterfrom Mar 5, 2026
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No multiplication instructions when M extension not included. Standard implementation of __muldi3 is not constant time. Include a constant time implementation when SP_NO_MUL_INSTRUCTION is defined Define it when compiling for RISC-V 32 and no multiplication extension. Also fix get_entry in SP C implementation to do constant time comparison.
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retest this please |
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@SparkiDev ran both the -O0 and -O3 builds and they check out 👍 |
douzzer
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Mar 5, 2026
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Description
No multiplication instructions when M extension not included. Standard implementation of __muldi3 is not constant time. Include a constant time implementation when SP_NO_MUL_INSTRUCTION is defined
Define it when compiling for RISC-V 32 and no multiplication extension.
Fixes zd#21264
Testing
./configure --disable-shared --enable-sp LDFLAGS=--static --host=riscv32 'CC=/opt/riscv32/bin/riscv32-unknown-linux-gnu-gcc -march=rv32ifd' --disable-asm