From d98ec57128628b81fcd32269a92742a037b7f713 Mon Sep 17 00:00:00 2001
From: Kimplul <kimi.h.kuparinen@gmail.com>
Date: Sun, 26 Dec 2021 17:50:11 +0200
Subject: First useful jump to userspace!

---
 common/elf.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 78 insertions(+), 7 deletions(-)

(limited to 'common/elf.c')

diff --git a/common/elf.c b/common/elf.c
index c6a37e0..c73d56c 100644
--- a/common/elf.c
+++ b/common/elf.c
@@ -1,12 +1,83 @@
 #include <apos/elf.h>
 #include <apos/vmem.h>
+#include <apos/bytes.h>
+#include <apos/string.h>
 
-vm_t bin_entry(vm_t bin)
+static void __map_exec(struct tcb *t, vm_t bin, uint8_t ei_c, vm_t phstart, size_t phnum, size_t phsize)
 {
-	struct elf_header *e = (struct elf_header *)bin;
-	/* TODO: check that address points to a valid ELF executable */
-	/* oh yeah, this only works for DYN objects, fuck */
-	/* eh, fuck it, I'll fix this later, today has been a decently
-	 * productive day as is */
-	return ((vm_t)e->e_entry) + bin;
+	/* TODO: take alignment into consideration? */
+	vm_t runner = phstart;
+	for(size_t i = 0; i < phnum; ++i, runner += phsize){
+		if(program_header_prop(ei_c, runner, p_type) != PT_LOAD)
+			continue;
+
+		vm_t va = program_header_prop(ei_c, runner, p_vaddr);
+		size_t vsz = program_header_prop(ei_c, runner, p_memsz);
+
+		vm_t start = 0;
+		if(!(start = alloc_fixed_region(&t->sp_r, va, vsz, 0)))
+				return; /* out of memory or something */
+
+		uint8_t vflags = VM_V | VM_U;
+		uint8_t bflags = program_header_prop(ei_c, runner, p_flags);
+		if(bflags & PF_X)
+			vflags |= VM_X;
+
+		if(bflags & PF_W)
+			vflags |= VM_W;
+
+		if(bflags & PF_R)
+			vflags |= VM_R;
+
+		map_fill_region(t->b_r, start, vsz, VM_V | VM_X | VM_R | VM_W | VM_U);
+
+		vm_t vo = bin + program_header_prop(ei_c, runner, p_offset);
+		vm_t vfz = program_header_prop(ei_c, runner, p_filesz);
+		memcpy((void *)va, (void *)vo, vfz);
+
+		/* skip while testing
+		pm_t paddr = 0;
+		stat_vmem(t->b_r, va, &paddr, 0, 0);
+		mod_vmem(t->b_r, va, paddr, vflags);
+		*/
+	}
+}
+
+static vm_t __map_dyn(struct tcb *t, vm_t bin, uint8_t ei_c, vm_t phstart, size_t phnum, size_t phsize)
+{
+	/* TODO */
+}
+
+static vm_t __prepare_proc(struct tcb *t, uint8_t ei_c, vm_t elf)
+{
+	short e_type = elf_header_prop(ei_c, elf, e_type);
+	if(e_type != ET_DYN && e_type != ET_EXEC)
+		return 0;
+
+	vm_t phstart = ptradd(elf, elf_header_prop(ei_c, elf, e_phoff));
+	size_t phnum = elf_header_prop(ei_c, elf, e_phnum);
+	size_t phsize = elf_header_prop(ei_c, elf, e_phentsize);
+
+	vm_t entry = elf_header_prop(ei_c, elf, e_entry);
+	if(e_type == ET_EXEC){
+		__map_exec(t, elf, ei_c, phstart, phnum, phsize);
+		return entry;
+	} else {
+		vm_t o = __map_dyn(t, elf, ei_c, phstart, phnum, phsize);
+		return o + entry;
+	}
+}
+
+/* sets up all memory regions etc, returns the entry address */
+vm_t prepare_proc(struct tcb *t, vm_t p)
+{
+	struct elf_ident *i = (struct elf_ident *)p;
+	if(i->ei_magic != cpu_to_be32(EI_MAGIC))
+		return 0;
+
+	if(i->ei_class != ELFCLASS32 && i->ei_class != ELFCLASS64)
+			return 0;
+
+	/* more sanity checks? */
+	return __prepare_proc(t, i->ei_class, p);
 }
-- 
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