libmach

1 files changed, 450 insertions, 0 deletions

diff --git a/src/libmach/Linux.c b/src/libmach/Linux.c
new file mode 100644
index 00000000..62796adb
--- /dev/null
+++ b/src/libmach/Linux.c
@@ -0,0 +1,450 @@
+/*
+ * process interface for Linux.
+ * 
+ * Uses ptrace for registers and data,
+ * /proc for some process status.
+ * There's not much point to worrying about
+ * byte order here -- using ptrace means
+ * we're running on the architecture we're debugging,
+ * unless truly weird stuff is going on.
+ *
+ * It is tempting to use /proc/%d/mem along with
+ * the sp and pc in the stat file to get a stack trace
+ * without attaching to the program, but unfortunately
+ * you can't read the mem file unless you've attached.
+ */
+
+#include <u.h>
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include <errno.h>
+#include <libc.h>
+#include <mach.h>
+#include "ureg386.h"
+
+Mach *machcpu = &mach386;
+
+typedef struct PtraceRegs PtraceRegs;
+
+struct PtraceRegs
+{
+	Regs r;
+	int pid;
+};
+
+static int ptracerw(Map*, Seg*, ulong, void*, uint, int);
+static int ptraceregrw(Regs*, char*, ulong*, int);
+
+void
+unmapproc(Map *map)
+{
+	int i;
+
+	if(map == nil)
+		return;
+	for(i=0; i<map->nseg; i++)
+		while(i<map->nseg && map->seg[i].pid){
+			map->nseg--;
+			memmove(&map->seg[i], &map->seg[i+1], 
+				(map->nseg-i)*sizeof(map->seg[0]));
+		}
+}
+
+int
+mapproc(int pid, Map *map, Regs **rp)
+{
+	Seg s;
+	PtraceRegs *r;
+
+	if(ptrace(PTRACE_ATTACH, pid, 0, 0) < 0)
+	if(ptrace(PTRACE_PEEKUSER, pid, 0, 0) < 0)
+	if(ptrace(PTRACE_ATTACH, pid, 0, 0) < 0){
+		werrstr("ptrace attach %d: %r", pid);
+		return -1;
+	}
+
+	if(ctlproc(pid, "waitstop") < 0){
+		ptrace(PTRACE_DETACH, pid, 0, 0);
+		return -1;
+	}
+
+	memset(&s, 0, sizeof s);
+	s.base = 0;
+	s.size = 0xFFFFFFFF;
+	s.offset = 0;
+	s.name = "data";
+	s.file = nil;
+	s.rw = ptracerw;
+	s.pid = pid;
+	if(addseg(map, s) < 0)
+		return -1;
+
+	if((r = mallocz(sizeof(PtraceRegs), 1)) == nil)
+		return -1;
+	r->r.rw = ptraceregrw;
+	r->pid = pid;
+	*rp = (Regs*)r;
+	return 0;
+}
+
+int
+detachproc(int pid)
+{
+	return ptrace(PTRACE_DETACH, pid, 0, 0);
+}
+
+static int
+ptracerw(Map *map, Seg *seg, ulong addr, void *v, uint n, int isr)
+{
+	int i;
+	u32int u;
+	uchar buf[4];
+
+	addr += seg->base;
+	for(i=0; i<n; i+=4){
+		if(isr){
+			errno = 0;
+			u = ptrace(PTRACE_PEEKDATA, seg->pid, addr+i, 0);
+			if(errno)
+				goto ptraceerr;
+			if(n-i >= 4)
+				*(u32int*)((char*)v+i) = u;
+			else{
+				*(u32int*)buf = u;
+				memmove((char*)v+i, buf, n-i);
+			}
+		}else{
+			if(n-i >= 4)
+				u = *(u32int*)((char*)v+i);
+			else{
+				errno = 0;
+				u = ptrace(PTRACE_PEEKDATA, seg->pid, addr+i, 0);
+				if(errno)
+					return -1;
+				*(u32int*)buf = u;
+				memmove(buf, (char*)v+i, n-i);
+				u = *(u32int*)buf;
+			}
+			if(ptrace(PTRACE_POKEDATA, seg->pid, addr+i, &u) < 0)
+				goto ptraceerr;
+		}
+	}
+	return 0;
+
+ptraceerr:
+	werrstr("ptrace: %r");
+	return -1;
+}
+
+static char* linuxregs[] = {
+	"BX",
+	"CX",
+	"DX",
+	"SI",
+	"DI",
+	"BP",
+	"AX",
+	"DS",
+	"ES",
+	"FS",
+	"GS",
+	"OAX",
+	"PC",
+	"CS",
+	"EFLAGS",
+	"SP",
+	"SS",
+};
+
+static ulong
+reg2linux(char *reg)
+{
+	int i;
+
+	for(i=0; i<nelem(linuxregs); i++)
+		if(strcmp(linuxregs[i], reg) == 0)
+			return 4*i;
+	return ~(ulong)0;
+}
+
+static int
+ptraceregrw(Regs *regs, char *name, ulong *val, int isr)
+{
+	int pid;
+	ulong addr;
+	u32int u;
+
+	pid = ((PtraceRegs*)regs)->pid;
+	addr = reg2linux(name);
+	if(~addr == 0){
+		if(isr){
+			*val = ~(ulong)0;
+			return 0;
+		}
+		werrstr("register not available");
+		return -1;
+	}
+	if(isr){
+		errno = 0;
+		u = ptrace(PTRACE_PEEKUSER, pid, addr, 0);
+		if(errno)
+			goto ptraceerr;
+		*val = u;
+	}else{
+		u = *val;
+		if(ptrace(PTRACE_POKEUSER, pid, addr, &u) < 0)
+			goto ptraceerr;
+	}
+	return 0;
+
+ptraceerr:
+	werrstr("ptrace: %r");
+	return -1;
+}
+
+static int
+isstopped(int pid)
+{
+	char buf[1024];
+	int fd, n;
+	char *p;
+
+	snprint(buf, sizeof buf, "/proc/%d/stat", pid);
+	if((fd = open(buf, OREAD)) < 0)
+		return 0;
+	n = read(fd, buf, sizeof buf-1);
+	close(fd);
+	if(n <= 0)
+		return 0;
+	buf[n] = 0;
+
+	/* command name is in parens, no parens afterward */
+	p = strrchr(buf, ')');
+	if(p == nil || *++p != ' ')
+		return 0;
+	++p;
+
+	/* next is state - T is stopped for tracing */
+	return *p == 'T';
+}
+
+/* /proc/pid/stat contains 
+	pid
+	command in parens
+	0. state
+	1. ppid
+	2. pgrp
+	3. session
+	4. tty_nr
+	5. tpgid
+	6. flags (math=4, traced=10)
+	7. minflt
+	8. cminflt
+	9. majflt
+	10. cmajflt
+	11. utime
+	12. stime
+	13. cutime
+	14. cstime
+	15. priority
+	16. nice
+	17. 0
+	18. itrealvalue
+	19. starttime
+	20. vsize
+	21. rss
+	22. rlim
+	23. startcode
+	24. endcode
+	25. startstack
+	26. kstkesp
+	27. kstkeip
+	28. pending signal bitmap
+	29. blocked signal bitmap
+	30. ignored signal bitmap
+	31. caught signal bitmap
+	32. wchan
+	33. nswap
+	34. cnswap
+	35. exit_signal
+	36. processor
+*/
+
+
+int
+procnotes(int pid, char ***pnotes)
+{
+	char buf[1024], *f[40];
+	int fd, i, n, nf;
+	char *p, *s, **notes;
+	ulong sigs;
+	extern char *_p9sigstr(int, char*);
+
+	*pnotes = nil;
+	snprint(buf, sizeof buf, "/proc/%d/stat", pid);
+	if((fd = open(buf, OREAD)) < 0){
+		fprint(2, "open %s: %r\n", buf);
+		return -1;
+	}
+	n = read(fd, buf, sizeof buf-1);
+	close(fd);
+	if(n <= 0){
+		fprint(2, "read %s: %r\n", buf);
+		return -1;
+	}
+	buf[n] = 0;
+
+	/* command name is in parens, no parens afterward */
+	p = strrchr(buf, ')');
+	if(p == nil || *++p != ' '){
+		fprint(2, "bad format in /proc/%d/stat\n", pid);
+		return -1;
+	}
+	++p;
+
+	nf = tokenize(p, f, nelem(f));
+	if(0) print("code 0x%lux-0x%lux stack 0x%lux kstk 0x%lux keip 0x%lux pending 0x%lux\n",
+		strtoul(f[23], 0, 0), strtoul(f[24], 0, 0), strtoul(f[25], 0, 0),
+		strtoul(f[26], 0, 0), strtoul(f[27], 0, 0), strtoul(f[28], 0, 0));
+	if(nf <= 28)
+		return -1;
+
+	sigs = strtoul(f[28], 0, 0) & ~(1<<SIGCONT);
+	if(sigs == 0){
+		*pnotes = nil;
+		return 0;
+	}
+
+	notes = mallocz(32*sizeof(char*), 0);
+	if(notes == nil)
+		return -1;
+	n = 0;
+	for(i=0; i<32; i++){
+		if((sigs&(1<<i)) == 0)
+			continue;
+		if((s = _p9sigstr(i, nil)) == nil)
+			continue;
+		notes[n++] = s;
+	}
+	*pnotes = notes;
+	return n;
+}
+
+#undef waitpid
+
+int
+ctlproc(int pid, char *msg)
+{
+	int p, status;
+
+	if(strcmp(msg, "hang") == 0){
+		if(pid == getpid())
+			return ptrace(PTRACE_TRACEME, 0, 0, 0);
+		werrstr("can only hang self");
+		return -1;
+	}
+	if(strcmp(msg, "kill") == 0)
+		return ptrace(PTRACE_KILL, pid, 0, 0);
+	if(strcmp(msg, "startstop") == 0){
+		if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
+			return -1;
+		goto waitstop;
+	}
+	if(strcmp(msg, "sysstop") == 0){
+		if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
+			return -1;
+		goto waitstop;
+	}
+	if(strcmp(msg, "stop") == 0){
+		if(kill(pid, SIGSTOP) < 0)
+			return -1;
+		goto waitstop;
+	}
+	if(strcmp(msg, "waitstop") == 0){
+	waitstop:
+		if(isstopped(pid))
+			return 0;
+		for(;;){
+			p = waitpid(pid, &status, WUNTRACED);
+			if(p <= 0)
+				return -1;
+			if(WIFEXITED(status) || WIFSTOPPED(status))
+				return 0;
+		}
+	}
+	if(strcmp(msg, "start") == 0)
+		return ptrace(PTRACE_CONT, pid, 0, 0);
+	werrstr("unknown control message '%s'", msg);
+	return -1;
+}
+
+char*
+proctextfile(int pid)
+{
+	static char buf[1024], pbuf[128];
+
+	snprint(pbuf, sizeof pbuf, "/proc/%d/exe", pid);
+	if(readlink(pbuf, buf, sizeof buf) >= 0)
+		return buf;
+	if(access(pbuf, AEXIST) >= 0)
+		return pbuf;
+	return nil;
+}
+
+
+#if 0
+	snprint(buf, sizeof buf, "/proc/%d/maps", pid);
+	if((b = Bopen(buf, OREAD)) == nil){
+		werrstr("open %s: %r", buf);
+		return -1;
+	}
+
+/*
+        08048000-08056000 r-xp 00000000 03:0c 64593      /usr/sbin/gpm
+        08056000-08058000 rw-p 0000d000 03:0c 64593      /usr/sbin/gpm
+        08058000-0805b000 rwxp 00000000 00:00 0
+        40000000-40013000 r-xp 00000000 03:0c 4165       /lib/ld-2.2.4.so
+        40013000-40015000 rw-p 00012000 03:0c 4165       /lib/ld-2.2.4.so
+        4001f000-40135000 r-xp 00000000 03:0c 45494      /lib/libc-2.2.4.so
+        40135000-4013e000 rw-p 00115000 03:0c 45494      /lib/libc-2.2.4.so
+        4013e000-40142000 rw-p 00000000 00:00 0
+        bffff000-c0000000 rwxp 00000000 00:00 0
+*/
+
+	file = nil;
+	while((p = Brdline(b, '\n')) != nil){
+		p[Blinelen(b)-1] = 0;
+		memset(f, 0, sizeof f);
+		if((nf = getfields(p, f, 6, 1, " ")) < 5)
+			continue;
+		base = strtoul(f[0], &p, 16);
+		if(*p != '-')
+			continue;
+		end = strtoul(p+1, &p, 16);
+		if(*p != 0)
+			continue;
+		offset = strtoul(f[2], &p, 16);
+		if(*p != 0)
+			continue;
+		if(nf == 6)
+			file = f[5];
+		zero = atoi(f[4]) == 0;
+		print("%lux-%lux %lux %s %s\n", base, end, offset, zero ? "data" : "text", file ? file : "");
+		s.base = base;
+		s.size = end - base;
+		s.offset = offset;
+		s.name = zero ? "data" : "text";
+		s.file = strdup(file);
+		s.rw = ptracerw;
+		s.pid = pid;
+		if(addseg(map, s) < 0){
+			Bterm(b);
+			ptrace(PTRACE_DETACH, pid, 0, 0);
+			return -1;
+		}
+	}
+	Bterm(b);
+#endif
+