Re: Kernel freezes in r4k_flush_icache_range() with CONFIG_CPU_MIPS32_R2

["Maciej W. Rozycki" <macro@linux-mips.org>]

On Tue, 20 Dec 2005, Maxime Bizon wrote:

>     272c:       8c43000c        lw      v1,12(v0)
>     2730:       0060f809        jalr    v1
>     2734:       00000000        nop
>     2738:       3c020000        lui     v0,0x0
>     273c:       2442277c        addiu   v0,v0,10108   <----------
>     2740:       00400408        jr.hb   v0
>     2744:       00000000        nop
>     2748:       8fbf0028        lw      ra,40(sp)
>     274c:       8fb30024        lw      s3,36(sp)
>     2750:       8fb20020        lw      s2,32(sp)
>     2754:       8fb1001c        lw      s1,28(sp)
>     2758:       8fb00018        lw      s0,24(sp)
>     275c:       03e00008        jr      ra
>     2760:       27bd0030        addiu   sp,sp,48
>     2764:       3c020000        lui     v0,0x0
>     2768:       8c430018        lw      v1,24(v0)
>     276c:       0060f809        jalr    v1
>     2770:       00000000        nop
>     2774:       0800099c        j       2670 <r4k_flush_icache_range+0x4c>
>     2778:       3c030000        lui     v1,0x0
> 
> 0000277c <r4k_dma_cache_inv>:
> [...]
> 
> At offset 0x26ac and 0x273c, we can see that instruction_hazard() got
> duplicated due to inlining, and that the jr.hb is going to send us to
> 10108 (0x277C), outside the function...

 FYI, GCC 3.4.4 produces the following code which is clearly wrong:

        .align  2
        .align  3
        .ent    r4k_flush_icache_range
        .type   r4k_flush_icache_range, @function
r4k_flush_icache_range:
        .set    nomips16
        .frame  $sp,56,$31              # vars= 16, regs= 5/0, args= 16, gp= 0
        .mask   0x800f0000,-8
        .fmask  0x00000000,0
[...]
        lui     $2,%hi($L506)    # 239  movsi_internal/2        [length = 4]
        addiu   $2,$2,%lo($L506)         # 240  *lowsi  [length = 4]
#APP
                jr.hb   $2                                      

#NO_APP
        lw      $31,48($sp)      # 304  movsi_internal/4        [length = 4]
        lw      $19,44($sp)      # 305  movsi_internal/4        [length = 4]
        lw      $18,40($sp)      # 306  movsi_internal/4        [length = 4]
        lw      $17,36($sp)      # 307  movsi_internal/4        [length = 4]
        lw      $16,32($sp)      # 308  movsi_internal/4        [length = 4]
        .set    noreorder
        .set    nomacro
        j       $31      # 310  return_internal [length = 4]
        addiu   $sp,$sp,56       # 309  addsi3_internal/2       [length = 4]
        .set    macro
        .set    reorder

$L510:
        lui     $2,%hi(r4k_blast_icache)         # 181  movsi_internal/2        
[length = 4]
        lw      $3,%lo(r4k_blast_icache)($2)     # 182  movsi_internal/4        
[length = 4]
        jal     $3       # 183  call_internal/1 [length = 8]
        lui     $2,%hi($L506)    # 313  movsi_internal/2        [length = 4]
        addiu   $2,$2,%lo($L506)         # 314  *lowsi  [length = 4]
#APP
                jr.hb   $2                                      

#NO_APP
        lw      $31,48($sp)      # 316  movsi_internal/4        [length = 4]
        lw      $19,44($sp)      # 317  movsi_internal/4        [length = 4]
        lw      $18,40($sp)      # 318  movsi_internal/4        [length = 4]
        lw      $17,36($sp)      # 319  movsi_internal/4        [length = 4]
        lw      $16,32($sp)      # 320  movsi_internal/4        [length = 4]
        .set    noreorder
        .set    nomacro
        j       $31      # 322  return_internal [length = 4]
        addiu   $sp,$sp,56       # 321  addsi3_internal/2       [length = 4]
        .set    macro
        .set    reorder

$L508:
        lui     $2,%hi(r4k_blast_dcache)         # 67   movsi_internal/2        
[length = 4]
        lw      $3,%lo(r4k_blast_dcache)($2)     # 68   movsi_internal/4        
[length = 4]
        jal     $3       # 69   call_internal/1 [length = 8]
        .set    noreorder
        .set    nomacro
        b       $L512    # 334  jump    [length = 4]
        lui     $3,%hi(icache_size)      # 170  movsi_internal/2        [length 
= 4]
        .set    macro
        .set    reorder

$L506:
        .end    r4k_flush_icache_range

Please file a bug report at: "http://gcc.gnu.org/bugzilla/";.

  Maciej