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util, pasta: Add do_clone() wrapper around __clone2() and clone()

Spotted in Debian's buildd logs: on ia64, clone(2) is not available:
the glibc wrapper is named __clone2() and it takes, additionally,
the size of the stack area passed by the caller.

Add a do_clone() wrapper handling the different cases, and also
taking care of pointing the child's stack in the middle of the
allocated area: on PA-RISC (hppa), handled by clone(), the stack
grows up, and on ia64 the stack grows down, but the register backing
store grows up -- and I think it might be actually used here.

Suggested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2022-11-13 02:21:47 +01:00
parent 7d8c2fb916
commit ab6f825889
3 changed files with 31 additions and 8 deletions

8
util.h
View file

@ -81,13 +81,15 @@
(((struct in_addr *)(a))->s_addr == ((struct in_addr *)b)->s_addr)
#define NS_FN_STACK_SIZE (RLIMIT_STACK_VAL * 1024 / 8)
int do_clone(int (*fn)(void *), char *stack_area, size_t stack_size, int flags,
void *arg);
#define NS_CALL(fn, arg) \
do { \
char ns_fn_stack[NS_FN_STACK_SIZE]; \
\
clone((fn), ns_fn_stack + sizeof(ns_fn_stack) / 2, \
CLONE_VM | CLONE_VFORK | CLONE_FILES | SIGCHLD, \
(void *)(arg)); \
do_clone((fn), ns_fn_stack, sizeof(ns_fn_stack), \
CLONE_VM | CLONE_VFORK | CLONE_FILES | SIGCHLD,\
(void *)(arg)); \
} while (0)
#if __BYTE_ORDER == __BIG_ENDIAN