Commit-ID: 5ff3e2c3c3eebe13967d81ad1f23b9468fefea81 Gitweb: http://git.kernel.org/tip/5ff3e2c3c3eebe13967d81ad1f23b9468fefea81 Author: Andy Lutomirski <l...@kernel.org> AuthorDate: Wed, 10 Aug 2016 02:29:16 -0700 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Thu, 11 Aug 2016 11:15:01 +0200
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 <l...@kernel.org> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Josh Poimboeuf <jpoim...@redhat.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Mario Limonciello <mario_limoncie...@dell.com> Cc: Matt Fleming <mflem...@suse.de> Cc: Matthew Garrett <mj...@srcf.ucam.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/876e383038f3e9971aa72fd20a4f5da05f9d193d.1470821230.git.l...@kernel.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/include/asm/realmode.h | 9 +++++++++ arch/x86/realmode/init.c | 29 +++++++++++++++++++++-------- 2 files changed, 30 insertions(+), 8 deletions(-) diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h index 8d67777..b2988c0 100644 --- a/arch/x86/include/asm/realmode.h +++ b/arch/x86/include/asm/realmode.h @@ -58,6 +58,15 @@ extern unsigned char boot_gdt[]; extern unsigned char secondary_startup_64[]; #endif +static inline size_t real_mode_size_needed(void) +{ + if (real_mode_header) + return 0; /* already allocated. */ + + return ALIGN(real_mode_blob_end - real_mode_blob, PAGE_SIZE); +} + +void set_real_mode_mem(phys_addr_t mem, size_t size); void reserve_real_mode(void); #endif /* _ARCH_X86_REALMODE_H */ 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> @@ -12,22 +13,34 @@ u32 *trampoline_cr4_features; /* Hold the pgd entry used on booting additional CPUs */ pgd_t trampoline_pgd_entry; +void __init set_real_mode_mem(phys_addr_t mem, size_t size) +{ + void *base = __va(mem); + + 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; - unsigned char *base; - size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob); + 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) - panic("Cannot allocate trampoline\n"); + if (!mem) { + pr_info("No sub-1M memory is available for the trampoline\n"); + return; + } - 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); + set_real_mode_mem(mem, size); } static void __init setup_real_mode(void)
