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tcg/sparc: Zero extend data argument to store helpers

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The C store helper functions take the data argument as a uint8_t,
uint16_t, etc depending on the store size. The SPARC calling
convention requires that data types smaller than the register
size must be extended by the caller. We weren't doing this,
which meant that if QEMU was compiled with optimizations enabled
we could end up storing incorrect values to guest memory.
(In particular the i386 guest BIOS would crash on startup.)

Add code to the trampolines that call the store helpers to
do the zero extension as required.

Backports commit 709a340d679d95a0c6cbb9b5f654498f04345b50 from qemu
This commit is contained in:
Peter Maydell 2018-03-02 14:24:18 -05:00 committed by Lioncash
parent e71c7b7819
commit 40718df109
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GPG Key ID: 4E3C3CC1031BA9C7
1 changed files with 26 additions and 1 deletions
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25
qemu/tcg/sparc/tcg-target.inc.c
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@ -845,6 +845,29 @@ static void tcg_out_mb(TCGContext *s, TCGArg a0)
static tcg_insn_unit *qemu_ld_trampoline[16];
static tcg_insn_unit *qemu_st_trampoline[16];
static void emit_extend(TCGContext *s, TCGReg r, int op)
{
/* Emit zero extend of 8, 16 or 32 bit data as
* required by the MO_* value op; do nothing for 64 bit.
*/
switch (op & MO_SIZE) {
case MO_8:
tcg_out_arithi(s, r, r, 0xff, ARITH_AND);
break;
case MO_16:
tcg_out_arithi(s, r, r, 16, SHIFT_SLL);
tcg_out_arithi(s, r, r, 16, SHIFT_SRL);
break;
case MO_32:
if (SPARC64) {
tcg_out_arith(s, r, r, 0, SHIFT_SRL);
}
break;
case MO_64:
break;
}
}
static void build_trampolines(TCGContext *s)
{
static void * const qemu_ld_helpers[16] = {
@ -912,6 +935,7 @@ static void build_trampolines(TCGContext *s)
qemu_st_trampoline[i] = s->code_ptr;
if (SPARC64) {
emit_extend(s, TCG_REG_O2, i);
ra = TCG_REG_O4;
} else {
ra = TCG_REG_O1;
@ -927,6 +951,7 @@ static void build_trampolines(TCGContext *s)
tcg_out_arithi(s, ra, ra + 1, 32, SHIFT_SRLX);
ra += 2;
} else {
emit_extend(s, ra, i);
ra += 1;
}
/* Skip the oi argument. */