Eric Lee / smarc-fsl-linux-kernel

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Commit 5ff3e2c3c3eebe13967d81ad1f23b9468fefea81

Authored by Andy Lutomirski
Committed by Ingo Molnar
1 parent d0de0f685d

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>

Showing 2 changed files with 30 additions and 8 deletions Side-by-side Diff

arch/x86/include/asm/realmode.h
Diff comments   View file @ 5ff3e2c
... ... @@ -58,6 +58,15 @@
58 58 extern unsigned char secondary_startup_64[];
59 59 #endif
60 60  
  61 +static inline size_t real_mode_size_needed(void)
  62 +{
  63 + if (real_mode_header)
  64 + return 0; /* already allocated. */
  65 +
  66 + return ALIGN(real_mode_blob_end - real_mode_blob, PAGE_SIZE);
  67 +}
  68 +
  69 +void set_real_mode_mem(phys_addr_t mem, size_t size);
61 70 void reserve_real_mode(void);
62 71  
63 72 #endif /* _ARCH_X86_REALMODE_H */
arch/x86/realmode/init.c
Diff comments   View file @ 5ff3e2c
1 1 #include <linux/io.h>
  2 +#include <linux/slab.h>
2 3 #include <linux/memblock.h>
3 4  
4 5 #include <asm/cacheflush.h>
5 6  
6 7  
7 8  
8 9  
9 10  
... ... @@ -12,22 +13,34 @@
12 13 /* Hold the pgd entry used on booting additional CPUs */
13 14 pgd_t trampoline_pgd_entry;
14 15  
  16 +void __init set_real_mode_mem(phys_addr_t mem, size_t size)
  17 +{
  18 + void *base = __va(mem);
  19 +
  20 + real_mode_header = (struct real_mode_header *) base;
  21 + printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
  22 + base, (unsigned long long)mem, size);
  23 +}
  24 +
15 25 void __init reserve_real_mode(void)
16 26 {
17 27 phys_addr_t mem;
18   - unsigned char *base;
19   - size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
  28 + size_t size = real_mode_size_needed();
20 29  
  30 + if (!size)
  31 + return;
  32 +
  33 + WARN_ON(slab_is_available());
  34 +
21 35 /* Has to be under 1M so we can execute real-mode AP code. */
22 36 mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
23   - if (!mem)
24   - panic("Cannot allocate trampoline\n");
  37 + if (!mem) {
  38 + pr_info("No sub-1M memory is available for the trampoline\n");
  39 + return;
  40 + }
25 41  
26   - base = __va(mem);
27 42 memblock_reserve(mem, size);
28   - real_mode_header = (struct real_mode_header *) base;
29   - printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
30   - base, (unsigned long long)mem, size);
  43 + set_real_mode_mem(mem, size);
31 44 }
32 45  
33 46 static void __init setup_real_mode(void)