On Sun, Nov 24, 2019 at 04:35:29AM +0000, Justin Hibbits wrote:
> Author: jhibbits
> Date: Sun Nov 24 04:35:29 2019
> New Revision: 355045
> URL: https://svnweb.freebsd.org/changeset/base/355045
> 
> Log:
>   rtld/powerpc: Fix _rtld_bind_start for powerpcspe
>   
>   Summary:
>   We need to save off the full 64-bit register, not just the low 32 bits,
>   of all registers getting saved off in _rtld_bind_start.  Additionally,
>   we need to save off the other SPE registers (SPEFSCR and accumulator),
>   so that their program state is not affected by the PLT resolver.
Why do you need to save these registers ?  Why would rtld touch them ?

>   
>   Reviewed by:        bdragon
>   Differential Revision:      https://reviews.freebsd.org/D22520
> 
> Modified:
>   head/libexec/rtld-elf/powerpc/rtld_start.S
> 
> Modified: head/libexec/rtld-elf/powerpc/rtld_start.S
> ==============================================================================
> --- head/libexec/rtld-elf/powerpc/rtld_start.S        Sun Nov 24 02:27:50 
> 2019        (r355044)
> +++ head/libexec/rtld-elf/powerpc/rtld_start.S        Sun Nov 24 04:35:29 
> 2019        (r355045)
> @@ -30,6 +30,7 @@
>   */
>  
>  #include <machine/asm.h>
> +#include <machine/spr.h>     /* For SPR_SPEFSCR if needed. */
>  
>  .extern _GLOBAL_OFFSET_TABLE_
>  .extern _DYNAMIC
> @@ -101,6 +102,20 @@ _ENTRY(.rtld_start)
>       li      %r0,1           /* _exit() */
>       sc
>  
> +#ifdef __SPE__
> +/* stack space for 30 GPRs + SPEFSCR/ACC/lr/cr */
> +#define      NREGS           31
> +#define      GPRWIDTH        8
> +#define      FUDGE           4       /* Fudge factor for alignment */
> +#else
> +/* stack space for 30 GPRs + lr/cr */
> +#define      NREGS           30
> +#define      GPRWIDTH        4
> +#define      FUDGE           0
> +#endif
> +/* Stack frame needs the 12-byte ABI frame plus fudge factor. */
> +#define      STACK_SIZE      (NREGS * GPRWIDTH + 4 * 2 + 12 + FUDGE)
> +
>  /*
>   * _rtld_bind_secureplt_start()
>   *
> @@ -110,8 +125,12 @@ _ENTRY(.rtld_start)
>   * So for bss-plt, we multiply the index by 12 to get the offset.
>   */
>  _ENTRY(_rtld_bind_secureplt_start)
> -     stwu    %r1,-160(%r1)           # stack space for 29 regs + r0/lr/cr
> +     stwu    %r1,-STACK_SIZE(%r1)
> +#ifdef __SPE__
> +     evstdd  %r0,24(%r1)
> +#else
>       stw     %r0,20(%r1)             # save r0
> +#endif
>  
>       /*
>        * Instead of division which is costly we will use multiplicative
> @@ -137,28 +156,113 @@ _ENTRY(_rtld_bind_secureplt_start)
>       .globl  _rtld_bind
>  
>  _ENTRY(_rtld_bind_start)
> -     stwu    %r1,-160(%r1)           # stack space for 29 regs + r0/lr/cr
> +     stwu    %r1,-STACK_SIZE(%r1)
> +#ifdef __SPE__
> +     evstdd  %r0,24(%r1)
> +#else
>       stw     %r0,20(%r1)             # save r0
> +#endif
>  1:
>       mflr    %r0
>       stw     %r0,16(%r1)             # save lr
>       mfcr    %r0
>       stw     %r0,12(%r1)             # save cr
> +#ifdef __SPE__
> +     evstdd  %r3, 32(%r1)
> +     evstdd  %r4, 40(%r1)
> +     evstdd  %r5, 48(%r1)
> +     evstdd  %r6, 56(%r1)
> +     evstdd  %r7, 64(%r1)
> +     evstdd  %r8, 72(%r1)
> +     evstdd  %r9, 80(%r1)
> +     evstdd  %r10, 88(%r1)
> +     evstdd  %r11, 96(%r1)
> +     evstdd  %r12, 104(%r1)
> +     evstdd  %r13, 112(%r1)
> +     evstdd  %r14, 120(%r1)
> +     evstdd  %r15, 128(%r1)
> +     evstdd  %r16, 136(%r1)
> +     evstdd  %r17, 144(%r1)
> +     evstdd  %r18, 152(%r1)
> +     evstdd  %r19, 160(%r1)
> +     evstdd  %r20, 168(%r1)
> +     evstdd  %r21, 176(%r1)
> +     evstdd  %r22, 184(%r1)
> +     evstdd  %r23, 192(%r1)
> +     evstdd  %r24, 200(%r1)
> +     evstdd  %r25, 208(%r1)
> +     evstdd  %r26, 216(%r1)
> +     evstdd  %r27, 224(%r1)
> +     evstdd  %r28, 232(%r1)
> +     evstdd  %r29, 240(%r1)
> +     evstdd  %r30, 248(%r1)
> +     li      %r3, 256
> +     evstddx %r31, %r1, %r3
> +     evxor   %r0, %r0, %r0
> +     li      %r3, 264
> +     evmwumiaa       %r0, %r0, %r0
> +     evstddx %r0, %r1, %r3
> +     mfspr   %r3, SPR_SPEFSCR
> +     stw     %r3, 20(%r1)
> +#else
>       stmw    %r3,24(%r1)             # save r3-r31
> +#endif
>  
>       mr      %r3,%r12                # obj
>       mulli   %r4,%r11,12             # rela index * sizeof(Elf_Rela)
>       bl      _rtld_bind              # target addr = _rtld_bind(obj, reloff)
>       mtctr   %r3                     # move absolute target addr into ctr
>  
> +#ifdef __SPE__
> +     lwz     %r3, 20(%r1)
> +     mtspr   SPR_SPEFSCR, %r3
> +     li      %r3, 264
> +     evlddx  %r0, %r3, %r1
> +     evmra   %r0, %r0
> +     evldd   %r3, 32(%r1)
> +     evldd   %r4, 40(%r1)
> +     evldd   %r5, 48(%r1)
> +     evldd   %r6, 56(%r1)
> +     evldd   %r7, 64(%r1)
> +     evldd   %r8, 72(%r1)
> +     evldd   %r9, 80(%r1)
> +     evldd   %r10, 88(%r1)
> +     evldd   %r11, 96(%r1)
> +     evldd   %r12, 104(%r1)
> +     evldd   %r13, 112(%r1)
> +     evldd   %r14, 120(%r1)
> +     evldd   %r15, 128(%r1)
> +     evldd   %r16, 136(%r1)
> +     evldd   %r17, 144(%r1)
> +     evldd   %r18, 152(%r1)
> +     evldd   %r19, 160(%r1)
> +     evldd   %r20, 168(%r1)
> +     evldd   %r21, 176(%r1)
> +     evldd   %r22, 184(%r1)
> +     evldd   %r23, 192(%r1)
> +     evldd   %r24, 200(%r1)
> +     evldd   %r25, 208(%r1)
> +     evldd   %r26, 216(%r1)
> +     evldd   %r27, 224(%r1)
> +     evldd   %r28, 232(%r1)
> +     evldd   %r29, 240(%r1)
> +     evldd   %r30, 248(%r1)
> +     li      %r0, 256
> +     evlddx  %r31, %r1, %r0
> +#else
>          lmw     %r3,24(%r1)          # restore r3-r31
> +#endif
>          lwz     %r0,12(%r1)          # restore cr
>          mtcr    %r0
>          lwz     %r0,16(%r1)          # restore lr
>          mtlr    %r0
> +#ifdef __SPE__
> +     evldd   %r0,24(%r1)
> +#else
>          lwz     %r0,20(%r1)          # restore r0
> +#endif
>  
> -        addi    %r1,%r1,160          # restore stack
> +        addi    %r1,%r1,STACK_SIZE   # restore stack
>          bctr                         # jump to target
>  
>  
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