Patch "efi: Disable interrupts around EFI calls, not in the epilog/prolog calls" has been added to the 3.10-stable tree

PATCH [email protected] 1 participant 1 message Mar 1, 2016

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Stable branch x86 EFI

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2016-03-01 08:15 UTC #0 lore raw

This is a note to let you know that I've just added the patch titled

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

to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
efi-disable-interrupts-around-efi-calls-not-in-the-epilog-prolog-calls.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 23a0d4e8fa6d3a1d7fb819f79bcc0a3739c30ba9 Mon Sep 17 00:00:00 2001

From: Ingo Molnar <[email protected]>
Date: Tue, 3 Mar 2015 07:34:33 +0100
Subject: efi: Disable interrupts around EFI calls, not in the epilog/prolog calls

From: Ingo Molnar <[email protected]>

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 <[email protected]>

Signed-off-by Ingo Molnar <[email protected]>

Signed-off-by Matt Fleming <[email protected]>

[ luis: backported to 3.10: adjusted context ]

Signed-off-by Luis Henriques <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 arch/x86/platform/efi/efi.c    |    7 +++++++
 arch/x86/platform/efi/efi_32.c |   11 +++--------
 arch/x86/platform/efi/efi_64.c |    3 ---
 3 files changed, 10 insertions(+), 11 deletions(-)

arch/x86/platform/efi/efi.c +7 -0

@@ -250,12 +250,19 @@ static efi_status_t __init phys_efi_set_
 	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;
 }

arch/x86/platform/efi/efi_32.c +3 -8

@@ -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);
 }

arch/x86/platform/efi/efi_64.c +0 -3

@@ -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);
 }

Patches currently in stable-queue which might be from [email protected] are

queue-3.10/efi-disable-interrupts-around-efi-calls-not-in-the-epilog-prolog-calls.patch