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tcg: Avoid undefined behaviour patching code at unaligned addresses

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To avoid C undefined behaviour when patching generated code,
provide wrappers tcg_patch8/16/32/64 which use the usual memcpy
trick, and use them in the i386 backend.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Peter Maydell 2014-03-28 15:29:48 +00:00 • committed by Richard Henderson
parent 4387345a96
commit 5c53bb8121
2 changed files with 26 additions and 6 deletions
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20
tcg/tcg.c
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@ -122,6 +122,11 @@ static inline void tcg_out8(TCGContext *s, uint8_t v)
*s->code_ptr++ = v;
}
static inline void tcg_patch8(uint8_t *p, uint8_t v)
{
memcpy(p, &v, sizeof(v));
}
static inline void tcg_out16(TCGContext *s, uint16_t v)
{
uint8_t *p = s->code_ptr;
@ -129,6 +134,11 @@ static inline void tcg_out16(TCGContext *s, uint16_t v)
s->code_ptr = p + 2;
}
static inline void tcg_patch16(uint8_t *p, uint16_t v)
{
memcpy(p, &v, sizeof(v));
}
static inline void tcg_out32(TCGContext *s, uint32_t v)
{
uint8_t *p = s->code_ptr;
@ -136,6 +146,11 @@ static inline void tcg_out32(TCGContext *s, uint32_t v)
s->code_ptr = p + 4;
}
static inline void tcg_patch32(uint8_t *p, uint32_t v)
{
memcpy(p, &v, sizeof(v));
}
static inline void tcg_out64(TCGContext *s, uint64_t v)
{
uint8_t *p = s->code_ptr;
@ -143,6 +158,11 @@ static inline void tcg_out64(TCGContext *s, uint64_t v)
s->code_ptr = p + 8;
}
static inline void tcg_patch64(uint8_t *p, uint64_t v)
{
memcpy(p, &v, sizeof(v));
}
/* label relocation processing */
static void tcg_out_reloc(TCGContext *s, uint8_t *code_ptr, int type,