Commit-ID: c603a309cc75f3dd018ddb20ee44c05047918cbf Gitweb: https://git.kernel.org/tip/c603a309cc75f3dd018ddb20ee44c05047918cbf Author: Thomas Lendacky <thomas.lenda...@amd.com> AuthorDate: Wed, 19 Jun 2019 18:40:57 +0000 Committer: Borislav Petkov <b...@suse.de> CommitDate: Thu, 20 Jun 2019 09:22:47 +0200
x86/mm: Identify the end of the kernel area to be reserved The memory occupied by the kernel is reserved using memblock_reserve() in setup_arch(). Currently, the area is from symbols _text to __bss_stop. Everything after __bss_stop must be specifically reserved otherwise it is discarded. This is not clearly documented. Add a new symbol, __end_of_kernel_reserve, that more readily identifies what is reserved, along with comments that indicate what is reserved, what is discarded and what needs to be done to prevent a section from being discarded. Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com> Signed-off-by: Borislav Petkov <b...@suse.de> Reviewed-by: Baoquan He <b...@redhat.com> Reviewed-by: Dave Hansen <dave.han...@intel.com> Tested-by: Lianbo Jiang <liji...@redhat.com> Cc: Andy Lutomirski <l...@kernel.org> Cc: Brijesh Singh <brijesh.si...@amd.com> Cc: Dave Young <dyo...@redhat.com> Cc: "H. Peter Anvin" <h...@zytor.com> Cc: Ingo Molnar <mi...@redhat.com> Cc: Joerg Roedel <jroe...@suse.de> Cc: Juergen Gross <jgr...@suse.com> Cc: Kees Cook <keesc...@chromium.org> Cc: Nick Desaulniers <ndesaulni...@google.com> Cc: Pavel Tatashin <pasha.tatas...@oracle.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Robert Richter <rrich...@marvell.com> Cc: Sami Tolvanen <samitolva...@google.com> Cc: Sinan Kaya <ok...@codeaurora.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: "x...@kernel.org" <x...@kernel.org> Link: https://lkml.kernel.org/r/7db7da45b435f8477f25e66f292631ff766a844c.1560969363.git.thomas.lenda...@amd.com --- arch/x86/include/asm/sections.h | 2 ++ arch/x86/kernel/setup.c | 8 +++++++- arch/x86/kernel/vmlinux.lds.S | 9 ++++++++- 3 files changed, 17 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h index 8ea1cfdbeabc..71b32f2570ab 100644 --- a/arch/x86/include/asm/sections.h +++ b/arch/x86/include/asm/sections.h @@ -13,4 +13,6 @@ extern char __end_rodata_aligned[]; extern char __end_rodata_hpage_align[]; #endif +extern char __end_of_kernel_reserve[]; + #endif /* _ASM_X86_SECTIONS_H */ diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 08a5f4a131f5..dac60ad37e5e 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -827,8 +827,14 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p) void __init setup_arch(char **cmdline_p) { + /* + * Reserve the memory occupied by the kernel between _text and + * __end_of_kernel_reserve symbols. Any kernel sections after the + * __end_of_kernel_reserve symbol must be explicitly reserved with a + * separate memblock_reserve() or they will be discarded. + */ memblock_reserve(__pa_symbol(_text), - (unsigned long)__bss_stop - (unsigned long)_text); + (unsigned long)__end_of_kernel_reserve - (unsigned long)_text); /* * Make sure page 0 is always reserved because on systems with diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 0850b5149345..ca2252ca6ad7 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -368,6 +368,14 @@ SECTIONS __bss_stop = .; } + /* + * The memory occupied from _text to here, __end_of_kernel_reserve, is + * automatically reserved in setup_arch(). Anything after here must be + * explicitly reserved using memblock_reserve() or it will be discarded + * and treated as available memory. + */ + __end_of_kernel_reserve = .; + . = ALIGN(PAGE_SIZE); .brk : AT(ADDR(.brk) - LOAD_OFFSET) { __brk_base = .; @@ -382,7 +390,6 @@ SECTIONS STABS_DEBUG DWARF_DEBUG - /* Sections to be discarded */ DISCARDS /DISCARD/ : { *(.eh_frame)
