Le 27/01/2025 à 12:44, Dmitry V. Levin a écrit :
On Mon, Jan 27, 2025 at 12:36:53PM +0100, Christophe Leroy wrote:
Le 27/01/2025 à 12:20, Dmitry V. Levin a écrit :
On Thu, Jan 23, 2025 at 11:07:21PM +0100, Christophe Leroy wrote:
[...]
To add a bit more to the confusion,
Looks like there is no end to it:
static inline long regs_return_value(struct pt_regs *regs)
{
if (trap_is_scv(regs))
return regs->gpr[3];
if (is_syscall_success(regs))
return regs->gpr[3];
else
return -regs->gpr[3];
}
static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
{
regs->gpr[3] = rc;
}
This doesn't look consistent, does it?
That regs_set_return_value() looks pretty similar to
syscall_get_return_value().
Yes, but here similarities end, and differences begin.
regs_set_return_value() documentation in asm-generic/syscall.h
explicitely says: This value is meaningless if syscall_get_error()
returned nonzero
Is it the same with regs_set_return_value(), only meaningfull where
there is no error ?
Did you mean syscall_set_return_value? No, it explicitly has two
arguments, "int error" and "long val", so it can be used to either
clear or set the error condition as specified by the caller.
Sorry, I mean syscall_get_return_value() here.
static inline long syscall_get_return_value(struct task_struct *task,
struct pt_regs *regs)
{
return regs->gpr[3];
}
Versus
static inline void regs_set_return_value(struct pt_regs *regs, unsigned
long rc)
{
regs->gpr[3] = rc;
}
By the way, why have two very similar APIs, one in syscall.h one in
ptrace.h ?
I have no polite answer to this, sorry.
