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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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9
linux-user/i386/cpu_loop.c
View file

@ -211,6 +211,9 @@ void cpu_loop(CPUX86State *env)
switch(trapnr) {
case 0x80:
#ifndef TARGET_X86_64
case EXCP_SYSCALL:
#endif
/* linux syscall from int $0x80 */
ret = do_syscall(env,
env->regs[R_EAX],
@ -227,9 +230,9 @@ void cpu_loop(CPUX86State *env)
env->regs[R_EAX] = ret;
}
break;
#ifndef TARGET_ABI32
#ifdef TARGET_X86_64
case EXCP_SYSCALL:
/* linux syscall from syscall instruction */
/* linux syscall from syscall instruction. */
ret = do_syscall(env,
env->regs[R_EAX],
env->regs[R_EDI],
@ -245,8 +248,6 @@ void cpu_loop(CPUX86State *env)
env->regs[R_EAX] = ret;
}
break;
#endif
#ifdef TARGET_X86_64
case EXCP_VSYSCALL:
emulate_vsyscall(env);
break;