linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [PATCH] efi: permit calling efi_mem_reserve_persistent from atomic context
@ 2018-11-08 18:05 Ard Biesheuvel
  2018-11-08 20:48 ` Qian Cai
  2018-11-10  2:45 ` Qian Cai
  0 siblings, 2 replies; 6+ messages in thread
From: Ard Biesheuvel @ 2018-11-08 18:05 UTC (permalink / raw)
  To: linux-efi
  Cc: linux-arm-kernel, cai, linux-mm, linux-kernel, marc.zyngier,
	will.deacon, Ard Biesheuvel

Currently, efi_mem_reserve_persistent() may not be called from atomic
context, since both the kmalloc() call and the memremap() call may
sleep.

The kmalloc() call is easy enough to fix, but the memremap() call
needs to be moved into an init hook since we cannot control the
memory allocation behavior of memremap() at the call site.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 drivers/firmware/efi/efi.c | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 249eb70691b0..cfc876e0b67b 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -963,36 +963,43 @@ bool efi_is_table_address(unsigned long phys_addr)
 }
 
 static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock);
+static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init;
 
 int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 {
-	struct linux_efi_memreserve *rsv, *parent;
+	struct linux_efi_memreserve *rsv;
 
-	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
+	if (!efi_memreserve_root)
 		return -ENODEV;
 
-	rsv = kmalloc(sizeof(*rsv), GFP_KERNEL);
+	rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
 	if (!rsv)
 		return -ENOMEM;
 
-	parent = memremap(efi.mem_reserve, sizeof(*rsv), MEMREMAP_WB);
-	if (!parent) {
-		kfree(rsv);
-		return -ENOMEM;
-	}
-
 	rsv->base = addr;
 	rsv->size = size;
 
 	spin_lock(&efi_mem_reserve_persistent_lock);
-	rsv->next = parent->next;
-	parent->next = __pa(rsv);
+	rsv->next = efi_memreserve_root->next;
+	efi_memreserve_root->next = __pa(rsv);
 	spin_unlock(&efi_mem_reserve_persistent_lock);
 
-	memunmap(parent);
+	return 0;
+}
 
+static int __init efi_memreserve_root_init(void)
+{
+	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
+		return -ENODEV;
+
+	efi_memreserve_root = memremap(efi.mem_reserve,
+				       sizeof(*efi_memreserve_root),
+				       MEMREMAP_WB);
+	if (!efi_memreserve_root)
+		return -ENOMEM;
 	return 0;
 }
+early_initcall(efi_memreserve_root_init);
 
 #ifdef CONFIG_KEXEC
 static int update_efi_random_seed(struct notifier_block *nb,
-- 
2.19.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2018-11-12 12:14 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-11-08 18:05 [PATCH] efi: permit calling efi_mem_reserve_persistent from atomic context Ard Biesheuvel
2018-11-08 20:48 ` Qian Cai
2018-11-10  2:45 ` Qian Cai
2018-11-12  2:45   ` Qian Cai
2018-11-12  8:32     ` Marc Zyngier
2018-11-12 12:14       ` Qian Cai

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).