From 23e60394046a831d3245f83c0f5d46dee7d83326 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 24 Dec 2019 16:10:20 +0100 Subject: efi/libstub/x86: Work around page freeing issue in mixed mode Mixed mode translates calls from the 64-bit kernel into the 32-bit firmware by wrapping them in a call to a thunking routine that pushes a 32-bit word onto the stack for each argument passed to the function, regardless of the argument type. This works surprisingly well for most services and protocols, with the exception of ones that take explicit 64-bit arguments. efi_free() invokes the FreePages() EFI boot service, which takes a efi_physical_addr_t as its address argument, and this is one of those 64-bit types. This means that the 32-bit firmware will interpret the (addr, size) pair as a single 64-bit quantity, and since it is guaranteed to have the high word set (as size > 0), it will always fail due to the fact that EFI memory allocations are always < 4 GB on 32-bit firmware. So let's fix this by giving the thunking code a little hand, and pass two values for the address, and a third one for the size. Signed-off-by: Ard Biesheuvel Cc: Arvind Sankar Cc: Borislav Petkov Cc: James Morse Cc: Matt Fleming Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: https://lkml.kernel.org/r/20191224151025.32482-21-ardb@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/boot/compressed/eboot.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'arch/x86/boot') diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c index f81dd66626ce..ec92c4decc86 100644 --- a/arch/x86/boot/compressed/eboot.c +++ b/arch/x86/boot/compressed/eboot.c @@ -901,3 +901,19 @@ fail: for (;;) asm("hlt"); } + +#ifdef CONFIG_EFI_MIXED +void efi_free_native(unsigned long size, unsigned long addr); + +void efi_free(unsigned long size, unsigned long addr) +{ + if (!size) + return; + + if (efi_is_native()) + efi_free_native(size, addr); + else + efi64_thunk(efi_system_table()->boottime->mixed_mode.free_pages, + addr, 0, DIV_ROUND_UP(size, EFI_PAGE_SIZE)); +} +#endif -- cgit v1.2.3-59-g8ed1b