Fix the code reconstructing s87_tw (full tag word) from fx_sw (abridged
tag word) to correctly represent all register states. The previous code
only distinguished between empty/non-empty registers, and assigned
'regular value' to all non-empty registers. The new code explicitly
distinguishes the two other tag word values: empty and special.
---
sys/arch/x86/x86/fpu.c | 28 ++++++++++++++++++++------
tests/lib/libc/sys/t_ptrace_x86_wait.h | 2 --
2 files changed, 22 insertions(+), 8 deletions(-)
diff --git a/sys/arch/x86/x86/fpu.c b/sys/arch/x86/x86/fpu.c
index d89c78dcef47..c580f34b0615 100644
--- a/sys/arch/x86/x86/fpu.c
+++ b/sys/arch/x86/x86/fpu.c
@@ -668,7 +668,7 @@ fpu_sigreset(struct lwp *l)
static void
process_xmm_to_s87(const struct fxsave *sxmm, struct save87 *s87)
{
- unsigned int tag, ab_tag;
+ unsigned int tag, ab_tag, st;
const struct fpaccfx *fx_reg;
struct fpacc87 *s87_reg;
int i;
@@ -723,12 +723,28 @@ process_xmm_to_s87(const struct fxsave *sxmm, struct
save87 *s87)
return;
}
+ /* For ST(i), i = fpu_reg - top, we start with fpu_reg=7. */
+ st = 7 - ((sxmm->fx_sw >> 11) & 7);
tag = 0;
- /* Separate bits of abridged tag word with zeros */
- for (i = 0x80; i != 0; tag <<= 1, i >>= 1)
- tag |= ab_tag & i;
- /* Replicate and invert so that 0 => 0b11 and 1 => 0b00 */
- s87->s87_tw = (tag | tag >> 1) ^ 0xffff;
+ for (i = 0x80; i != 0; i >>= 1) {
+ tag <<= 2;
+ if (ab_tag & i) {
+ unsigned int exp;
+ /* Non-empty - we need to check ST(i) */
+ fx_reg = &sxmm->fx_87_ac[st];
+ exp = fx_reg->r.f87_exp_sign & 0x7fff;
+ if (exp == 0) {
+ if (fx_reg->r.f87_mantissa == 0)
+ tag |= 1; /* Zero */
+ else
+ tag |= 2; /* Denormal */
+ } else if (exp == 0x7fff)
+ tag |= 2; /* Infinity or NaN */
+ } else
+ tag |= 3; /* Empty */
+ st = (st - 1) & 7;
+ }
+ s87->s87_tw = tag;
}
static void
diff --git a/tests/lib/libc/sys/t_ptrace_x86_wait.h
b/tests/lib/libc/sys/t_ptrace_x86_wait.h
index d7e93fde55a3..6067066a36c1 100644
--- a/tests/lib/libc/sys/t_ptrace_x86_wait.h
+++ b/tests/lib/libc/sys/t_ptrace_x86_wait.h
@@ -3367,10 +3367,8 @@ x86_register_test(enum x86_test_regset regset, enum
x86_test_registers regs,
expected_fpu.cw);
ATF_CHECK_EQ(fpr.fstate.s87_sw,
expected_fpu.sw);
-#if 0 /* TODO: translation from FXSAVE is broken */
ATF_CHECK_EQ(fpr.fstate.s87_tw,
expected_fpu.tw);
-#endif
ATF_CHECK_EQ(fpr.fstate.s87_opcode,
expected_fpu.opcode);
ATF_CHECK_EQ(fpr.fstate.s87_ip.fa_32.fa_off,
--
2.28.0
