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x86/entry: Convert double fault exception to IDTENTRY_DF

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Convert #DF to IDTENTRY_DF
  - Implement the C entry point with DEFINE_IDTENTRY_DF
  - Emit the ASM stub with DECLARE_IDTENTRY_DF on 64bit
  - Remove the ASM idtentry in 64bit
  - Adjust the 32bit shim code
  - Fixup the XEN/PV code
  - Remove the old prototypes

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200505135315.583415264@linutronix.de
This commit is contained in:
Thomas Gleixner
2020-02-25 23:33:31 +01:00
parent 6a8dfa8e40
commit c29c775a55
9 changed files with 29 additions and 30 deletions
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10
arch/x86/kernel/doublefault_32.c
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@@ -10,7 +10,6 @@
#include <asm/desc.h>
#include <asm/traps.h>
extern void double_fault(void);
#define ptr_ok(x) ((x) > PAGE_OFFSET && (x) < PAGE_OFFSET + MAXMEM)
#define TSS(x) this_cpu_read(cpu_tss_rw.x86_tss.x)
@@ -21,7 +20,7 @@ static void set_df_gdt_entry(unsigned int cpu);
* Called by double_fault with CR0.TS and EFLAGS.NT cleared. The CPU thinks
* we're running the doublefault task. Cannot return.
*/
asmlinkage notrace void __noreturn doublefault_shim(void)
asmlinkage noinstr void __noreturn doublefault_shim(void)
{
unsigned long cr2;
struct pt_regs regs;
@@ -40,7 +39,7 @@ asmlinkage notrace void __noreturn doublefault_shim(void)
* Fill in pt_regs. A downside of doing this in C is that the unwinder
* won't see it (no ENCODE_FRAME_POINTER), so a nested stack dump
* won't successfully unwind to the source of the double fault.
* The main dump from do_double_fault() is fine, though, since it
* The main dump from exc_double_fault() is fine, though, since it
* uses these regs directly.
*
* If anyone ever cares, this could be moved to asm.
@@ -70,7 +69,7 @@ asmlinkage notrace void __noreturn doublefault_shim(void)
regs.cx = TSS(cx);
regs.bx = TSS(bx);
do_double_fault(&regs, 0, cr2);
exc_double_fault(&regs, 0, cr2);
/*
* x86_32 does not save the original CR3 anywhere on a task switch.
@@ -84,7 +83,6 @@ asmlinkage notrace void __noreturn doublefault_shim(void)
*/
panic("cannot return from double fault\n");
}
NOKPROBE_SYMBOL(doublefault_shim);
DEFINE_PER_CPU_PAGE_ALIGNED(struct doublefault_stack, doublefault_stack) = {
.tss = {
@@ -95,7 +93,7 @@ DEFINE_PER_CPU_PAGE_ALIGNED(struct doublefault_stack, doublefault_stack) = {
.ldt = 0,
.io_bitmap_base = IO_BITMAP_OFFSET_INVALID,
.ip = (unsigned long) double_fault,
.ip = (unsigned long) asm_exc_double_fault,
.flags = X86_EFLAGS_FIXED,
.es = __USER_DS,
.cs = __KERNEL_CS,