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Re: [Xen-devel] [PATCH v5 07/25] xen/arm: don't add duplicate boot modules, introduce domU flag
Hi Stefano,
On 23/10/2018 03:02, Stefano Stabellini wrote:
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@xxxxxxxxxx>
---
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 | 30 +++++++++++++++++++++++++-----
xen/include/asm-arm/setup.h | 12 ++++++++++--
3 files changed, 42 insertions(+), 11 deletions(-)
diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
index cb6f77d..c325b6e 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 = sizeof("/chosen");
char path[8]; /* sizeof "/chosen" */
int parent_node, ret;
+ bool domU;
parent_node = fdt_parent_offset(fdt, node);
ASSERT(parent_node >= 0);
@@ -229,12 +230,14 @@ 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,
@@ -280,7 +283,7 @@ 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,
@@ -351,7 +354,7 @@ 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..72b12f9 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 +214,29 @@ 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;
}
+/*
+ * This function is only used to find dom0 modules, so check for !mod->domU
This comment is misleading. The function is used not only to find Dom0 Modules
but also XSM & co.
How about:
"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 for guest modules."
+ */
struct bootmodule * __init boot_module_find_by_kind(bootmodule_kind kind)
{
struct bootmodules *mods = &bootinfo.modules;
@@ -229,14 +245,14 @@ 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 +265,7 @@ 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 +275,9 @@ void __init add_boot_cmdline(const char *name, const char
*cmdline,
safe_strcpy(cmd->cmdline, cmdline);
}
+/*
+ * This function is only used to find dom0 modules, so check for !mod->domU
+ */
Same here.
struct bootcmdline * __init boot_cmdline_find_by_kind(bootmodule_kind kind)
{
struct bootcmdlines *cmds = &bootinfo.cmdlines;
@@ -267,7 +287,7 @@ 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 +781,7 @@ 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);
Cheers,
--
Julien Grall
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