On Thu, Sep 30, 2021 at 1:56 AM Matteo Croce [off-list ref] wrote:

From: Matteo Croce <redacted>

The generic memset is defined as a byte at time write. This is always
safe, but it's slower than a 4 byte or even 8 byte write.

Write a generic memset which fills the data one byte at time until the
destination is aligned, then fills using the largest size allowed,
and finally fills the remaining data one byte at time.

Signed-off-by: Matteo Croce <redacted>
---
 arch/riscv/include/asm/string.h |  10 +--
 arch/riscv/kernel/Makefile      |   1 -
 arch/riscv/kernel/riscv_ksyms.c |  13 ----
 arch/riscv/lib/Makefile         |   1 -
 arch/riscv/lib/memset.S         | 113 --------------------------------
 arch/riscv/lib/string.c         |  41 ++++++++++++
 6 files changed, 44 insertions(+), 135 deletions(-)
 delete mode 100644 arch/riscv/kernel/riscv_ksyms.c
 delete mode 100644 arch/riscv/lib/memset.S

This patch causes the Linux kernel to hang if compile with LLVM/Clang.
Tested on Qemu.

Steps to compile with Clang:
make CC=clang  defconfig
make CC=clang -j

Boot log:

[    0.000000] Linux version 5.15.4-01003-g23eeaac40da8 (xxxxx@ubuntu)
(clang version 14.0.0 (https://github.com/llvm/llvm-project
6b715e9c4d9cc00f59906d48cd57f4c767229093), GNU ld (GNU Binutils)
2.36.1) #151 SMP Thu Nov 25 18:41:47 +08 2021
[    0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80200000
[    0.000000] Machine model: riscv-virtio,qemu
[    0.000000] earlycon: sbi0 at I/O port 0x0 (options '')
[    0.000000] printk: bootconsole [sbi0] enabled
[    0.000000] efi: UEFI not found.

Regards
Ley Foon