Re: arch/riscv/net/bpf_jit.h:241:30: sparse: sparse: cast truncates bits from constant value (7ff becomes ff)

[Randy Dunlap]

[add Luke Nelson]

[why on earth was this sent to me?]

On 7/25/23 16:34, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   af2e19389c2c1d8a299e04c5105b180ef0c5b5b5
> commit: 2d311f480b52eeb2e1fd432d64b78d82952c3808 riscv, bpf: Fix patch_text implicit declaration
> date:   5 months ago
> config: riscv-randconfig-r072-20230725 (https://download.01.org/0day-ci/archive/20230726/202307260704.dUElCrWU-lkp@xxxxxxxxx/config)
> compiler: riscv64-linux-gcc (GCC) 12.3.0
> reproduce: (https://download.01.org/0day-ci/archive/20230726/202307260704.dUElCrWU-lkp@xxxxxxxxx/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202307260704.dUElCrWU-lkp@xxxxxxxxx/
> 
> sparse warnings: (new ones prefixed by >>)
>    WARNING: invalid argument to '-march': '_zicbom_zihintpause'
>    arch/riscv/net/bpf_jit_comp64.c: note: in included file:
>>> arch/riscv/net/bpf_jit.h:241:30: sparse: sparse: cast truncates bits from constant value (7ff becomes ff)
> 
> vim +241 arch/riscv/net/bpf_jit.h
> 
> ca6cb5447ceca6 Luke Nelson 2020-03-04  238  
> ca6cb5447ceca6 Luke Nelson 2020-03-04  239  static inline u32 rv_s_insn(u16 imm11_0, u8 rs2, u8 rs1, u8 funct3, u8 opcode)
> ca6cb5447ceca6 Luke Nelson 2020-03-04  240  {
> ca6cb5447ceca6 Luke Nelson 2020-03-04 @241  	u8 imm11_5 = imm11_0 >> 5, imm4_0 = imm11_0 & 0x1f;
> ca6cb5447ceca6 Luke Nelson 2020-03-04  242  
> ca6cb5447ceca6 Luke Nelson 2020-03-04  243  	return (imm11_5 << 25) | (rs2 << 20) | (rs1 << 15) | (funct3 << 12) |
> ca6cb5447ceca6 Luke Nelson 2020-03-04  244  		(imm4_0 << 7) | opcode;
> ca6cb5447ceca6 Luke Nelson 2020-03-04  245  }
> ca6cb5447ceca6 Luke Nelson 2020-03-04  246  
> 
> :::::: The code at line 241 was first introduced by commit
> :::::: ca6cb5447ceca6a87d6b62c9e5d41042c34f7ffa riscv, bpf: Factor common RISC-V JIT code
> 
> :::::: TO: Luke Nelson <lukenels@xxxxxxxxxxxxxxxxx>
> :::::: CC: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> 

-- 
~Randy