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target/sh4: Handle user-space atomics

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For uniprocessors, SH4 uses optimistic restartable atomic sequences.
Upon an interrupt, a real kernel would simply notice magic values in
the registers and reset the PC to the start of the sequence.

For QEMU, we cannot do this in quite the same way.  Instead, we notice
the normal start of such a sequence (mov #-x,r15), and start a new TB
that can be executed under cpu_exec_step_atomic.

Reported-by: Bruno Haible  <bruno@clisp.org>
LP: https://bugs.launchpad.net/bugs/1701971
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Message-Id: <20170718200255.31647-7-rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Richard Henderson 2017-07-18 10:02:31 -10:00 • committed by Aurelien Jarno
parent 1516184d8e
commit 4bfa602bc2
4 changed files with 149 additions and 16 deletions
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18
target/sh4/cpu.h
View file

@ -98,7 +98,18 @@
#define TB_FLAG_PENDING_MOVCA (1 << 3)
#define TB_FLAG_ENVFLAGS_MASK DELAY_SLOT_MASK
#define GUSA_SHIFT 4
#ifdef CONFIG_USER_ONLY
#define GUSA_EXCLUSIVE (1 << 12)
#define GUSA_MASK ((0xff << GUSA_SHIFT) | GUSA_EXCLUSIVE)
#else
/* Provide dummy versions of the above to allow tests against tbflags
to be elided while avoiding ifdefs. */
#define GUSA_EXCLUSIVE 0
#define GUSA_MASK 0
#endif
#define TB_FLAG_ENVFLAGS_MASK (DELAY_SLOT_MASK | GUSA_MASK)
typedef struct tlb_t {
uint32_t vpn; /* virtual page number */
@ -389,8 +400,9 @@ static inline void cpu_get_tb_cpu_state(CPUSH4State *env, target_ulong *pc,
target_ulong *cs_base, uint32_t *flags)
{
*pc = env->pc;
*cs_base = 0;
*flags = env->flags /* Bits 0-2 */
/* For a gUSA region, notice the end of the region. */
*cs_base = env->flags & GUSA_MASK ? env->gregs[0] : 0;
*flags = env->flags /* TB_FLAG_ENVFLAGS_MASK: bits 0-2, 4-12 */
| (env->fpscr & (FPSCR_FR | FPSCR_SZ | FPSCR_PR)) /* Bits 19-21 */
| (env->sr & ((1u << SR_MD) | (1u << SR_RB))) /* Bits 29-30 */
| (env->sr & (1u << SR_FD)) /* Bit 15 */