libk  Artifact [e98ef79662]

Artifact e98ef79662b3a8becb3950ba82f139ac612b729926aedc741351b53608065256:

  • File mod/kmem/heapao.fn.c — part of check-in [e50a476efe] at 2019-08-22 02:52:20 on branch trunk — removed sneaky segfault in x86-64 syscall fn where %r8 (the register that contains the pointer to the syscall arguments from the C syscall wrapper, which need to be copied into the correct registers before the kernel is invoked) gets overwritten if the syscall valency > 5, because of overlapping ccall and syscall ABI argument registers - r8 is clobbered by argument 5 and any further attempts to use it as a ptr segfault at best. also modified the report function so that it immediate cancels compilation if a sub-process reports failure. changed allocator function signatures so they can return a condition code if the kernel reports an error; updated example code so it compiles and runs without fault. (user: lexi, size: 500) [annotate] [blame] [check-ins using]

#include <k/core.h>
#include <k/mem.h>
/* heapao.fn.c - kmheapao() "allocate heap object"
 * ~ lexi hale <lexi@hale.su>
 * kmheapao() allocates a region in heap memory
 * and returns a kmptr struct referencing that
 * newly allocated region.
 */

kmcond kmheapao(kmptr* where, sz size) {
	void* ptr;
	kmcond e = kmheapa(&ptr, size);
	if (e != kmcond_ok) return e;
	kmptr p = {
		.kind = (ptr != null ? kmkind_heap : kmkind_fail),
		.ref = ptr,
		.shred = false,
	};
	*where = p;
	return kmcond_ok;
}