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c966483930
Two functions in the 32-bit doublefault code are lacking a prototype:
arch/x86/kernel/doublefault_32.c:23:36: error: no previous prototype for 'doublefault_shim' [-Werror=missing-prototypes]
23 | asmlinkage noinstr void __noreturn doublefault_shim(void)
| ^~~~~~~~~~~~~~~~
arch/x86/kernel/doublefault_32.c:114:6: error: no previous prototype for 'doublefault_init_cpu_tss' [-Werror=missing-prototypes]
114 | void doublefault_init_cpu_tss(void)
The first one is only called from assembler, while the second one is
declared in doublefault.h, but this file is not included.
Include the header file and add the other declaration there as well.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://lore.kernel.org/all/20230516193549.544673-8-arnd%40kernel.org
130 lines
3.4 KiB
C
130 lines
3.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/sched/debug.h>
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#include <linux/init_task.h>
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#include <linux/fs.h>
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#include <linux/uaccess.h>
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#include <asm/processor.h>
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#include <asm/desc.h>
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#include <asm/traps.h>
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#include <asm/doublefault.h>
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#define ptr_ok(x) ((x) > PAGE_OFFSET && (x) < PAGE_OFFSET + MAXMEM)
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#define TSS(x) this_cpu_read(cpu_tss_rw.x86_tss.x)
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static void set_df_gdt_entry(unsigned int cpu);
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/*
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* Called by double_fault with CR0.TS and EFLAGS.NT cleared. The CPU thinks
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* we're running the doublefault task. Cannot return.
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*/
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asmlinkage noinstr void __noreturn doublefault_shim(void)
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{
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unsigned long cr2;
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struct pt_regs regs;
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BUILD_BUG_ON(sizeof(struct doublefault_stack) != PAGE_SIZE);
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cr2 = native_read_cr2();
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/* Reset back to the normal kernel task. */
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force_reload_TR();
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set_df_gdt_entry(smp_processor_id());
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trace_hardirqs_off();
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/*
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* Fill in pt_regs. A downside of doing this in C is that the unwinder
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* won't see it (no ENCODE_FRAME_POINTER), so a nested stack dump
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* won't successfully unwind to the source of the double fault.
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* The main dump from exc_double_fault() is fine, though, since it
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* uses these regs directly.
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*
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* If anyone ever cares, this could be moved to asm.
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*/
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regs.ss = TSS(ss);
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regs.__ssh = 0;
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regs.sp = TSS(sp);
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regs.flags = TSS(flags);
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regs.cs = TSS(cs);
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/* We won't go through the entry asm, so we can leave __csh as 0. */
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regs.__csh = 0;
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regs.ip = TSS(ip);
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regs.orig_ax = 0;
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regs.gs = TSS(gs);
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regs.__gsh = 0;
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regs.fs = TSS(fs);
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regs.__fsh = 0;
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regs.es = TSS(es);
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regs.__esh = 0;
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regs.ds = TSS(ds);
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regs.__dsh = 0;
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regs.ax = TSS(ax);
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regs.bp = TSS(bp);
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regs.di = TSS(di);
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regs.si = TSS(si);
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regs.dx = TSS(dx);
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regs.cx = TSS(cx);
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regs.bx = TSS(bx);
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exc_double_fault(®s, 0, cr2);
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/*
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* x86_32 does not save the original CR3 anywhere on a task switch.
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* This means that, even if we wanted to return, we would need to find
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* some way to reconstruct CR3. We could make a credible guess based
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* on cpu_tlbstate, but that would be racy and would not account for
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* PTI.
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*/
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panic("cannot return from double fault\n");
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}
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DEFINE_PER_CPU_PAGE_ALIGNED(struct doublefault_stack, doublefault_stack) = {
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.tss = {
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/*
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* No sp0 or ss0 -- we never run CPL != 0 with this TSS
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* active. sp is filled in later.
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*/
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.ldt = 0,
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.io_bitmap_base = IO_BITMAP_OFFSET_INVALID,
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.ip = (unsigned long) asm_exc_double_fault,
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.flags = X86_EFLAGS_FIXED,
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.es = __USER_DS,
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.cs = __KERNEL_CS,
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.ss = __KERNEL_DS,
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.ds = __USER_DS,
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.fs = __KERNEL_PERCPU,
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.gs = 0,
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.__cr3 = __pa_nodebug(swapper_pg_dir),
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},
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};
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static void set_df_gdt_entry(unsigned int cpu)
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{
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/* Set up doublefault TSS pointer in the GDT */
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__set_tss_desc(cpu, GDT_ENTRY_DOUBLEFAULT_TSS,
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&get_cpu_entry_area(cpu)->doublefault_stack.tss);
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}
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void doublefault_init_cpu_tss(void)
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{
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unsigned int cpu = smp_processor_id();
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struct cpu_entry_area *cea = get_cpu_entry_area(cpu);
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/*
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* The linker isn't smart enough to initialize percpu variables that
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* point to other places in percpu space.
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*/
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this_cpu_write(doublefault_stack.tss.sp,
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(unsigned long)&cea->doublefault_stack.stack +
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sizeof(doublefault_stack.stack));
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set_df_gdt_entry(cpu);
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}
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