On 14/04/2016 16:49, Thomas Huth wrote:
> This test checks some special cases of the lswi instruction. Test
> works fine on real hardware, but in QEMU, this reveals a bug with
> the final "don't overwrite Ra" test (RA gets destroyed since the
> check in QEMU is still wrong).
> The code is based on the lswx test by Laurent Vivier.
>
> Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
> ---
> v2: Do not clobber r2 during the final test, since it is needed by
> the exception handler
>
> powerpc/emulator.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 124 insertions(+)
>
> diff --git a/powerpc/emulator.c b/powerpc/emulator.c
> index 3696d83..4dc341f 100644
> --- a/powerpc/emulator.c
> +++ b/powerpc/emulator.c
> @@ -71,6 +71,129 @@ static void test_64bit(void)
> report_prefix_pop();
> }
>
> +/**
> + * Test 'Load String Word Immediate' instruction
> + */
> +static void test_lswi(void)
> +{
> + int i;
> + char addr[128];
> + uint64_t regs[32];
> +
> + report_prefix_push("lswi");
> +
> + /* fill memory with sequence */
> + for (i = 0; i < 128; i++)
> + addr[i] = 1 + i;
> +
> + /* check incomplete register filling */
> + alignment = 0;
> + asm volatile ("li r12,-1;"
> + "mr r11, r12;"
> + "lswi r11, %[addr], %[len];"
> + "std r11, 0*8(%[regs]);"
> + "std r12, 1*8(%[regs]);"
> + ::
> + [len] "i" (3),
> + [addr] "b" (addr),
> + [regs] "r" (regs)
> + :
> + "r11", "r12", "memory");
> +
> +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
> + /*
> + * lswi is supposed to cause an alignment exception in little endian
> + * mode, but QEMU does not support it. So in case we do not get an
> + * exception, this is an expected failure and we run the other tests
> + */
> + report_xfail("alignment", !alignment, alignment);
> + if (alignment) {
> + report_prefix_pop();
> + return;
> + }
> +#endif
> + report("partial", regs[0] == 0x01020300 && regs[1] == (uint64_t)-1);
> +
> + /* check NB = 0 ==> 32 bytes. */
> + asm volatile ("li r19,-1;"
> + "mr r11, r19; mr r12, r19; mr r13, r19;"
> + "mr r14, r19; mr r15, r19; mr r16, r19;"
> + "mr r17, r19; mr r18, r19;"
> + "lswi r11, %[addr], %[len];"
> + "std r11, 0*8(%[regs]);"
> + "std r12, 1*8(%[regs]);"
> + "std r13, 2*8(%[regs]);"
> + "std r14, 3*8(%[regs]);"
> + "std r15, 4*8(%[regs]);"
> + "std r16, 5*8(%[regs]);"
> + "std r17, 6*8(%[regs]);"
> + "std r18, 7*8(%[regs]);"
> + "std r19, 8*8(%[regs]);"
> + ::
> + [len] "i" (0),
> + [addr] "b" (addr),
> + [regs] "r" (regs)
> + :
> + /* as 32 is the number of bytes,
> + * we should modify 32/4 = 8 regs, from r11 to r18
> + * We check r19 is unmodified by filling it with 1s
> + * before the instruction.
> + */
> + "r11", "r12", "r13", "r14", "r15", "r16", "r17",
> + "r18", "r19", "memory");
> +
> + report("length", regs[0] == 0x01020304 && regs[1] == 0x05060708 &&
> + regs[2] == 0x090a0b0c && regs[3] == 0x0d0e0f10 &&
> + regs[4] == 0x11121314 && regs[5] == 0x15161718 &&
> + regs[6] == 0x191a1b1c && regs[7] == 0x1d1e1f20 &&
> + regs[8] == (uint64_t)-1);
> +
> + /* check wrap around to r0 */
> + asm volatile ("li r31,-1;"
> + "mr r0, r31;"
> + "lswi r31, %[addr], %[len];"
> + "std r31, 0*8(%[regs]);"
> + "std r0, 1*8(%[regs]);"
> + ::
> + [len] "i" (8),
> + [addr] "b" (addr),
> + [regs] "r" (regs)
> + :
> + /* modify two registers from r31, wrap around to r0 */
> + "r31", "r0", "memory");
> +
> + report("wrap around to r0", regs[0] == 0x01020304 &&
> + regs[1] == 0x05060708);
> +
> + /* check wrap around doesn't break RA */
> + asm volatile ("mr r29,r1\n"
> + "li r31,-1\n"
> + "mr r0,r31\n"
> + "mr r1, %[addr]\n"
> + ".long 0x7fe154aa\n" /* lswi r31, r1, 10 */
Perhaps you can add a comment explaining why you are using a .long
instead of the mnemonic?
Anyway:
Reviewed-by: Laurent Vivier <lvivier@xxxxxxxxxx>
> + "std r31, 0*8(%[regs])\n"
> + "std r0, 1*8(%[regs])\n"
> + "std r1, 2*8(%[regs])\n"
> + "mr r1,r29\n"
> + ::
> + [addr] "r" (addr),
> + [regs] "r" (regs)
> + :
> + /* loading three registers from r31 wraps around to r1,
> + * r1 is saved to r29, as adding it to the clobber
> + * list doesn't protect it
> + */
> + "r0", "r29", "r31", "memory");
> +
> + /* doc says it is invalid, real proc stops when it comes to
> + * overwrite the register.
> + * In all the cases, the register must stay untouched
> + */
> + report("Don't overwrite Ra", regs[2] == (uint64_t)addr);
> +
> + report_prefix_pop();
> +}
> +
> /*
> * lswx: Load String Word Indexed X-form
> *
> @@ -235,6 +358,7 @@ int main(int argc, char **argv)
> test_64bit();
> test_illegal();
> test_lswx();
> + test_lswi();
>
> report_prefix_pop();
>
>
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