[PATCH] x86: __pa and __pa_symbol address space separation
Currently __pa_symbol is for use with symbols in the kernel address map and __pa is for use with pointers into the physical memory map. But the code is implemented so you can usually interchange the two. __pa which is much more common can be implemented much more cheaply if it is it doesn't have to worry about any other kernel address spaces. This is especially true with a relocatable kernel as __pa_symbol needs to peform an extra variable read to resolve the address. There is a third macro that is added for the vsyscall data __pa_vsymbol for finding the physical addesses of vsyscall pages. Most of this patch is simply sorting through the references to __pa or __pa_symbol and using the proper one. A little of it is continuing to use a physical address when we have it instead of recalculating it several times. swapper_pgd is now NULL. leave_mm now uses init_mm.pgd and init_mm.pgd is initialized at boot (instead of compile time) to the physmem virtual mapping of init_level4_pgd. The physical address changed. Except for the for EMPTY_ZERO page all of the remaining references to __pa_symbol appear to be during kernel initialization. So this should reduce the cost of __pa in the common case, even on a relocated kernel. As this is technically a semantic change we need to be on the lookout for anything I missed. But it works for me (tm). Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
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1b29c1643c
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@ -402,8 +402,8 @@ void __init alternative_instructions(void)
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_text, _etext);
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}
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free_init_pages("SMP alternatives",
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(unsigned long)__smp_alt_begin,
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(unsigned long)__smp_alt_end);
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__pa_symbol(&__smp_alt_begin),
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__pa_symbol(&__smp_alt_end));
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} else {
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alternatives_smp_save(__smp_alt_instructions,
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__smp_alt_instructions_end);
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@ -774,10 +774,11 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end)
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unsigned long addr;
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for (addr = begin; addr < end; addr += PAGE_SIZE) {
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ClearPageReserved(virt_to_page(addr));
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init_page_count(virt_to_page(addr));
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memset((void *)addr, POISON_FREE_INITMEM, PAGE_SIZE);
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free_page(addr);
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struct page *page = pfn_to_page(addr >> PAGE_SHIFT);
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ClearPageReserved(page);
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init_page_count(page);
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memset(page_address(page), POISON_FREE_INITMEM, PAGE_SIZE);
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__free_page(page);
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totalram_pages++;
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}
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printk(KERN_INFO "Freeing %s: %ldk freed\n", what, (end - begin) >> 10);
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@ -786,14 +787,14 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end)
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void free_initmem(void)
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{
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free_init_pages("unused kernel memory",
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(unsigned long)(&__init_begin),
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(unsigned long)(&__init_end));
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__pa_symbol(&__init_begin),
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__pa_symbol(&__init_end));
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}
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#ifdef CONFIG_BLK_DEV_INITRD
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void free_initrd_mem(unsigned long start, unsigned long end)
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{
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free_init_pages("initrd memory", start, end);
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free_init_pages("initrd memory", __pa(start), __pa(end));
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}
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#endif
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@ -191,19 +191,19 @@ NORET_TYPE void machine_kexec(struct kimage *image)
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page_list[PA_CONTROL_PAGE] = __pa(control_page);
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page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
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page_list[PA_PGD] = __pa(kexec_pgd);
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page_list[PA_PGD] = __pa_symbol(&kexec_pgd);
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page_list[VA_PGD] = (unsigned long)kexec_pgd;
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page_list[PA_PUD_0] = __pa(kexec_pud0);
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page_list[PA_PUD_0] = __pa_symbol(&kexec_pud0);
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page_list[VA_PUD_0] = (unsigned long)kexec_pud0;
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page_list[PA_PMD_0] = __pa(kexec_pmd0);
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page_list[PA_PMD_0] = __pa_symbol(&kexec_pmd0);
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page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;
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page_list[PA_PTE_0] = __pa(kexec_pte0);
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page_list[PA_PTE_0] = __pa_symbol(&kexec_pte0);
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page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
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page_list[PA_PUD_1] = __pa(kexec_pud1);
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page_list[PA_PUD_1] = __pa_symbol(&kexec_pud1);
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page_list[VA_PUD_1] = (unsigned long)kexec_pud1;
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page_list[PA_PMD_1] = __pa(kexec_pmd1);
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page_list[PA_PMD_1] = __pa_symbol(&kexec_pmd1);
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page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;
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page_list[PA_PTE_1] = __pa(kexec_pte1);
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page_list[PA_PTE_1] = __pa_symbol(&kexec_pte1);
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page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
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page_list[PA_TABLE_PAGE] =
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@ -243,11 +243,12 @@ void __init setup_arch(char **cmdline_p)
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init_mm.end_code = (unsigned long) &_etext;
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init_mm.end_data = (unsigned long) &_edata;
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init_mm.brk = (unsigned long) &_end;
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init_mm.pgd = __va(__pa_symbol(&init_level4_pgt));
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code_resource.start = virt_to_phys(&_text);
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code_resource.end = virt_to_phys(&_etext)-1;
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data_resource.start = virt_to_phys(&_etext);
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data_resource.end = virt_to_phys(&_edata)-1;
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code_resource.start = __pa_symbol(&_text);
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code_resource.end = __pa_symbol(&_etext)-1;
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data_resource.start = __pa_symbol(&_etext);
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data_resource.end = __pa_symbol(&_edata)-1;
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early_identify_cpu(&boot_cpu_data);
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@ -76,7 +76,7 @@ static inline void leave_mm(int cpu)
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if (read_pda(mmu_state) == TLBSTATE_OK)
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BUG();
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cpu_clear(cpu, read_pda(active_mm)->cpu_vm_mask);
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load_cr3(swapper_pg_dir);
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load_cr3(init_mm.pgd);
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}
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/*
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@ -45,6 +45,11 @@
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#define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr)))
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#define __syscall_clobber "r11","rcx","memory"
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#define __pa_vsymbol(x) \
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({unsigned long v; \
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extern char __vsyscall_0; \
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asm("" : "=r" (v) : "0" (x)); \
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((v - VSYSCALL_FIRST_PAGE) + __pa_symbol(&__vsyscall_0)); })
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struct vsyscall_gtod_data_t {
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seqlock_t lock;
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@ -224,10 +229,10 @@ static int vsyscall_sysctl_change(ctl_table *ctl, int write, struct file * filp,
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return ret;
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/* gcc has some trouble with __va(__pa()), so just do it this
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way. */
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map1 = ioremap(__pa_symbol(&vsysc1), 2);
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map1 = ioremap(__pa_vsymbol(&vsysc1), 2);
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if (!map1)
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return -ENOMEM;
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map2 = ioremap(__pa_symbol(&vsysc2), 2);
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map2 = ioremap(__pa_vsymbol(&vsysc2), 2);
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if (!map2) {
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ret = -ENOMEM;
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goto out;
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@ -565,11 +565,11 @@ void free_init_pages(char *what, unsigned long begin, unsigned long end)
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printk(KERN_INFO "Freeing %s: %ldk freed\n", what, (end - begin) >> 10);
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for (addr = begin; addr < end; addr += PAGE_SIZE) {
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ClearPageReserved(virt_to_page(addr));
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init_page_count(virt_to_page(addr));
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memset((void *)(addr & ~(PAGE_SIZE-1)),
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POISON_FREE_INITMEM, PAGE_SIZE);
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free_page(addr);
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struct page *page = pfn_to_page(addr >> PAGE_SHIFT);
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ClearPageReserved(page);
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init_page_count(page);
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memset(page_address(page), POISON_FREE_INITMEM, PAGE_SIZE);
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__free_page(page);
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totalram_pages++;
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}
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}
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@ -579,17 +579,18 @@ void free_initmem(void)
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memset(__initdata_begin, POISON_FREE_INITDATA,
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__initdata_end - __initdata_begin);
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free_init_pages("unused kernel memory",
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(unsigned long)(&__init_begin),
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(unsigned long)(&__init_end));
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__pa_symbol(&__init_begin),
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__pa_symbol(&__init_end));
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}
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#ifdef CONFIG_DEBUG_RODATA
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void mark_rodata_ro(void)
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{
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unsigned long addr = (unsigned long)__start_rodata;
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unsigned long addr = (unsigned long)__va(__pa_symbol(&__start_rodata));
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unsigned long end = (unsigned long)__va(__pa_symbol(&__end_rodata));
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for (; addr < (unsigned long)__end_rodata; addr += PAGE_SIZE)
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for (; addr < end; addr += PAGE_SIZE)
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change_page_attr_addr(addr, 1, PAGE_KERNEL_RO);
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printk ("Write protecting the kernel read-only data: %luk\n",
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#ifdef CONFIG_BLK_DEV_INITRD
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void free_initrd_mem(unsigned long start, unsigned long end)
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{
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free_init_pages("initrd memory", start, end);
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free_init_pages("initrd memory", __pa(start), __pa(end));
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}
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#endif
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@ -51,7 +51,6 @@ static struct page *split_large_page(unsigned long address, pgprot_t prot,
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SetPagePrivate(base);
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page_private(base) = 0;
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address = __pa(address);
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addr = address & LARGE_PAGE_MASK;
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pbase = (pte_t *)page_address(base);
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for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
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* No more special protections in this 2/4MB area - revert to a
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* large page again.
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*/
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static void revert_page(unsigned long address, pgprot_t ref_prot)
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static void revert_page(unsigned long address, unsigned long pfn, pgprot_t ref_prot)
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{
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pgd_t *pgd;
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pud_t *pud;
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pmd_t *pmd;
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pte_t large_pte;
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unsigned long pfn;
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pgd = pgd_offset_k(address);
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BUG_ON(pgd_none(*pgd));
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BUG_ON(pud_none(*pud));
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pmd = pmd_offset(pud, address);
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BUG_ON(pmd_val(*pmd) & _PAGE_PSE);
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pfn = (__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT;
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large_pte = pfn_pte(pfn, ref_prot);
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large_pte = pte_mkhuge(large_pte);
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set_pte((pte_t *)pmd, large_pte);
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*/
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struct page *split;
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ref_prot2 = pte_pgprot(pte_clrhuge(*kpte));
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split = split_large_page(address, prot, ref_prot2);
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split = split_large_page(pfn << PAGE_SHIFT, prot,
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ref_prot2);
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if (!split)
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return -ENOMEM;
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set_pte(kpte, mk_pte(split, ref_prot2));
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if (page_private(kpte_page) == 0) {
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save_page(kpte_page);
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revert_page(address, ref_prot);
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revert_page(address, pfn, ref_prot);
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}
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return 0;
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}
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*/
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int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
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{
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unsigned long phys_base_pfn = __pa_symbol(__START_KERNEL_map) >> PAGE_SHIFT;
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int err = 0;
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int i;
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break;
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/* Handle kernel mapping too which aliases part of the
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* lowmem */
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if (__pa(address) < KERNEL_TEXT_SIZE) {
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if ((pfn >= phys_base_pfn) &&
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((pfn - phys_base_pfn) < (KERNEL_TEXT_SIZE >> PAGE_SHIFT))) {
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unsigned long addr2;
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pgprot_t prot2;
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addr2 = __START_KERNEL_map + __pa(address);
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addr2 = __START_KERNEL_map + ((pfn - phys_base_pfn) << PAGE_SHIFT);
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/* Make sure the kernel mappings stay executable */
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prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
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err = __change_page_attr(addr2, pfn, prot2,
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@ -102,17 +102,15 @@ typedef struct { unsigned long pgprot; } pgprot_t;
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/* Note: __pa(&symbol_visible_to_c) should be always replaced with __pa_symbol.
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Otherwise you risk miscompilation. */
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#define __pa(x) (((unsigned long)(x)>=__START_KERNEL_map)?(unsigned long)(x) - (unsigned long)__START_KERNEL_map:(unsigned long)(x) - PAGE_OFFSET)
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#define __pa(x) ((unsigned long)(x) - PAGE_OFFSET)
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/* __pa_symbol should be used for C visible symbols.
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This seems to be the official gcc blessed way to do such arithmetic. */
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#define __pa_symbol(x) \
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({unsigned long v; \
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asm("" : "=r" (v) : "0" (x)); \
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__pa(v); })
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(v - __START_KERNEL_map); })
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#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))
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#define __boot_va(x) __va(x)
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#define __boot_pa(x) __pa(x)
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#ifdef CONFIG_FLATMEM
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#define pfn_valid(pfn) ((pfn) < end_pfn)
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#endif
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@ -19,7 +19,7 @@ extern pmd_t level2_kernel_pgt[512];
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extern pgd_t init_level4_pgt[];
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extern unsigned long __supported_pte_mask;
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#define swapper_pg_dir init_level4_pgt
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#define swapper_pg_dir ((pgd_t *)NULL)
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extern void paging_init(void);
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extern void clear_kernel_mapping(unsigned long addr, unsigned long size);
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* for zero-mapped memory areas etc..
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*/
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extern unsigned long empty_zero_page[PAGE_SIZE/sizeof(unsigned long)];
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#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
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#define ZERO_PAGE(vaddr) (pfn_to_page(__pa_symbol(&empty_zero_page) >> PAGE_SHIFT))
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#endif /* !__ASSEMBLY__ */
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