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Add a sysctl to get the vm protections for the stack of the current process.

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On architectures with a non-executable stack, eg sparc64, this is used by
libgcc to determine at runtime if its necessary to enable execute permissions
on a region of the stack which will be used to execute code, allowing the
call to mprotect to be avoided if the kernel is configured to map the stack
executable.
This commit is contained in:
jake 2003-01-04 07:54:23 +00:00
parent 30246458a2
commit 94ee5f0ac5
1 changed files with 14 additions and 0 deletions
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14
sys/kern/kern_exec.c
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@ -76,6 +76,7 @@ static MALLOC_DEFINE(M_ATEXEC, "atexec", "atexec callback");
static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS);
static int kern_execve(struct thread *td, char *fname, char **argv,
char **envv, struct mac *mac_p);
@ -98,6 +99,9 @@ SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD,
SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD,
NULL, 0, sysctl_kern_usrstack, "LU", "");
SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD,
NULL, 0, sysctl_kern_stackprot, "I", "");
u_long ps_arg_cache_limit = PAGE_SIZE / 16;
SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW,
&ps_arg_cache_limit, 0, "");
@ -131,6 +135,16 @@ sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
sizeof(p->p_sysent->sv_usrstack)));
}
static int
sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)
{
struct proc *p;
p = curproc;
return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot,
sizeof(p->p_sysent->sv_stackprot)));
}
/*
* Each of the items is a pointer to a `const struct execsw', hence the
* double pointer here.