dump: Dump TLS via sys_arch_prctl

As such -- no need for kernel patch.
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

cr-dump.c

@@ -543,7 +543,6 @@ err:
 
 static int dump_task_tls(pid_t pid, struct desc_struct *tls_array, int size)
 {
-	FILE *file = NULL;
 	int ret = -1;
 
 	if (size != GDT_ENTRY_TLS_ENTRIES) {
@@ -551,43 +550,14 @@ static int dump_task_tls(pid_t pid, struct desc_struct *tls_array, int size)
 		goto err;
 	}
 
-	file = fopen_proc("%d/tls", "r", pid);
-	if (!file) {
-		pr_perror("Can't open %d tls", pid);
-		goto err;
-	}
-
-	ret = 0;
-	while (fgets(loc_buf, sizeof(loc_buf), file)) {
-		u32 a, b;
-		if (sscanf(loc_buf, "%x %x", &a, &b) != 2) {
-			pr_err("Can't parse tls entry: %s\n");
-			ret = -1;
-			goto err;
-		}
-		if (ret >= GDT_ENTRY_TLS_ENTRIES) {
-			pr_err("Too many entries in tls\n");
-			ret = -1;
-			goto err;
-		}
-		tls_array[ret].a = a;
-		tls_array[ret].b = b;
-
-		ret++;
-	}
-
-	if (ret != GDT_ENTRY_TLS_ENTRIES) {
-		pr_err("tls returened %i entries instead of %i\n",
-			 ret, GDT_ENTRY_TLS_ENTRIES);
-		ret = -1;
-		goto err;
-	}
+	memzero(tls_array, sizeof(*tls_array) * size);
 
-	ret = 0;
+	/* pure x86-64 has a base address only */
+	ret = sys_arch_prctl(ARCH_GET_FS, &tls_array[0].base_addr);
+	if (ret)
+		pr_err("Failed to obtain TLS entry: %d\n", ret);
 
 err:
-	if (file)
-		fclose(file);
 	return ret;
 }
 

cr-show.c

@@ -98,7 +98,7 @@ static void show_core_regs(struct cr_fdset *cr_fdset)
 
 	for (i = 0; i < GDT_ENTRY_TLS_ENTRIES; i++) {
 		read_ptr_safe(fd_core, &tls, err);
-		pr_info("tls[%2i] = %x %x\n", i, tls.a, tls.b);
+		pr_info("tls[%2i] = %x\n", i, tls.base_addr);
 	}
 
 err:

include/image.h

@@ -140,8 +140,13 @@ struct user_regs_entry {
 } __packed;
 
 struct desc_struct {
-	u32 a;
-	u32 b;
+ union {
+	struct {
+		u32 a;
+		u32 b;
+	} x86_32;
+	u64	base_addr;
+ };
 } __packed;
 
 struct user_fpregs_entry {

include/types.h

@@ -6,6 +6,12 @@
 
 #include "bitops.h"
 
+/* prctl */
+#define ARCH_SET_GS 0x1001
+#define ARCH_SET_FS 0x1002
+#define ARCH_GET_FS 0x1003
+#define ARCH_GET_GS 0x1004
+
 /* some constants for ptrace */
 #define PTRACE_SEIZE		0x4206
 #define PTRACE_INTERRUPT	0x4207