From: Arvind Sankar <nivedita@xxxxxxxxxxxx>
[ Upstream commit 81a34892c2c7c809f9c4e22c5ac936ae673fb9a2 ]
The load address is compared with LOAD_PHYSICAL_ADDR using a signed
comparison currently (using jge instruction).
When loading a 64-bit kernel using the new efi32_pe_entry() point added by:
97aa276579b2 ("efi/x86: Add true mixed mode entry point into .compat section")
using Qemu with -m 3072, the firmware actually loads us above 2Gb,
resulting in a very early crash.
Use the JAE instruction to perform a unsigned comparison instead, as physical
addresses should be considered unsigned.
Signed-off-by: Arvind Sankar <nivedita@xxxxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20200301230436.2246909-6-nivedita@xxxxxxxxxxxx
Link: https://lore.kernel.org/r/20200308080859.21568-14-ardb@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/x86/boot/compressed/head_32.S | 2 +-
arch/x86/boot/compressed/head_64.S | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index 37380c0d59996..01d628ea34024 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -106,7 +106,7 @@ ENTRY(startup_32)
notl %eax
andl %eax, %ebx
cmpl $LOAD_PHYSICAL_ADDR, %ebx
- jge 1f
+ jae 1f
#endif
movl $LOAD_PHYSICAL_ADDR, %ebx
1:
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 39fdede523f21..a25127916e679 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -105,7 +105,7 @@ ENTRY(startup_32)
notl %eax
andl %eax, %ebx
cmpl $LOAD_PHYSICAL_ADDR, %ebx
- jge 1f
+ jae 1f
#endif
movl $LOAD_PHYSICAL_ADDR, %ebx
1:
@@ -280,7 +280,7 @@ ENTRY(startup_64)
notq %rax
andq %rax, %rbp
cmpq $LOAD_PHYSICAL_ADDR, %rbp
- jge 1f
+ jae 1f
#endif
movq $LOAD_PHYSICAL_ADDR, %rbp
1:
--
2.20.1
