diff options
Diffstat (limited to 'arch/x86_64/ia32/syscall32.c')
| -rw-r--r-- | arch/x86_64/ia32/syscall32.c | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/arch/x86_64/ia32/syscall32.c b/arch/x86_64/ia32/syscall32.c new file mode 100644 index 000000000000..399ff4985099 --- /dev/null +++ b/arch/x86_64/ia32/syscall32.c @@ -0,0 +1,111 @@ +/* Copyright 2002,2003 Andi Kleen, SuSE Labs */ + +/* vsyscall handling for 32bit processes. Map a stub page into it + on demand because 32bit cannot reach the kernel's fixmaps */ + +#include <linux/mm.h> +#include <linux/string.h> +#include <linux/kernel.h> +#include <linux/gfp.h> +#include <linux/init.h> +#include <linux/stringify.h> +#include <asm/proto.h> +#include <asm/tlbflush.h> +#include <asm/ia32_unistd.h> + +/* 32bit VDSOs mapped into user space. */ +asm(".section \".init.data\",\"aw\"\n" + "syscall32_syscall:\n" + ".incbin \"arch/x86_64/ia32/vsyscall-syscall.so\"\n" + "syscall32_syscall_end:\n" + "syscall32_sysenter:\n" + ".incbin \"arch/x86_64/ia32/vsyscall-sysenter.so\"\n" + "syscall32_sysenter_end:\n" + ".previous"); + +extern unsigned char syscall32_syscall[], syscall32_syscall_end[]; +extern unsigned char syscall32_sysenter[], syscall32_sysenter_end[]; +extern int sysctl_vsyscall32; + +char *syscall32_page; +static int use_sysenter = -1; + +/* + * Map the 32bit vsyscall page on demand. + * + * RED-PEN: This knows too much about high level VM. + * + * Alternative would be to generate a vma with appropriate backing options + * and let it be handled by generic VM. + */ +int __map_syscall32(struct mm_struct *mm, unsigned long address) +{ + pgd_t *pgd; + pud_t *pud; + pte_t *pte; + pmd_t *pmd; + int err = -ENOMEM; + + spin_lock(&mm->page_table_lock); + pgd = pgd_offset(mm, address); + pud = pud_alloc(mm, pgd, address); + if (pud) { + pmd = pmd_alloc(mm, pud, address); + if (pmd && (pte = pte_alloc_map(mm, pmd, address)) != NULL) { + if (pte_none(*pte)) { + set_pte(pte, + mk_pte(virt_to_page(syscall32_page), + PAGE_KERNEL_VSYSCALL32)); + } + /* Flush only the local CPU. Other CPUs taking a fault + will just end up here again + This probably not needed and just paranoia. */ + __flush_tlb_one(address); + err = 0; + } + } + spin_unlock(&mm->page_table_lock); + return err; +} + +int map_syscall32(struct mm_struct *mm, unsigned long address) +{ + int err; + down_read(&mm->mmap_sem); + err = __map_syscall32(mm, address); + up_read(&mm->mmap_sem); + return err; +} + +static int __init init_syscall32(void) +{ + syscall32_page = (void *)get_zeroed_page(GFP_KERNEL); + if (!syscall32_page) + panic("Cannot allocate syscall32 page"); + SetPageReserved(virt_to_page(syscall32_page)); + if (use_sysenter > 0) { + memcpy(syscall32_page, syscall32_sysenter, + syscall32_sysenter_end - syscall32_sysenter); + } else { + memcpy(syscall32_page, syscall32_syscall, + syscall32_syscall_end - syscall32_syscall); + } + return 0; +} + +__initcall(init_syscall32); + +/* May not be __init: called during resume */ +void syscall32_cpu_init(void) +{ + if (use_sysenter < 0) + use_sysenter = (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL); + + /* Load these always in case some future AMD CPU supports + SYSENTER from compat mode too. */ + checking_wrmsrl(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS); + checking_wrmsrl(MSR_IA32_SYSENTER_ESP, 0ULL); + checking_wrmsrl(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target); + + wrmsrl(MSR_CSTAR, ia32_cstar_target); +} |