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target/i386: Move helper_check_io to sysemu

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The we never allow i/o from user-only, and the tss check
that helper_check_io does will always fail.  Use an ifdef
within gen_check_io and return false, indicating that an
exception is known to be raised.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210514151342.384376-50-richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2021-05-14 10:13:41 -05:00
parent e497803556
commit d76b9c6f07
4 changed files with 40 additions and 30 deletions
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29
target/i386/tcg/sysemu/seg_helper.c
View file

@ -23,6 +23,7 @@
#include "exec/helper-proto.h"
#include "exec/cpu_ldst.h"
#include "tcg/helper-tcg.h"
#include "../seg_helper.h"
#ifdef TARGET_X86_64
void helper_syscall(CPUX86State *env, int next_eip_addend)
@ -123,3 +124,31 @@ void x86_cpu_do_interrupt(CPUState *cs)
env->old_exception = -1;
}
}
/* check if Port I/O is allowed in TSS */
void helper_check_io(CPUX86State *env, uint32_t addr, uint32_t size)
{
uintptr_t retaddr = GETPC();
uint32_t io_offset, val, mask;
/* TSS must be a valid 32 bit one */
if (!(env->tr.flags & DESC_P_MASK) ||
((env->tr.flags >> DESC_TYPE_SHIFT) & 0xf) != 9 ||
env->tr.limit < 103) {
goto fail;
}
io_offset = cpu_lduw_kernel_ra(env, env->tr.base + 0x66, retaddr);
io_offset += (addr >> 3);
/* Note: the check needs two bytes */
if ((io_offset + 1) > env->tr.limit) {
goto fail;
}
val = cpu_lduw_kernel_ra(env, env->tr.base + io_offset, retaddr);
val >>= (addr & 7);
mask = (1 << size) - 1;
/* all bits must be zero to allow the I/O */
if ((val & mask) != 0) {
fail:
raise_exception_err_ra(env, EXCP0D_GPF, 0, retaddr);
}
}