On Mon, Sep 27, 2021 at 02:42:48PM +0800, Huacai Chen wrote:
> +/*
> + * Does the process account for user or for system time?
> + */
> +#define user_mode(regs) (((regs)->csr_prmd & PLV_MASK) == PLV_USER)
> +
> +static inline int is_syscall_success(struct pt_regs *regs)
> +{
> + return !regs->regs[7];
> +}
>
> +static inline long regs_return_value(struct pt_regs *regs)
> +{
> + if (is_syscall_success(regs) || !user_mode(regs))
> + return regs->regs[4];
> + else
> + return -regs->regs[4];
> +}
Huh??? That looks like you've copied those from MIPS, but on MIPS we have
things like
li t0, -EMAXERRNO - 1 # error?
sltu t0, t0, v0
sd t0, PT_R7(sp) # set error flag
beqz t0, 1f
ld t1, PT_R2(sp) # syscall number
dnegu v0 # error
sd t1, PT_R0(sp) # save it for syscall restarting
1: sd v0, PT_R2(sp) # result
right after the call of sys_...(), along with the restart logics
looking like
if (regs->regs[0]) {
switch(regs->regs[2]) {
case ERESTART_RESTARTBLOCK:
case ERESTARTNOHAND:
IOW, syscall return values from -EMAXERRNO to -1 are negated, with
regs[7] set accordingly. Nothing of that sort is done in your
patchset after syscall, and if it had been, your restart logics in
signal handling would've been wrong anyway.
What's going on there?
