Richard Henderson <richard.hender...@linaro.org> writes:
> Notice the magic page during translate, much like we already
> do for the arm32 commpage. At runtime, raise an exception to
> return cpu_loop for emulation.
>
> Reviewed-by: Paolo Bonzini <pbonz...@redhat.com>
> Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
> ---
> target/i386/cpu.h | 1 +
> linux-user/i386/cpu_loop.c | 105 +++++++++++++++++++++++++++++++++++++
> target/i386/translate.c | 16 +++++-
> 3 files changed, 121 insertions(+), 1 deletion(-)
>
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 164d038d1f..3fb2d2a986 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -1000,6 +1000,7 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS];
>
> #define EXCP_VMEXIT 0x100 /* only for system emulation */
> #define EXCP_SYSCALL 0x101 /* only for user emulation */
> +#define EXCP_VSYSCALL 0x102 /* only for user emulation */
>
> /* i386-specific interrupt pending bits. */
> #define CPU_INTERRUPT_POLL CPU_INTERRUPT_TGT_EXT_1
> diff --git a/linux-user/i386/cpu_loop.c b/linux-user/i386/cpu_loop.c
> index e217cca5ee..f9bf6cec27 100644
> --- a/linux-user/i386/cpu_loop.c
> +++ b/linux-user/i386/cpu_loop.c
> @@ -92,6 +92,106 @@ static void gen_signal(CPUX86State *env, int sig, int
> code, abi_ptr addr)
> queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
> }
>
> +#ifdef TARGET_X86_64
> +static bool write_ok_or_segv(CPUX86State *env, abi_ptr addr, size_t len)
> +{
> + /*
> + * For all the vsyscalls, NULL means "don't write anything" not
> + * "write it at address 0".
> + */
> + if (addr == 0 || access_ok(VERIFY_WRITE, addr, len)) {
> + return true;
> + }
> +
> + env->error_code = PG_ERROR_W_MASK | PG_ERROR_U_MASK;
> + gen_signal(env, TARGET_SIGSEGV, TARGET_SEGV_MAPERR, addr);
> + return false;
> +}
> +
> +/*
> + * Since v3.1, the kernel traps and emulates the vsyscall page.
> + * Entry points other than the official generate SIGSEGV.
> + */
> +static void emulate_vsyscall(CPUX86State *env)
> +{
> + int syscall;
> + abi_ulong ret;
> + uint64_t caller;
> +
> + /*
> + * Validate the entry point. We have already validated the page
> + * during translation, now verify the offset.
> + */
> + switch (env->eip & ~TARGET_PAGE_MASK) {
> + case 0x000:
> + syscall = TARGET_NR_gettimeofday;
> + break;
> + case 0x400:
> + syscall = TARGET_NR_time;
> + break;
> + case 0x800:
> + syscall = TARGET_NR_getcpu;
> + break;
> + default:
> + sigsegv:
this label looks a little extraneous.
Otherwise:
Reviewed-by: Alex Bennée <alex.ben...@linaro.org>
--
Alex Bennée
