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target/i386: implement SYSCALL/SYSRET in 32-bit emulators

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AMD supports both 32-bit and 64-bit SYSCALL/SYSRET, but the TCG only
exposes it for 64-bit targets.  For system emulation just reuse the
helper; for user-mode emulation the ABI is the same as "int $80".

The BSDs does not support any fast system call mechanism in 32-bit
mode so add to bsd-user the same stub that FreeBSD has for 64-bit
compatibility mode.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2023-06-17 01:01:29 +02:00
parent 6750485bf4
commit 63fd8ef080
8 changed files with 20 additions and 17 deletions
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7
target/i386/tcg/seg_helper.c
View file

@ -977,6 +977,7 @@ static void do_interrupt64(CPUX86State *env, int intno, int is_int,
e2);
env->eip = offset;
}
#endif /* TARGET_X86_64 */
void helper_sysret(CPUX86State *env, int dflag)
{
@ -990,6 +991,7 @@ void helper_sysret(CPUX86State *env, int dflag)
raise_exception_err_ra(env, EXCP0D_GPF, 0, GETPC());
}
selector = (env->star >> 48) & 0xffff;
#ifdef TARGET_X86_64
if (env->hflags & HF_LMA_MASK) {
cpu_load_eflags(env, (uint32_t)(env->regs[11]), TF_MASK | AC_MASK
| ID_MASK | IF_MASK | IOPL_MASK | VM_MASK | RF_MASK |
@ -1015,7 +1017,9 @@ void helper_sysret(CPUX86State *env, int dflag)
DESC_G_MASK | DESC_B_MASK | DESC_P_MASK |
DESC_S_MASK | (3 << DESC_DPL_SHIFT) |
DESC_W_MASK | DESC_A_MASK);
} else {
} else
#endif
{
env->eflags |= IF_MASK;
cpu_x86_load_seg_cache(env, R_CS, selector | 3,
0, 0xffffffff,
@ -1030,7 +1034,6 @@ void helper_sysret(CPUX86State *env, int dflag)
DESC_W_MASK | DESC_A_MASK);
}
}
#endif /* TARGET_X86_64 */
/* real mode interrupt */
static void do_interrupt_real(CPUX86State *env, int intno, int is_int,