Commit-ID: fb5268354d20b82c12569e325b0d051c09f983f7 Gitweb: https://git.kernel.org/tip/fb5268354d20b82c12569e325b0d051c09f983f7 Author: Kirill A. Shutemov <[email protected]> AuthorDate: Mon, 26 Feb 2018 21:04:49 +0300 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 12 Mar 2018 09:37:25 +0100
x86/boot/compressed/64: Save and restore trampoline memory The memory area we found for trampoline shouldn't contain anything useful. But let's preserve the data anyway. Just to be on safe side. paging_prepare() would save the data into a buffer. cleanup_trampoline() would restore it back once we are done with the trampoline. Tested-by: Borislav Petkov <[email protected]> Signed-off-by: Kirill A. Shutemov <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Andy Shevchenko <[email protected]> Cc: Cyrill Gorcunov <[email protected]> Cc: Eric Biederman <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Juergen Gross <[email protected]> Cc: Kees Cook <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/boot/compressed/head_64.S | 10 ++++++++++ arch/x86/boot/compressed/pgtable_64.c | 13 +++++++++++++ 2 files changed, 23 insertions(+) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index d598d65db32c..8ba0582c65d5 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -355,6 +355,16 @@ ENTRY(startup_64) lretq lvl5: + /* + * cleanup_trampoline() would restore trampoline memory. + * + * RSI holds real mode data and needs to be preserved across + * this function call. + */ + pushq %rsi + call cleanup_trampoline + popq %rsi + /* Zero EFLAGS */ pushq $0 popfq diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c index 21d5cc1cd5fa..01d08d3e3e43 100644 --- a/arch/x86/boot/compressed/pgtable_64.c +++ b/arch/x86/boot/compressed/pgtable_64.c @@ -1,5 +1,6 @@ #include <asm/processor.h> #include "pgtable.h" +#include "../string.h" /* * __force_order is used by special_insns.h asm code to force instruction @@ -18,6 +19,9 @@ struct paging_config { unsigned long l5_required; }; +/* Buffer to preserve trampoline memory */ +static char trampoline_save[TRAMPOLINE_32BIT_SIZE]; + /* * Trampoline address will be printed by extract_kernel() for debugging * purposes. @@ -69,5 +73,14 @@ struct paging_config paging_prepare(void) trampoline_32bit = (unsigned long *)paging_config.trampoline_start; + /* Preserve trampoline memory */ + memcpy(trampoline_save, trampoline_32bit, TRAMPOLINE_32BIT_SIZE); + return paging_config; } + +void cleanup_trampoline(void) +{ + /* Restore trampoline memory */ + memcpy(trampoline_32bit, trampoline_save, TRAMPOLINE_32BIT_SIZE); +}
