[Bug]: Cannot build RISC-V Assembly for SHA3 in Debug

[EAlexJ]

Contact Details

alex@minres.com

Version

5.9.1 (commit 6a3eb6f)

Description

I am trying to build a wolfssl setup with assembly routines for a RISC-V system.
My setup builds fine when building for Release mode, but fails for Debug.

EDIT: I did not mention this explicitly, but I am building for rv64gc with some other extensions.

Reproduction steps

If this cannot be reproduced by this information alone, I can share more details about my setup to allow for reproduction.

Relevant log output

wolfcrypt/src/port/riscv/riscv-64-sha3.c: In function 'BlockSha3':
wolfcrypt/src/port/riscv/riscv-64-sha3.c:146:5: error: 'asm' operand has impossible constraints or there are not enough registers
  146 |     __asm__ __volatile__ (
      |     ^~~~~~~

[dgarske]

Hi @EAlexJ ,

Please share how you are building (the configure) and the compiler details. We have done testing with SiFive Unleashed and PolarFire SoC. It would also be helpful to know the details of the RISC-V core you are building for and what optional features of your core are enabled or not (the extensions).

Thanks, David Garske, wolfSSL

[EAlexJ]

I assume you are referring to the recap of options that gets printed:

---
./configure flags: --host=riscv64-unknown-elf --enable-riscv-asm --enable-debug --enable-debug-code-points --enable-debug-trace-errcodes --enable-usersettings --disable-benchmark --disable-examples --disable-crypttests --disable-threadlocal --disable-asyncthreads --prefix=<...>/build/Debug/third-party/wolfssl --enable-mlkem --enable-kyber --enable-dilithium --enable-ecc --enable-supportedcurves --enable-tls13 host_alias=riscv64-unknown-elf 'CFLAGS=  -march=rv64gc_zicsr_zifencei -mabi=lp64 -mcmodel=medany <include dirs>'
---

What is omitted in this output is the user_settings.h. Mine is currently a huge mess, so here is only a snippet which should cover the most important defines:

#define WOLFSSL_TLS13
#define WOLFSSL_NO_TLS12
#define NO_OLD_TLS

#define HAVE_AESGCM
#define GCM_TABLE
#define WOLFSSL_SHA3
#define WOLFSSL_HAVE_MLKEM
#define WOLFSSL_SHAKE128
#define WOLFSSL_SHAKE256

#define NX_INCLUDE_USER_DEFINE_FILE
#define WOLFSSL_NO_SOCK
#define WOLFSSL_NO_GETPID
#define THREADX
#define HAVE_NETX

#if __riscv_xlen == 32
#define WOLFSSL_SP_RISCV32
#define WOLFSSL_GENERAL_ALIGNMENT 4
#endif
#if __riscv_xlen == 64
#define WOLFSSL_SP_RISCV64
#define WOLFSSL_GENERAL_ALIGNMENT 8
#define WOLFSSL_RISCV_ASM
#define WOLFSSL_USE_ALIGN
#endif

I am using the following compiler
riscv64-unknown-elf-gcc (crosstool-NG 1.28.0) 15.2.0

I am targeting a virtual platform which supports most of the currently ratified instruction extensions.

Let me know if this is sufficient for you to reproduce the error I am seeing

[SparkiDev]

Hi @EAlexJ

Can you please try using -fomit-frame-pointer.
The debug build usually requires extra registers for the frame pointer and we are using all the registers already!

Sean

[SparkiDev]

Hi @EAlexJ,

I've added WC_OMIT_FRAME_POINTER to BlockSha3 in PR: #10530
This should do the same as -fomit-frame-poniter only it is just for that function

Let me know if this works as an alternative.

Thanks,
Sean

[EAlexJ]

Can confirm that his now works.