Because the BTX mini-kernel now uses flat memory mode and clients

are no longer limited to a virtual address space of 16 megabytes,
only mask high two bits of a virtual address.  This allows to load
larger kernels (up to 1 gigabyte).  Not masking addresses at all
was a bad idea on machines with less than >3G of memory -- kernels
are linked at 0xc0xxxxxx, and that would attempt to load a kernel
at above 3G.  By masking only two highest bits we stay within the
safe limits while still allowing to boot larger kernels.

(This is a safer reimplmentation of sys/boot/i386/boot2/boot.2.c
rev. 1.71.)

Prodded by:	jhb
Tested by:	nyan (pc98)

5 files changed, 10 insertions, 10 deletions

diff --git a/sys/boot/common/load_elf.c b/sys/boot/common/load_elf.c
index cd983a9..be8f881 100644
--- a/sys/boot/common/load_elf.c
+++ b/sys/boot/common/load_elf.c
@@ -263,7 +263,7 @@ __elfN(loadimage)(struct preloaded_file *fp, elf_file_t ef, u_int64_t off)
 #if __ELF_WORD_SIZE == 64
 	off = - (off & 0xffffffffff000000ull);/* x86_64 relocates after locore */
 #else
-	off = - (off & 0xff000000u);	/* i386 relocates after locore */
+	off = - (off & 0xc0000000u);	/* i386 relocates after locore */
 #endif
 #else
 	off = 0;		/* other archs use direct mapped kernels */
diff --git a/sys/boot/i386/boot2/boot2.c b/sys/boot/i386/boot2/boot2.c
index df3fe81..b07c9ed 100644
--- a/sys/boot/i386/boot2/boot2.c
+++ b/sys/boot/i386/boot2/boot2.c
@@ -334,7 +334,7 @@ load(void)
 	return;
     }
     if (fmt == 0) {
-	addr = hdr.ex.a_entry & 0xffffff;
+	addr = hdr.ex.a_entry & 0x3fffffff;
 	p = PTOV(addr);
 	fs_off = PAGE_SIZE;
 	if (xfsread(ino, p, hdr.ex.a_text))
@@ -368,7 +368,7 @@ load(void)
 		j++;
 	}
 	for (i = 0; i < 2; i++) {
-	    p = PTOV(ep[i].p_paddr & 0xffffff);
+	    p = PTOV(ep[i].p_paddr & 0x3fffffff);
 	    fs_off = ep[i].p_offset;
 	    if (xfsread(ino, p, ep[i].p_filesz))
 		return;
@@ -389,7 +389,7 @@ load(void)
 		p += es[i].sh_size;
 	    }
 	}
-	addr = hdr.eh.e_entry & 0xffffff;
+	addr = hdr.eh.e_entry & 0x3fffffff;
     }
     bootinfo.bi_esymtab = VTOP(p);
     bootinfo.bi_kernelname = VTOP(kname);
diff --git a/sys/boot/i386/gptboot/gptboot.c b/sys/boot/i386/gptboot/gptboot.c
index df3fe81..b07c9ed 100644
--- a/sys/boot/i386/gptboot/gptboot.c
+++ b/sys/boot/i386/gptboot/gptboot.c
@@ -334,7 +334,7 @@ load(void)
 	return;
     }
     if (fmt == 0) {
-	addr = hdr.ex.a_entry & 0xffffff;
+	addr = hdr.ex.a_entry & 0x3fffffff;
 	p = PTOV(addr);
 	fs_off = PAGE_SIZE;
 	if (xfsread(ino, p, hdr.ex.a_text))
@@ -368,7 +368,7 @@ load(void)
 		j++;
 	}
 	for (i = 0; i < 2; i++) {
-	    p = PTOV(ep[i].p_paddr & 0xffffff);
+	    p = PTOV(ep[i].p_paddr & 0x3fffffff);
 	    fs_off = ep[i].p_offset;
 	    if (xfsread(ino, p, ep[i].p_filesz))
 		return;
@@ -389,7 +389,7 @@ load(void)
 		p += es[i].sh_size;
 	    }
 	}
-	addr = hdr.eh.e_entry & 0xffffff;
+	addr = hdr.eh.e_entry & 0x3fffffff;
     }
     bootinfo.bi_esymtab = VTOP(p);
     bootinfo.bi_kernelname = VTOP(kname);
diff --git a/sys/boot/i386/libi386/elf32_freebsd.c b/sys/boot/i386/libi386/elf32_freebsd.c
index 5f66622..c1363bc 100644
--- a/sys/boot/i386/libi386/elf32_freebsd.c
+++ b/sys/boot/i386/libi386/elf32_freebsd.c
@@ -65,7 +65,7 @@ elf32_exec(struct preloaded_file *fp)
     err = bi_load32(fp->f_args, &boothowto, &bootdev, &bootinfop, &modulep, &kernend);
     if (err != 0)
 	return(err);
-    entry = ehdr->e_entry & 0xffffff;
+    entry = ehdr->e_entry & 0x3fffffff;
 
 #ifdef DEBUG
     printf("Start @ 0x%lx ...\n", entry);
diff --git a/sys/boot/pc98/boot2/boot.c b/sys/boot/pc98/boot2/boot.c
index feccc7e..96dfb72 100644
--- a/sys/boot/pc98/boot2/boot.c
+++ b/sys/boot/pc98/boot2/boot.c
@@ -199,9 +199,9 @@ loadprog(void)
 	/*
 	 * We assume that the entry address is the same as the lowest text
 	 * address and that the kernel startup code handles relocation by
-	 * this address rounded down to a multiple of 16M.
+	 * this address rounded down to a multiple of 1G.
 	 */
-	startaddr = head.a_entry & 0x00FFFFFF;
+	startaddr = head.a_entry & 0x3FFFFFFF;
 	addr =  startaddr;
 	printf("Booting %d:%s(%d,%c)%s @ 0x%x\n"
 			, dosdev & 0x0f