diff options
author | Joerg Roedel <jroedel@suse.de> | 2020-09-07 16:15:16 +0300 |
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committer | Borislav Petkov <bp@suse.de> | 2020-09-07 20:45:25 +0300 |
commit | 8b0d3b3b41ab6f14f1ce6d4a6b1c5f60b825123f (patch) | |
tree | 44b616e876f8bf3aa0d8b26f1e29a9e0aa0a50ae /arch/x86/boot/compressed/ident_map_64.c | |
parent | 5f2bb01682b7b067783207994c7b8a3dbeb1cd83 (diff) | |
download | linux-8b0d3b3b41ab6f14f1ce6d4a6b1c5f60b825123f.tar.xz |
x86/boot/compressed/64: Add page-fault handler
Install a page-fault handler to add an identity mapping to addresses
not yet mapped. Also do some checking whether the error code is sane.
This makes non SEV-ES machines use the exception handling
infrastructure in the pre-decompressions boot code too, making it less
likely to break in the future.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200907131613.12703-16-joro@8bytes.org
Diffstat (limited to 'arch/x86/boot/compressed/ident_map_64.c')
-rw-r--r-- | arch/x86/boot/compressed/ident_map_64.c | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c index d9932a133ac9..e3d980ae9c2b 100644 --- a/arch/x86/boot/compressed/ident_map_64.c +++ b/arch/x86/boot/compressed/ident_map_64.c @@ -19,10 +19,13 @@ /* No PAGE_TABLE_ISOLATION support needed either: */ #undef CONFIG_PAGE_TABLE_ISOLATION +#include "error.h" #include "misc.h" /* These actually do the work of building the kernel identity maps. */ #include <linux/pgtable.h> +#include <asm/trap_pf.h> +#include <asm/trapnr.h> #include <asm/init.h> /* Use the static base for this part of the boot process */ #undef __PAGE_OFFSET @@ -160,3 +163,39 @@ void finalize_identity_maps(void) { write_cr3(top_level_pgt); } + +static void do_pf_error(const char *msg, unsigned long error_code, + unsigned long address, unsigned long ip) +{ + error_putstr(msg); + + error_putstr("\nError Code: "); + error_puthex(error_code); + error_putstr("\nCR2: 0x"); + error_puthex(address); + error_putstr("\nRIP relative to _head: 0x"); + error_puthex(ip - (unsigned long)_head); + error_putstr("\n"); + + error("Stopping.\n"); +} + +void do_boot_page_fault(struct pt_regs *regs, unsigned long error_code) +{ + unsigned long address = native_read_cr2(); + + /* + * Check for unexpected error codes. Unexpected are: + * - Faults on present pages + * - User faults + * - Reserved bits set + */ + if (error_code & (X86_PF_PROT | X86_PF_USER | X86_PF_RSVD)) + do_pf_error("Unexpected page-fault:", error_code, address, regs->ip); + + /* + * Error code is sane - now identity map the 2M region around + * the faulting address. + */ + add_identity_map(address & PMD_MASK, PMD_SIZE); +} |