efi: stub: use high allocation for converted command line

Before we can move the command line processing before the allocation
of the kernel, which is required for detecting the 'nokaslr' option
which controls that allocation, move the converted command line higher
up in memory, to prevent it from interfering with the kernel itself.

Since x86 needs the address to fit in 32 bits, use UINT_MAX as the upper
bound there. Otherwise, use ULONG_MAX (i.e., no limit)

Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 0010c78..08b1f2f 100644 (file)
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -25,6 +25,8 @@
 #define EFI32_LOADER_SIGNATURE "EL32"
 #define EFI64_LOADER_SIGNATURE "EL64"
 
+#define MAX_CMDLINE_ADDRESS    UINT_MAX
+
 #ifdef CONFIG_X86_32
 
 

diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index f07d4a6..29ed2f9 100644 (file)
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -649,6 +649,10 @@ static u8 *efi_utf16_to_utf8(u8 *dst, const u16 *src, int n)
        return dst;
 }
 
+#ifndef MAX_CMDLINE_ADDRESS
+#define MAX_CMDLINE_ADDRESS    ULONG_MAX
+#endif
+
 /*
  * Convert the unicode UEFI command line to ASCII to pass to kernel.
  * Size of memory allocated return in *cmd_line_len.
@@ -684,7 +688,8 @@ char *efi_convert_cmdline(efi_system_table_t *sys_table_arg,
 
        options_bytes++;        /* NUL termination */
 
-       status = efi_low_alloc(sys_table_arg, options_bytes, 0, &cmdline_addr);
+       status = efi_high_alloc(sys_table_arg, options_bytes, 0,
+                               &cmdline_addr, MAX_CMDLINE_ADDRESS);
        if (status != EFI_SUCCESS)
                return NULL;