x86/boot: Rework reserve_real_mode() to allow multiple tries
If reserve_real_mode() fails, panicing immediately means we're
doomed. Make it safe to try more than once to allocate the
trampoline:
- Degrade a failure from panic() to pr_info(). (If we make it to
setup_real_mode() without reserving the trampoline, we'll panic
them.)
- Factor out helpers so that platform code can supply a specific
address to try.
- Warn if reserve_real_mode() is called after we're done with the
memblock allocator. If that were to happen, we would behave
unpredictably.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Matt Fleming <mfleming@suse.de>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/876e383038f3e9971aa72fd20a4f5da05f9d193d.1470821230.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index 747b71e..5db706f1 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -1,4 +1,5 @@
#include <linux/io.h>
+#include <linux/slab.h>
#include <linux/memblock.h>
#include <asm/cacheflush.h>
@@ -12,24 +13,36 @@
/* Hold the pgd entry used on booting additional CPUs */
pgd_t trampoline_pgd_entry;
-void __init reserve_real_mode(void)
+void __init set_real_mode_mem(phys_addr_t mem, size_t size)
{
- phys_addr_t mem;
- unsigned char *base;
- size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
+ void *base = __va(mem);
- /* Has to be under 1M so we can execute real-mode AP code. */
- mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
- if (!mem)
- panic("Cannot allocate trampoline\n");
-
- base = __va(mem);
- memblock_reserve(mem, size);
real_mode_header = (struct real_mode_header *) base;
printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
base, (unsigned long long)mem, size);
}
+void __init reserve_real_mode(void)
+{
+ phys_addr_t mem;
+ size_t size = real_mode_size_needed();
+
+ if (!size)
+ return;
+
+ WARN_ON(slab_is_available());
+
+ /* Has to be under 1M so we can execute real-mode AP code. */
+ mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
+ if (!mem) {
+ pr_info("No sub-1M memory is available for the trampoline\n");
+ return;
+ }
+
+ memblock_reserve(mem, size);
+ set_real_mode_mem(mem, size);
+}
+
static void __init setup_real_mode(void)
{
u16 real_mode_seg;