kernel: use 64-bit virtual entry point for expanded header, document behaviour in a.out(6)
For 64-bit architectures, the a.out header has the HDR_MAGIC flag set in the magic and is expanded by 8 bytes containing the 64-bit virtual address of the programs entry point. While Exec.entry contains physical address for kernel images. Our sysexec() would always use Exec.entry, even for 64-bit a.out binaries, which worked because PADDR(entry) == entry for userspace pointers. This change fixes it, having the kernel use the 64-bit entry point and document the behaviour in the manpage.front
cinap_lenrek
parent
d168b89ab1
commit
c2297ce5c1
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@ -25,7 +25,7 @@ typedef struct Exec {
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long pcsz; /* size of pc/line number table */
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} Exec;
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#define HDR_MAGIC 0x00008000
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#define HDR_MAGIC 0x00008000 /* header expansion */
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#define _MAGIC(f, b) ((f)|((((4*(b))+0)*(b))+7))
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#define A_MAGIC _MAGIC(0, 8) /* 68020 */
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@ -62,7 +62,18 @@ The text segment consists of the header and the first
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bytes of the binary file.
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The
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.B entry
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field gives the virtual address of the entry point of the program.
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field gives the virtual address of the entry point of the program
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unless
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.B HDR_MAGIC
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flag is present in the
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.B magic
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field.
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In that case, the header is expanded
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by 8 bytes containing the 64-bit virtual address of the
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program entry point and the 32-bit
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.B entry
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field is reserved for physical kernel entry point.
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.PP
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The data segment starts at the first page-rounded virtual address
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after the text segment.
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It consists of the next
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@ -10,6 +10,8 @@ Block* allocb(int);
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int anyhigher(void);
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int anyready(void);
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Image* attachimage(int, Chan*, uintptr, ulong);
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ulong beswal(ulong);
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uvlong beswav(uvlong);
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int blocklen(Block*);
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void bootlinks(void);
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void cachedel(Image*, uintptr);
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@ -6,16 +6,6 @@
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#include "../port/error.h"
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#include "a.out.h"
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static ulong
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l2be(long l)
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{
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uchar *cp;
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cp = (uchar*)&l;
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return (cp[0]<<24) | (cp[1]<<16) | (cp[2]<<8) | cp[3];
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}
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static void
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readn(Chan *c, void *vp, long n)
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{
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@ -35,8 +25,11 @@ readn(Chan *c, void *vp, long n)
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void
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rebootcmd(int argc, char *argv[])
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{
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struct {
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Exec;
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uvlong hdr[1];
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} ehdr;
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Chan *c;
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Exec exec;
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ulong magic, text, rtext, entry, data, size, align;
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uchar *p;
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@ -49,11 +42,11 @@ rebootcmd(int argc, char *argv[])
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nexterror();
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}
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readn(c, &exec, sizeof(Exec));
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magic = l2be(exec.magic);
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entry = l2be(exec.entry);
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text = l2be(exec.text);
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data = l2be(exec.data);
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readn(c, &ehdr, sizeof(Exec));
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magic = beswal(ehdr.magic);
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entry = beswal(ehdr.entry);
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text = beswal(ehdr.text);
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data = beswal(ehdr.data);
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if(!(magic == AOUT_MAGIC)){
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switch(magic){
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@ -66,7 +59,7 @@ rebootcmd(int argc, char *argv[])
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}
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}
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if(magic & HDR_MAGIC)
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readn(c, &exec, 8);
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readn(c, ehdr.hdr, sizeof(ehdr.hdr));
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switch(magic){
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case R_MAGIC:
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@ -234,6 +234,8 @@ shargs(char *s, int n, char **ap)
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{
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int i;
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if(n <= 2 || s[0] != '#' || s[1] != '!')
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return -1;
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s += 2;
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n -= 2; /* skip #! */
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for(i=0;; i++){
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@ -261,27 +263,42 @@ shargs(char *s, int n, char **ap)
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return i;
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}
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static ulong
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l2be(long l)
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ulong
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beswal(ulong l)
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{
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uchar *cp;
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uchar *p;
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cp = (uchar*)&l;
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return (cp[0]<<24) | (cp[1]<<16) | (cp[2]<<8) | cp[3];
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p = (uchar*)&l;
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return (p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
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}
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uvlong
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beswav(uvlong v)
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{
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uchar *p;
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p = (uchar*)&v;
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return ((uvlong)p[0]<<56) | ((uvlong)p[1]<<48) | ((uvlong)p[2]<<40)
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| ((uvlong)p[3]<<32) | ((uvlong)p[4]<<24)
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| ((uvlong)p[5]<<16) | ((uvlong)p[6]<<8)
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| (uvlong)p[7];
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}
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uintptr
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sysexec(va_list list)
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{
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Exec exec;
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char line[sizeof(Exec)];
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struct {
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Exec;
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uvlong hdr[1];
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} ehdr;
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char line[sizeof(ehdr)];
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char *progarg[sizeof(line)/2+1];
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volatile char *args, *elem, *file0;
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char **argv, **argp, **argp0;
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char *a, *e, *charp, *file;
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int i, n, indir;
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ulong magic, ssize, nargs, nbytes;
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uintptr t, d, b, entry, bssend, text, data, bss, tstk, align;
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uintptr t, d, b, entry, text, data, bss, bssend, tstk, align;
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Segment *s, *ts;
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Image *img;
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Tos *tos;
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@ -311,7 +328,7 @@ sysexec(va_list list)
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}
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nexterror();
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}
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align = BY2PG;
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align = BY2PG-1;
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indir = 0;
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file = file0;
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for(;;){
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@ -323,39 +340,47 @@ sysexec(va_list list)
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if(!indir)
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kstrdup(&elem, up->genbuf);
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n = devtab[tc->type]->read(tc, &exec, sizeof(Exec), 0);
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if(n <= 2)
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error(Ebadexec);
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magic = l2be(exec.magic);
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if(n == sizeof(Exec) && (magic == AOUT_MAGIC)){
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entry = l2be(exec.entry);
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text = l2be(exec.text);
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if(magic & HDR_MAGIC)
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text += 8;
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switch(magic){
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case S_MAGIC: /* 2MB segment alignment for amd64 */
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align = 0x200000;
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break;
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case V_MAGIC: /* 16K segment alignment for mips */
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align = 0x4000;
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break;
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case R_MAGIC: /* 64K segment alignment for arm64 */
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align = 0x10000;
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break;
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n = devtab[tc->type]->read(tc, &ehdr, sizeof(ehdr), 0);
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if(n >= sizeof(Exec)) {
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magic = beswal(ehdr.magic);
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if(magic == AOUT_MAGIC) {
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if(magic & HDR_MAGIC) {
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if(n < sizeof(ehdr))
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error(Ebadexec);
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entry = beswav(ehdr.hdr[0]);
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text = UTZERO+sizeof(ehdr);
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} else {
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entry = beswal(ehdr.entry);
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text = UTZERO+sizeof(Exec);
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}
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if(entry < text)
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error(Ebadexec);
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text += beswal(ehdr.text);
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if(text <= entry || text >= (USTKTOP-USTKSIZE))
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error(Ebadexec);
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switch(magic){
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case S_MAGIC: /* 2MB segment alignment for amd64 */
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align = 0x1fffff;
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break;
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case V_MAGIC: /* 16K segment alignment for mips */
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align = 0x3fff;
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break;
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case R_MAGIC: /* 64K segment alignment for arm64 */
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align = 0xffff;
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break;
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}
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break; /* for binary */
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}
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if(text >= (USTKTOP-USTKSIZE)-(UTZERO+sizeof(Exec))
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|| entry < UTZERO+sizeof(Exec)
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|| entry >= UTZERO+sizeof(Exec)+text)
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error(Ebadexec);
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break; /* for binary */
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}
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if(indir++)
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error(Ebadexec);
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/*
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* Process #! /bin/sh args ...
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*/
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memmove(line, &exec, n);
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if(line[0]!='#' || line[1]!='!' || indir++)
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error(Ebadexec);
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memmove(line, &ehdr, n);
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n = shargs(line, n, progarg);
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if(n < 1)
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error(Ebadexec);
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@ -371,10 +396,10 @@ sysexec(va_list list)
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cclose(tc);
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}
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data = l2be(exec.data);
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bss = l2be(exec.bss);
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align--;
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t = (UTZERO+sizeof(Exec)+text+align) & ~align;
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t = (text+align) & ~align;
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text -= UTZERO;
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data = beswal(ehdr.data);
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bss = beswal(ehdr.bss);
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align = BY2PG-1;
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d = (t + data + align) & ~align;
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bssend = t + data + bss;
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@ -518,7 +543,7 @@ sysexec(va_list list)
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up->seg[TSEG] = ts;
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ts->flushme = 1;
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ts->fstart = 0;
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ts->flen = sizeof(Exec)+text;
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ts->flen = text;
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unlock(img);
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/* Data. Shared. */
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