Commit-ID: 115c6628a59044958c205f8468a1b3ba3d539e61
Gitweb: http://git.kernel.org/tip/115c6628a59044958c205f8468a1b3ba3d539e61
Author: Matt Fleming <matt.fleming@xxxxxxxxx>
AuthorDate: Wed, 24 Sep 2014 11:56:10 +0100
Committer: Matt Fleming <matt.fleming@xxxxxxxxx>
CommitDate: Wed, 24 Sep 2014 21:56:46 +0100
x86/efi: Truncate 64-bit values when calling 32-bit OutputString()
If we're executing the 32-bit efi_char16_printk() code path (i.e.
running on top of 32-bit firmware) we know that efi_early->text_output
will be a 32-bit value, even though ->text_output has type u64.
Unfortunately, we currently pass ->text_output directly to
efi_early->call() so for CONFIG_X86_32 the compiler will push a 64-bit
value onto the stack, causing the other parameters to be misaligned.
The way we handle this in the rest of the EFI boot stub is to pass
pointers as arguments to efi_early->call(), which automatically do the
right thing (pointers are 32-bit on CONFIG_X86_32, and we simply ignore
the upper 32-bits of the argument register if running in 64-bit mode
with 32-bit firmware).
This fixes a corruption bug when printing strings from the 32-bit EFI
boot stub.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=84241
Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>
---
arch/x86/boot/compressed/eboot.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index dc30c17..de8eebd 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -268,18 +268,20 @@ void efi_char16_printk(efi_system_table_t *table, efi_char16_t *str)
offset = offsetof(typeof(*out), output_string);
output_string = efi_early->text_output + offset;
+ out = (typeof(out))(unsigned long)efi_early->text_output;
func = (u64 *)output_string;
- efi_early->call(*func, efi_early->text_output, str);
+ efi_early->call(*func, out, str);
} else {
struct efi_simple_text_output_protocol_32 *out;
u32 *func;
offset = offsetof(typeof(*out), output_string);
output_string = efi_early->text_output + offset;
+ out = (typeof(out))(unsigned long)efi_early->text_output;
func = (u32 *)output_string;
- efi_early->call(*func, efi_early->text_output, str);
+ efi_early->call(*func, out, str);
}
}
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|