From: Elad Lahav <elad_lahav@xxxxxxxxxxxxxxxxxxxxx>
Date: Mon, 09 Mar 2009 12:28:31 -0400
> According to the man page (which, I believe, conforms to the POSIX standard), the third argument in a signal handler should be a pointer to a ucontext structure (assuming the SA_SIGINFO flag was passed to sigaction). However, under Sparc64, the kernel passes a pointer to a sigcontext structure (see line 472 in arch/sparc64/kernel/signal.c). This incompatibility should be either fixed or documented.
It's passing a siginfo_t as both the second and third argument:
struct rt_signal_frame {
struct sparc_stackf ss;
siginfo_t info;
...
static inline void
setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
int signo, sigset_t *oldset, siginfo_t *info)
{
...
struct rt_signal_frame __user *sf;
...
regs->u_regs[UREG_I0] = signo;
regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
/* The sigcontext is passed in this way because of how it
* is defined in GLIBC's /usr/include/bits/sigcontext.h
* for sparc64. It includes the 128 bytes of siginfo_t.
*/
regs->u_regs[UREG_I2] = (unsigned long) &sf->info;
The sigaction man page says:
struct sigaction {
void (*sa_handler)(int);
void (*sa_sigaction)(int, siginfo_t *, void *);
sigset_t sa_mask;
int sa_flags;
void (*sa_restorer)(void);
}
The actual type of the third argument is architecture independant,
that is why it is defined as "void *" rather than a specific type.
Which is effectively a "sigcontext" which on sparc64 is defined as a
structure containing a siginfo_t then the register information. See
/usr/include/bits/sigcontext.h
Yes it says ucontext_t and sparc is the lone-wolf out here.
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