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The sbi_ecall() function arguments are not in the same order as the ecall arguments, so we end up re-ordering the registers before the ecall which is useless and costly. So simply reorder the arguments in the same way as expected by ecall. Instead of reordering directly the arguments of sbi_ecall(), use a proxy macro since the current ordering is more natural. Before: Dump of assembler code for function sbi_ecall: 0xffffffff800085e0 <+0>: add sp,sp,-32 0xffffffff800085e2 <+2>: sd s0,24(sp) 0xffffffff800085e4 <+4>: mv t1,a0 0xffffffff800085e6 <+6>: add s0,sp,32 0xffffffff800085e8 <+8>: mv t3,a1 0xffffffff800085ea <+10>: mv a0,a2 0xffffffff800085ec <+12>: mv a1,a3 0xffffffff800085ee <+14>: mv a2,a4 0xffffffff800085f0 <+16>: mv a3,a5 0xffffffff800085f2 <+18>: mv a4,a6 0xffffffff800085f4 <+20>: mv a5,a7 0xffffffff800085f6 <+22>: mv a6,t3 0xffffffff800085f8 <+24>: mv a7,t1 0xffffffff800085fa <+26>: ecall 0xffffffff800085fe <+30>: ld s0,24(sp) 0xffffffff80008600 <+32>: add sp,sp,32 0xffffffff80008602 <+34>: ret After: Dump of assembler code for function __sbi_ecall: 0xffffffff8000b6b2 <+0>: add sp,sp,-32 0xffffffff8000b6b4 <+2>: sd s0,24(sp) 0xffffffff8000b6b6 <+4>: add s0,sp,32 0xffffffff8000b6b8 <+6>: ecall 0xffffffff8000b6bc <+10>: ld s0,24(sp) 0xffffffff8000b6be <+12>: add sp,sp,32 0xffffffff8000b6c0 <+14>: ret Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Reviewed-by: Atish Patra <atishp@rivosinc.com> Reviewed-by: Yunhui Cui <cuiyunhui@bytedance.com> Link: https://lore.kernel.org/r/20240322112629.68170-1-alexghiti@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.