[compiler-rt] r225215 - tests: correct builtins test if built under -mthumb on ARM

[Alexey Samsonov]

Hi Saleem.

How do you run the builtins test suite? Do you, by any chance have local
changes that would allow to run them in CMake build, and can be upstreamed
with reasonable effort? :)

On Mon, Jan 5, 2015 at 1:54 PM, Saleem Abdulrasool <compnerd at compnerd.org>
wrote:

> Author: compnerd
> Date: Mon Jan  5 15:54:50 2015
> New Revision: 225215
>
> URL: http://llvm.org/viewvc/llvm-project?rev=225215&view=rev
> Log:
> tests: correct builtins test if built under -mthumb on ARM
>
> The clear_cache and enable_execute_stack tests attempt to memcpy the
> definition
> of a function into a buffer before executing the function.  The problem
> with
> this approach is that on some targets (ARM with thumb mode compilation,
> MIPS
> with MIPS16 codegen or uMIPS), you would use a pointer which is incorrect
> (it
> would be off-by-one) due to the ISA selection being encoded into the
> address.
> This ensures that the function address is retrieved correctly in all cases.
>
> Modified:
>     compiler-rt/trunk/test/builtins/Unit/clear_cache_test.c
>     compiler-rt/trunk/test/builtins/Unit/enable_execute_stack_test.c
>
> Modified: compiler-rt/trunk/test/builtins/Unit/clear_cache_test.c
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/builtins/Unit/clear_cache_test.c?rev=225215&r1=225214&r2=225215&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/test/builtins/Unit/clear_cache_test.c (original)
> +++ compiler-rt/trunk/test/builtins/Unit/clear_cache_test.c Mon Jan  5
> 15:54:50 2015
> @@ -38,7 +38,18 @@ int func2()
>      return 2;
>  }
>
> -
> +void *__attribute__((noinline))
> +memcpy_f(void *dst, const void *src, size_t n) {
> +// ARM and MIPS nartually align functions, but use the LSB for ISA
> selection
> +// (THUMB, MIPS16/uMIPS respectively).  Ensure that the ISA bit is
> ignored in
> +// the memcpy
> +#if defined(__arm__) || defined(__mips__)
> +  return (void *)((uintptr_t)memcpy(dst, (void *)((uintptr_t)src & ~1),
> n) |
> +                  ((uintptr_t)src & 1));
> +#else
> +  return memcpy(dst, (void *)((uintptr_t)src), n);
> +#endif
> +}
>
>  unsigned char execution_buffer[128];
>
> @@ -59,16 +70,14 @@ int main()
>          return 1;
>
>      // verify you can copy and execute a function
> -    memcpy(execution_buffer, (void *)(uintptr_t)&func1, 128);
> +    pfunc f1 = (pfunc)memcpy_f(execution_buffer, func1, 128);
>      __clear_cache(execution_buffer, &execution_buffer[128]);
> -    pfunc f1 = (pfunc)(uintptr_t)execution_buffer;
>      if ((*f1)() != 1)
>          return 1;
>
>      // verify you can overwrite a function with another
> -    memcpy(execution_buffer, (void *)(uintptr_t)&func2, 128);
> +    pfunc f2 = (pfunc)memcpy_f(execution_buffer, func2, 128);
>      __clear_cache(execution_buffer, &execution_buffer[128]);
> -    pfunc f2 = (pfunc)(uintptr_t)execution_buffer;
>      if ((*f2)() != 2)
>          return 1;
>
>
> Modified: compiler-rt/trunk/test/builtins/Unit/enable_execute_stack_test.c
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/builtins/Unit/enable_execute_stack_test.c?rev=225215&r1=225214&r2=225215&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/test/builtins/Unit/enable_execute_stack_test.c
> (original)
> +++ compiler-rt/trunk/test/builtins/Unit/enable_execute_stack_test.c Mon
> Jan  5 15:54:50 2015
> @@ -45,8 +45,18 @@ int func2()
>      return 2;
>  }
>
> -
> -
> +void *__attribute__((noinline))
> +memcpy_f(void *dst, const void *src, size_t n) {
> +// ARM and MIPS nartually align functions, but use the LSB for ISA
> selection
> +// (THUMB, MIPS16/uMIPS respectively).  Ensure that the ISA bit is
> ignored in
> +// the memcpy
> +#if defined(__arm__) || defined(__mips__)
> +  return (void *)((uintptr_t)memcpy(dst, (void *)((uintptr_t)src & ~1),
> n) |
> +                  ((uintptr_t)src & 1));
> +#else
> +  return memcpy(dst, (void *)((uintptr_t)src), n);
> +#endif
> +}
>
>  int main()
>  {
> @@ -55,16 +65,14 @@ int main()
>      __enable_execute_stack(execution_buffer);
>
>      // verify you can copy and execute a function
> -    memcpy(execution_buffer, (void *)(uintptr_t)&func1, 128);
> +    pfunc f1 = (pfunc)memcpy_f(execution_buffer, func1, 128);
>      __clear_cache(execution_buffer, &execution_buffer[128]);
> -    pfunc f1 = (pfunc)(uintptr_t)execution_buffer;
>      if ((*f1)() != 1)
>          return 1;
>
>      // verify you can overwrite a function with another
> -    memcpy(execution_buffer, (void *)(uintptr_t)&func2, 128);
> +    pfunc f2 = (pfunc)memcpy_f(execution_buffer, func2, 128);
>      __clear_cache(execution_buffer, &execution_buffer[128]);
> -    pfunc f2 = (pfunc)(uintptr_t)execution_buffer;
>      if ((*f2)() != 2)
>          return 1;
>
>
>
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-- 
Alexey Samsonov
vonosmas at gmail.com
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