[PATCH v6 07/26] xen/arm: don't add duplicate boot modules, introduce domU flag

[Stefano Stabellini <sstabellini@kernel.org>]

Don't add duplicate boot modules (same kind and same start address),
they are freed later, we don't want to introduce double-free errors.

Introduce a domU flag in struct bootmodule and struct bootcmdline. Set
it for kernels and ramdisks of "xen,domain" nodes to avoid getting
confused in kernel_probe, where we try to guess which is the dom0 kernel
and initrd to be compatible with all versions of the multiboot spec.

boot_module_find_by_kind and boot_cmdline_find_by_kind automatically
check for !domU entries (they are only used for non-domU modules).

Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>

---
Changes in v6:
- update comments

Changes in v5:
- improve commit message
- add in-code comments

Changes in v4:
- use unsigned int
- better commit message
- introduce domU flag and usage

Changes in v2:
- new patch
---
 xen/arch/arm/bootfdt.c      | 11 +++++++----
 xen/arch/arm/setup.c        | 34 +++++++++++++++++++++++++++++-----
 xen/include/asm-arm/setup.h | 12 ++++++++++--
 3 files changed, 46 insertions(+), 11 deletions(-)

diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
index 07a9037..8d9ba47 100644
--- a/xen/arch/arm/bootfdt.c
+++ b/xen/arch/arm/bootfdt.c
@@ -175,6 +175,7 @@ static void __init process_multiboot_node(const void *fdt, int node,
     int len = 8; /* sizeof "/chosen" */
     char path[8];
     int parent_node, ret;
+    bool domU;
 
     parent_node = fdt_parent_offset(fdt, node);
     ASSERT(parent_node >= 0);
@@ -230,12 +231,14 @@ static void __init process_multiboot_node(const void *fdt, int node,
             kind = BOOTMOD_XSM;
     }
 
-    add_boot_module(kind, start, size);
+    domU = fdt_node_check_compatible(fdt, parent_node, "xen,domain") == 0;
+    add_boot_module(kind, start, size, domU);
 
     prop = fdt_get_property(fdt, node, "bootargs", &len);
     if ( !prop )
         return;
-    add_boot_cmdline(fdt_get_name(fdt, parent_node, &len), prop->data, kind);
+    add_boot_cmdline(fdt_get_name(fdt, parent_node, &len), prop->data,
+                     kind, domU);
 }
 
 static void __init process_chosen_node(const void *fdt, int node,
@@ -281,7 +284,7 @@ static void __init process_chosen_node(const void *fdt, int node,
 
     printk("Initrd %"PRIpaddr"-%"PRIpaddr"\n", start, end);
 
-    add_boot_module(BOOTMOD_RAMDISK, start, end-start);
+    add_boot_module(BOOTMOD_RAMDISK, start, end-start, false);
 }
 
 static int __init early_scan_node(const void *fdt,
@@ -352,7 +355,7 @@ size_t __init boot_fdt_info(const void *fdt, paddr_t paddr)
     if ( ret < 0 )
         panic("No valid device tree\n");
 
-    add_boot_module(BOOTMOD_FDT, paddr, fdt_totalsize(fdt));
+    add_boot_module(BOOTMOD_FDT, paddr, fdt_totalsize(fdt), false);
 
     device_tree_for_each_node((void *)fdt, early_scan_node, NULL);
     early_print_info();
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 2098591..c69e872 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -201,10 +201,12 @@ void __init dt_unreserved_regions(paddr_t s, paddr_t e,
 }
 
 struct bootmodule __init *add_boot_module(bootmodule_kind kind,
-                                          paddr_t start, paddr_t size)
+                                          paddr_t start, paddr_t size,
+                                          bool domU)
 {
     struct bootmodules *mods = &bootinfo.modules;
     struct bootmodule *mod;
+    unsigned int i;
 
     if ( mods->nr_mods == MAX_MODULES )
     {
@@ -212,15 +214,31 @@ struct bootmodule __init *add_boot_module(bootmodule_kind kind,
                boot_module_kind_as_string(kind), start, start + size);
         return NULL;
     }
+    for ( i = 0 ; i < mods->nr_mods ; i++ )
+    {
+        mod = &mods->module[i];
+        if ( mod->kind == kind && mod->start == start )
+        {
+            if ( !domU )
+                mod->domU = false;
+            return mod;
+        }
+    }
 
     mod = &mods->module[mods->nr_mods++];
     mod->kind = kind;
     mod->start = start;
     mod->size = size;
+    mod->domU = domU;
 
     return mod;
 }
 
+/*
+ * boot_module_find_by_kind can only be used to return Xen modules (e.g
+ * XSM, DTB) or Dom0 modules. This is not suitable for looking up guest
+ * modules.
+ */
 struct bootmodule * __init boot_module_find_by_kind(bootmodule_kind kind)
 {
     struct bootmodules *mods = &bootinfo.modules;
@@ -229,14 +247,14 @@ struct bootmodule * __init boot_module_find_by_kind(bootmodule_kind kind)
     for (i = 0 ; i < mods->nr_mods ; i++ )
     {
         mod = &mods->module[i];
-        if ( mod->kind == kind )
+        if ( mod->kind == kind && !mod->domU )
             return mod;
     }
     return NULL;
 }
 
 void __init add_boot_cmdline(const char *name, const char *cmdline,
-                             bootmodule_kind kind)
+                             bootmodule_kind kind, bool domU)
 {
     struct bootcmdlines *cmds = &bootinfo.cmdlines;
     struct bootcmdline *cmd;
@@ -249,6 +267,7 @@ void __init add_boot_cmdline(const char *name, const char *cmdline,
 
     cmd = &cmds->cmdline[cmds->nr_mods++];
     cmd->kind = kind;
+    cmd->domU = domU;
 
     ASSERT(strlen(name) <= DT_MAX_NAME);
     safe_strcpy(cmd->dt_name, name);
@@ -258,6 +277,11 @@ void __init add_boot_cmdline(const char *name, const char *cmdline,
     safe_strcpy(cmd->cmdline, cmdline);
 }
 
+/*
+ * boot_cmdline_find_by_kind can only be used to return Xen modules (e.g
+ * XSM, DTB) or Dom0 modules. This is not suitable for looking up guest
+ * modules.
+ */
 struct bootcmdline * __init boot_cmdline_find_by_kind(bootmodule_kind kind)
 {
     struct bootcmdlines *cmds = &bootinfo.cmdlines;
@@ -267,7 +291,7 @@ struct bootcmdline * __init boot_cmdline_find_by_kind(bootmodule_kind kind)
     for ( i = 0 ; i < cmds->nr_mods ; i++ )
     {
         cmd = &cmds->cmdline[i];
-        if ( cmd->kind == kind )
+        if ( cmd->kind == kind && !cmd->domU )
             return cmd;
     }
     return NULL;
@@ -761,7 +785,7 @@ void __init start_xen(unsigned long boot_phys_offset,
     /* Register Xen's load address as a boot module. */
     xen_bootmodule = add_boot_module(BOOTMOD_XEN,
                              (paddr_t)(uintptr_t)(_start + boot_phys_offset),
-                             (paddr_t)(uintptr_t)(_end - _start + 1));
+                             (paddr_t)(uintptr_t)(_end - _start + 1), false);
     BUG_ON(!xen_bootmodule);
 
     xen_paddr = get_xen_paddr();
diff --git a/xen/include/asm-arm/setup.h b/xen/include/asm-arm/setup.h
index 7580007..3a30329 100644
--- a/xen/include/asm-arm/setup.h
+++ b/xen/include/asm-arm/setup.h
@@ -30,9 +30,16 @@ struct meminfo {
     struct membank bank[NR_MEM_BANKS];
 };
 
+/*
+ * The domU flag is set for kernels and ramdisks of "xen,domain" nodes.
+ * The purpose of the domU flag is to avoid getting confused in
+ * kernel_probe, where we try to guess which is the dom0 kernel and
+ * initrd to be compatible with all versions of the multiboot spec. 
+ */
 #define BOOTMOD_MAX_CMDLINE 1024
 struct bootmodule {
     bootmodule_kind kind;
+    bool domU;
     paddr_t start;
     paddr_t size;
 };
@@ -41,6 +48,7 @@ struct bootmodule {
 #define DT_MAX_NAME 41
 struct bootcmdline {
     bootmodule_kind kind;
+    bool domU;
     char dt_name[DT_MAX_NAME];
     char cmdline[BOOTMOD_MAX_CMDLINE];
 };
@@ -91,10 +99,10 @@ size_t __init boot_fdt_info(const void *fdt, paddr_t paddr);
 const char __init *boot_fdt_cmdline(const void *fdt);
 
 struct bootmodule *add_boot_module(bootmodule_kind kind,
-                                   paddr_t start, paddr_t size);
+                                   paddr_t start, paddr_t size, bool domU);
 struct bootmodule *boot_module_find_by_kind(bootmodule_kind kind);
 void add_boot_cmdline(const char *name, const char *cmdline,
-                      bootmodule_kind kind);
+                      bootmodule_kind kind, bool domU);
 struct bootcmdline *boot_cmdline_find_by_kind(bootmodule_kind kind);
 const char * __init boot_module_kind_as_string(bootmodule_kind kind);
 
-- 
1.9.1


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