| Message ID | 20180612005145.3375-7-richard.henderson@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | linux-user: Split do_syscall | expand |
On 06/11/2018 09:51 PM, Richard Henderson wrote: > There was supposed to be a single point of return for do_syscall > so that tracing works properly. However, there are a few bugs > in that area. It is significantly simpler to simply split out > an inner function to enforce this. > > Reviewed-by: Laurent Vivier <laurent@vivier.eu> > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > --- > linux-user/syscall.c | 77 +++++++++++++++++++++++++++----------------- > 1 file changed, 48 insertions(+), 29 deletions(-) > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index c212149245..ec3bc1cbe5 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -7947,13 +7947,15 @@ static int host_to_target_cpu_mask(const unsigned long *host_mask, > return 0; > } > > -/* do_syscall() should always have a single exit point at the end so > - that actions, such as logging of syscall results, can be performed. > - All errnos that do_syscall() returns must be -TARGET_<errcode>. */ > -abi_long do_syscall(void *cpu_env, int num, abi_long arg1, > - abi_long arg2, abi_long arg3, abi_long arg4, > - abi_long arg5, abi_long arg6, abi_long arg7, > - abi_long arg8) > +/* This is an internal helper for do_syscall so that it is easier > + * to have a single return point, so that actions, such as logging > + * of syscall results, can be performed. > + * All errnos that do_syscall() returns must be -TARGET_<errcode>. > + */ > +static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1, > + abi_long arg2, abi_long arg3, abi_long arg4, > + abi_long arg5, abi_long arg6, abi_long arg7, > + abi_long arg8) > { > CPUState *cpu = ENV_GET_CPU(cpu_env); > abi_long ret; > @@ -7961,25 +7963,6 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, > struct statfs stfs; > void *p; > > -#if defined(DEBUG_ERESTARTSYS) > - /* Debug-only code for exercising the syscall-restart code paths > - * in the per-architecture cpu main loops: restart every syscall > - * the guest makes once before letting it through. > - */ > - { > - static int flag; > - > - flag = !flag; > - if (flag) { > - return -TARGET_ERESTARTSYS; > - } > - } > -#endif > - > - trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8); > - if(do_strace) > - print_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6); > - > switch(num) { > case TARGET_NR_exit: > /* In old applications this may be used to implement _exit(2). > @@ -12765,11 +12748,47 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, > break; > } > fail: > - if(do_strace) > - print_syscall_ret(num, ret); > - trace_guest_user_syscall_ret(cpu, num, ret); > return ret; > efault: > ret = -TARGET_EFAULT; > goto fail; > } > + > +abi_long do_syscall(void *cpu_env, int num, abi_long arg1, > + abi_long arg2, abi_long arg3, abi_long arg4, > + abi_long arg5, abi_long arg6, abi_long arg7, > + abi_long arg8) > +{ > + CPUState *cpu = ENV_GET_CPU(cpu_env); > + abi_long ret; > + > +#ifdef DEBUG_ERESTARTSYS > + /* Debug-only code for exercising the syscall-restart code paths > + * in the per-architecture cpu main loops: restart every syscall > + * the guest makes once before letting it through. > + */ > + { > + static bool flag; > + flag = !flag; > + if (flag) { > + return -TARGET_ERESTARTSYS; > + } > + } > +#endif > + > + trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4, > + arg5, arg6, arg7, arg8); > + > + if (unlikely(do_strace)) { > + print_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6); > + ret = do_syscall1(cpu_env, num, arg1, arg2, arg3, arg4, > + arg5, arg6, arg7, arg8); > + print_syscall_ret(num, ret); > + } else { > + ret = do_syscall1(cpu_env, num, arg1, arg2, arg3, arg4, > + arg5, arg6, arg7, arg8); > + } > + > + trace_guest_user_syscall_ret(cpu, num, ret); > + return ret; > +} >
diff --git a/linux-user/syscall.c b/linux-user/syscall.c index c212149245..ec3bc1cbe5 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -7947,13 +7947,15 @@ static int host_to_target_cpu_mask(const unsigned long *host_mask, return 0; } -/* do_syscall() should always have a single exit point at the end so - that actions, such as logging of syscall results, can be performed. - All errnos that do_syscall() returns must be -TARGET_<errcode>. */ -abi_long do_syscall(void *cpu_env, int num, abi_long arg1, - abi_long arg2, abi_long arg3, abi_long arg4, - abi_long arg5, abi_long arg6, abi_long arg7, - abi_long arg8) +/* This is an internal helper for do_syscall so that it is easier + * to have a single return point, so that actions, such as logging + * of syscall results, can be performed. + * All errnos that do_syscall() returns must be -TARGET_<errcode>. + */ +static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1, + abi_long arg2, abi_long arg3, abi_long arg4, + abi_long arg5, abi_long arg6, abi_long arg7, + abi_long arg8) { CPUState *cpu = ENV_GET_CPU(cpu_env); abi_long ret; @@ -7961,25 +7963,6 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, struct statfs stfs; void *p; -#if defined(DEBUG_ERESTARTSYS) - /* Debug-only code for exercising the syscall-restart code paths - * in the per-architecture cpu main loops: restart every syscall - * the guest makes once before letting it through. - */ - { - static int flag; - - flag = !flag; - if (flag) { - return -TARGET_ERESTARTSYS; - } - } -#endif - - trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8); - if(do_strace) - print_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6); - switch(num) { case TARGET_NR_exit: /* In old applications this may be used to implement _exit(2). @@ -12765,11 +12748,47 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, break; } fail: - if(do_strace) - print_syscall_ret(num, ret); - trace_guest_user_syscall_ret(cpu, num, ret); return ret; efault: ret = -TARGET_EFAULT; goto fail; } + +abi_long do_syscall(void *cpu_env, int num, abi_long arg1, + abi_long arg2, abi_long arg3, abi_long arg4, + abi_long arg5, abi_long arg6, abi_long arg7, + abi_long arg8) +{ + CPUState *cpu = ENV_GET_CPU(cpu_env); + abi_long ret; + +#ifdef DEBUG_ERESTARTSYS + /* Debug-only code for exercising the syscall-restart code paths + * in the per-architecture cpu main loops: restart every syscall + * the guest makes once before letting it through. + */ + { + static bool flag; + flag = !flag; + if (flag) { + return -TARGET_ERESTARTSYS; + } + } +#endif + + trace_guest_user_syscall(cpu, num, arg1, arg2, arg3, arg4, + arg5, arg6, arg7, arg8); + + if (unlikely(do_strace)) { + print_syscall(num, arg1, arg2, arg3, arg4, arg5, arg6); + ret = do_syscall1(cpu_env, num, arg1, arg2, arg3, arg4, + arg5, arg6, arg7, arg8); + print_syscall_ret(num, ret); + } else { + ret = do_syscall1(cpu_env, num, arg1, arg2, arg3, arg4, + arg5, arg6, arg7, arg8); + } + + trace_guest_user_syscall_ret(cpu, num, ret); + return ret; +}