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a1c510d0ad
Wire up the generic support for managing task stack allocations via vmalloc, and implement the entry code that detects whether we faulted because of a stack overrun (or future stack overrun caused by pushing the pt_regs array) While this adds a fair amount of tricky entry asm code, it should be noted that it only adds a TST + branch to the svc_entry path. The code implementing the non-trivial handling of the overflow stack is emitted out-of-line into the .text section. Since on ARM, we rely on do_translation_fault() to keep PMD level page table entries that cover the vmalloc region up to date, we need to ensure that we don't hit such a stale PMD entry when accessing the stack. So we do a dummy read from the new stack while still running from the old one on the context switch path, and bump the vmalloc_seq counter when PMD level entries in the vmalloc range are modified, so that the MM switch fetches the latest version of the entries. Note that we need to increase the per-mode stack by 1 word, to gain some space to stash a GPR until we know it is safe to touch the stack. However, due to the cacheline alignment of the struct, this does not actually increase the memory footprint of the struct stack array at all. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
182 lines
3.4 KiB
ArmAsm
182 lines
3.4 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/* ld script to make ARM Linux kernel
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* taken from the i386 version by Russell King
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* Written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
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*/
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#ifdef CONFIG_XIP_KERNEL
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#include "vmlinux-xip.lds.S"
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#else
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#include <linux/pgtable.h>
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#include <asm/vmlinux.lds.h>
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#include <asm/cache.h>
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#include <asm/thread_info.h>
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#include <asm/memory.h>
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#include <asm/mpu.h>
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#include <asm/page.h>
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OUTPUT_ARCH(arm)
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ENTRY(stext)
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#ifndef __ARMEB__
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jiffies = jiffies_64;
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#else
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jiffies = jiffies_64 + 4;
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#endif
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SECTIONS
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{
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/*
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* XXX: The linker does not define how output sections are
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* assigned to input sections when there are multiple statements
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* matching the same input section name. There is no documented
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* order of matching.
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*
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* unwind exit sections must be discarded before the rest of the
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* unwind sections get included.
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*/
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/DISCARD/ : {
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ARM_DISCARD
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#ifndef CONFIG_SMP_ON_UP
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*(.alt.smp.init)
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#endif
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#ifndef CONFIG_ARM_UNWIND
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*(.ARM.exidx) *(.ARM.exidx.*)
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*(.ARM.extab) *(.ARM.extab.*)
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#endif
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}
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. = KERNEL_OFFSET + TEXT_OFFSET;
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.head.text : {
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_text = .;
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HEAD_TEXT
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}
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#ifdef CONFIG_STRICT_KERNEL_RWX
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. = ALIGN(1<<SECTION_SHIFT);
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#endif
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#ifdef CONFIG_ARM_MPU
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. = ALIGN(PMSAv8_MINALIGN);
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#endif
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.text : { /* Real text segment */
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_stext = .; /* Text and read-only data */
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ARM_TEXT
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}
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#ifdef CONFIG_DEBUG_ALIGN_RODATA
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. = ALIGN(1<<SECTION_SHIFT);
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#endif
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_etext = .; /* End of text section */
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RO_DATA(PAGE_SIZE)
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. = ALIGN(4);
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__ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
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__start___ex_table = .;
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ARM_MMU_KEEP(*(__ex_table))
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__stop___ex_table = .;
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}
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#ifdef CONFIG_ARM_UNWIND
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ARM_UNWIND_SECTIONS
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#endif
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#ifdef CONFIG_STRICT_KERNEL_RWX
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. = ALIGN(1<<SECTION_SHIFT);
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#else
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. = ALIGN(PAGE_SIZE);
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#endif
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__init_begin = .;
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ARM_VECTORS
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INIT_TEXT_SECTION(8)
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.exit.text : {
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ARM_EXIT_KEEP(EXIT_TEXT)
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}
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.init.proc.info : {
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ARM_CPU_DISCARD(PROC_INFO)
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}
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.init.arch.info : {
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__arch_info_begin = .;
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*(.arch.info.init)
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__arch_info_end = .;
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}
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.init.tagtable : {
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__tagtable_begin = .;
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*(.taglist.init)
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__tagtable_end = .;
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}
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#ifdef CONFIG_SMP_ON_UP
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.init.smpalt : {
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__smpalt_begin = .;
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*(.alt.smp.init)
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__smpalt_end = .;
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}
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#endif
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.init.pv_table : {
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__pv_table_begin = .;
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*(.pv_table)
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__pv_table_end = .;
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}
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INIT_DATA_SECTION(16)
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.exit.data : {
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ARM_EXIT_KEEP(EXIT_DATA)
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}
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#ifdef CONFIG_SMP
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PERCPU_SECTION(L1_CACHE_BYTES)
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#endif
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#ifdef CONFIG_HAVE_TCM
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ARM_TCM
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#endif
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#ifdef CONFIG_STRICT_KERNEL_RWX
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. = ALIGN(1<<SECTION_SHIFT);
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#else
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. = ALIGN(THREAD_ALIGN);
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#endif
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__init_end = .;
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_sdata = .;
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RW_DATA(L1_CACHE_BYTES, PAGE_SIZE, THREAD_ALIGN)
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_edata = .;
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BSS_SECTION(0, 0, 0)
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#ifdef CONFIG_ARM_MPU
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. = ALIGN(PMSAv8_MINALIGN);
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#endif
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_end = .;
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STABS_DEBUG
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DWARF_DEBUG
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ARM_DETAILS
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ARM_ASSERTS
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}
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#ifdef CONFIG_STRICT_KERNEL_RWX
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/*
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* Without CONFIG_DEBUG_ALIGN_RODATA, __start_rodata_section_aligned will
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* be the first section-aligned location after __start_rodata. Otherwise,
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* it will be equal to __start_rodata.
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*/
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__start_rodata_section_aligned = ALIGN(__start_rodata, 1 << SECTION_SHIFT);
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#endif
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/*
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* These must never be empty
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* If you have to comment these two assert statements out, your
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* binutils is too old (for other reasons as well)
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*/
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ASSERT((__proc_info_end - __proc_info_begin), "missing CPU support")
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#ifndef CONFIG_COMPILE_TEST
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ASSERT((__arch_info_end - __arch_info_begin), "no machine record defined")
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#endif
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#endif /* CONFIG_XIP_KERNEL */
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