efi: Disable interrupts around EFI calls, not in the epilog/prolog calls

commit 23a0d4e8fa6d3a1d7fb819f79bcc0a3739c30ba9 upstream.

Tapasweni Pathak reported that we do a kmalloc() in efi_call_phys_prolog()
on x86-64 while having interrupts disabled, which is a big no-no, as
kmalloc() can sleep.

Solve this by removing the irq disabling from the prolog/epilog calls
around EFI calls: it's unnecessary, as in this stage we are single
threaded in the boot thread, and we don't ever execute this from
interrupt contexts.

Reported-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
[ luis: backported to 3.10: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 6033be9ff81a1828eaa5c984d304057f75dd0806..3c8bffdc71c8c17e45224dae6453548e4fc80790 100644 (file)
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -250,12 +250,19 @@ static efi_status_t __init phys_efi_set_virtual_address_map(
        efi_memory_desc_t *virtual_map)
 {
        efi_status_t status;
+       unsigned long flags;
 
        efi_call_phys_prelog();
+
+       /* Disable interrupts around EFI calls: */
+       local_irq_save(flags);
        status = efi_call_phys4(efi_phys.set_virtual_address_map,
                                memory_map_size, descriptor_size,
                                descriptor_version, virtual_map);
+       local_irq_restore(flags);
+
        efi_call_phys_epilog();
+
        return status;
 }
 

diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c
index 40e446941dd7eceb587b2b4572c96279631e5f56..bebbee05e331e277008d64fce4cb9ab202cf361e 100644 (file)
--- a/arch/x86/platform/efi/efi_32.c
+++ b/arch/x86/platform/efi/efi_32.c
@@ -33,19 +33,16 @@
 
 /*
  * To make EFI call EFI runtime service in physical addressing mode we need
- * prelog/epilog before/after the invocation to disable interrupt, to
- * claim EFI runtime service handler exclusively and to duplicate a memory in
- * low memory space say 0 - 3G.
+ * prolog/epilog before/after the invocation to claim the EFI runtime service
+ * handler exclusively and to duplicate a memory mapping in low memory space,
+ * say 0 - 3G.
  */
 
-static unsigned long efi_rt_eflags;
 
 void efi_call_phys_prelog(void)
 {
        struct desc_ptr gdt_descr;
 
-       local_irq_save(efi_rt_eflags);
-
        load_cr3(initial_page_table);
        __flush_tlb_all();
 
@@ -64,6 +61,4 @@ void efi_call_phys_epilog(void)
 
        load_cr3(swapper_pg_dir);
        __flush_tlb_all();
-
-       local_irq_restore(efi_rt_eflags);
 }

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 39a0e7f1f0a3ec1c7601888d30c724a5b8660e19..2f6c1a9734c8faaf6ef143fef8f473b09efa8d25 100644 (file)
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -40,7 +40,6 @@
 #include <asm/fixmap.h>
 
 static pgd_t *save_pgd __initdata;
-static unsigned long efi_flags __initdata;
 
 static void __init early_code_mapping_set_exec(int executable)
 {
@@ -66,7 +65,6 @@ void __init efi_call_phys_prelog(void)
        int n_pgds;
 
        early_code_mapping_set_exec(1);
-       local_irq_save(efi_flags);
 
        n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT), PGDIR_SIZE);
        save_pgd = kmalloc(n_pgds * sizeof(pgd_t), GFP_KERNEL);
@@ -90,7 +88,6 @@ void __init efi_call_phys_epilog(void)
                set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), save_pgd[pgd]);
        kfree(save_pgd);
        __flush_tlb_all();
-       local_irq_restore(efi_flags);
        early_code_mapping_set_exec(0);
 }