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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 11:19:37 +00:00
[PATCH] x86_64: Move int 3 handler to debug stack and allow to increase it.
This - switches the INT3 handler to run on an IST stack (to cope with breakpoints set by a kernel debugger on places where the kernel's %gs base hasn't been set up, yet); the IST stack used is shared with the INT1 handler's [AK: this also allows setting a kprobe on the interrupt/exception entry points] - allows nesting of INT1/INT3 handlers so that one can, with a kernel debugger, debug (at least) the user-mode portions of the INT1/INT3 handling; the nesting isn't actively enabled here since a kernel- debugger-free kernel doesn't need it Signed-Off-By: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
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ed8388a5d9
commit
b556b35e98
8 changed files with 95 additions and 22 deletions
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@ -64,5 +64,9 @@ int main(void)
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DEFINE(pbe_address, offsetof(struct pbe, address));
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DEFINE(pbe_orig_address, offsetof(struct pbe, orig_address));
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DEFINE(pbe_next, offsetof(struct pbe, next));
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BLANK();
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#if DEBUG_STKSZ > EXCEPTION_STKSZ
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DEFINE(DEBUG_IST, DEBUG_STACK);
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#endif
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return 0;
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}
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@ -673,7 +673,10 @@ ENTRY(spurious_interrupt)
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/* error code is on the stack already */
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/* handle NMI like exceptions that can happen everywhere */
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.macro paranoidentry sym
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#ifndef DEBUG_IST
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# define DEBUG_IST 0
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#endif
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.macro paranoidentry sym, ist=0
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SAVE_ALL
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cld
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movl $1,%ebx
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@ -683,10 +686,20 @@ ENTRY(spurious_interrupt)
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js 1f
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swapgs
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xorl %ebx,%ebx
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1: movq %rsp,%rdi
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1:
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.if \ist
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movq %gs:pda_data_offset, %rbp
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.endif
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movq %rsp,%rdi
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movq ORIG_RAX(%rsp),%rsi
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movq $-1,ORIG_RAX(%rsp)
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.if \ist
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subq $EXCEPTION_STACK_SIZE, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
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.endif
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call \sym
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.if \ist
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addq $EXCEPTION_STACK_SIZE, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
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.endif
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cli
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.endm
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@ -904,7 +917,7 @@ KPROBE_ENTRY(debug)
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INTR_FRAME
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pushq $0
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CFI_ADJUST_CFA_OFFSET 8
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paranoidentry do_debug
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paranoidentry do_debug, DEBUG_IST
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jmp paranoid_exit
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CFI_ENDPROC
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.previous .text
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@ -959,7 +972,12 @@ paranoid_schedule:
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CFI_ENDPROC
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KPROBE_ENTRY(int3)
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zeroentry do_int3
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INTR_FRAME
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pushq $0
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CFI_ADJUST_CFA_OFFSET 8
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paranoidentry do_int3, DEBUG_IST
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jmp paranoid_exit
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CFI_ENDPROC
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.previous .text
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ENTRY(overflow)
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@ -145,7 +145,7 @@ void pda_init(int cpu)
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pda->irqstackptr += IRQSTACKSIZE-64;
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}
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char boot_exception_stacks[N_EXCEPTION_STACKS * EXCEPTION_STKSZ]
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char boot_exception_stacks[(N_EXCEPTION_STACKS - 2) * EXCEPTION_STKSZ + DEBUG_STKSZ]
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__attribute__((section(".bss.page_aligned")));
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/* May not be marked __init: used by software suspend */
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@ -236,13 +236,27 @@ void __cpuinit cpu_init (void)
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*/
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for (v = 0; v < N_EXCEPTION_STACKS; v++) {
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if (cpu) {
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estacks = (char *)__get_free_pages(GFP_ATOMIC,
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EXCEPTION_STACK_ORDER);
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static const unsigned int order[N_EXCEPTION_STACKS] = {
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[0 ... N_EXCEPTION_STACKS - 1] = EXCEPTION_STACK_ORDER,
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[DEBUG_STACK - 1] = DEBUG_STACK_ORDER
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};
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estacks = (char *)__get_free_pages(GFP_ATOMIC, order[v]);
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if (!estacks)
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panic("Cannot allocate exception stack %ld %d\n",
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v, cpu);
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}
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estacks += EXCEPTION_STKSZ;
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switch (v + 1) {
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#if DEBUG_STKSZ > EXCEPTION_STKSZ
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case DEBUG_STACK:
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cpu_pda[cpu].debugstack = (unsigned long)estacks;
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estacks += DEBUG_STKSZ;
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break;
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#endif
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default:
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estacks += EXCEPTION_STKSZ;
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break;
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}
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t->ist[v] = (unsigned long)estacks;
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}
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@ -121,19 +121,31 @@ int printk_address(unsigned long address)
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static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
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unsigned *usedp, const char **idp)
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{
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static const char ids[N_EXCEPTION_STACKS][8] = {
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static char ids[][8] = {
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[DEBUG_STACK - 1] = "#DB",
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[NMI_STACK - 1] = "NMI",
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[DOUBLEFAULT_STACK - 1] = "#DF",
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[STACKFAULT_STACK - 1] = "#SS",
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[MCE_STACK - 1] = "#MC",
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#if DEBUG_STKSZ > EXCEPTION_STKSZ
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[N_EXCEPTION_STACKS ... N_EXCEPTION_STACKS + DEBUG_STKSZ / EXCEPTION_STKSZ - 2] = "#DB[?]"
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#endif
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};
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unsigned k;
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for (k = 0; k < N_EXCEPTION_STACKS; k++) {
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unsigned long end;
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end = per_cpu(init_tss, cpu).ist[k];
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switch (k + 1) {
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#if DEBUG_STKSZ > EXCEPTION_STKSZ
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case DEBUG_STACK:
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end = cpu_pda[cpu].debugstack + DEBUG_STKSZ;
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break;
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#endif
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default:
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end = per_cpu(init_tss, cpu).ist[k];
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break;
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}
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if (stack >= end)
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continue;
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if (stack >= end - EXCEPTION_STKSZ) {
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@ -143,6 +155,22 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
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*idp = ids[k];
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return (unsigned long *)end;
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}
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#if DEBUG_STKSZ > EXCEPTION_STKSZ
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if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
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unsigned j = N_EXCEPTION_STACKS - 1;
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do {
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++j;
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end -= EXCEPTION_STKSZ;
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ids[j][4] = '1' + (j - N_EXCEPTION_STACKS);
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} while (stack < end - EXCEPTION_STKSZ);
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if (*usedp & (1U << j))
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break;
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*usedp |= 1U << j;
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*idp = ids[j];
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return (unsigned long *)end;
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}
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#endif
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}
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return NULL;
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}
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@ -613,6 +641,7 @@ asmlinkage void default_do_nmi(struct pt_regs *regs)
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io_check_error(reason, regs);
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}
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/* runs on IST stack. */
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asmlinkage void __kprobes do_int3(struct pt_regs * regs, long error_code)
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{
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if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP) == NOTIFY_STOP) {
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@ -894,7 +923,7 @@ void __init trap_init(void)
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set_intr_gate(0,÷_error);
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set_intr_gate_ist(1,&debug,DEBUG_STACK);
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set_intr_gate_ist(2,&nmi,NMI_STACK);
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set_system_gate(3,&int3);
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set_system_gate_ist(3,&int3,DEBUG_STACK); /* int3 can be called from all */
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set_system_gate(4,&overflow); /* int4 can be called from all */
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set_intr_gate(5,&bounds);
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set_intr_gate(6,&invalid_op);
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@ -114,6 +114,11 @@ static inline void set_system_gate(int nr, void *func)
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_set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 3, 0);
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}
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static inline void set_system_gate_ist(int nr, void *func, unsigned ist)
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{
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_set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 3, ist);
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}
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static inline void set_tssldt_descriptor(void *ptr, unsigned long tss, unsigned type,
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unsigned size)
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{
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@ -14,13 +14,18 @@
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#define PHYSICAL_PAGE_MASK (~(PAGE_SIZE-1) & __PHYSICAL_MASK)
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#define THREAD_ORDER 1
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#ifdef __ASSEMBLY__
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#define THREAD_SIZE (1 << (PAGE_SHIFT + THREAD_ORDER))
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#else
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#define THREAD_SIZE (1UL << (PAGE_SHIFT + THREAD_ORDER))
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#endif
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#define THREAD_SIZE (PAGE_SIZE << THREAD_ORDER)
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#define CURRENT_MASK (~(THREAD_SIZE-1))
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#define EXCEPTION_STACK_ORDER 0
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#define EXCEPTION_STKSZ (PAGE_SIZE << EXCEPTION_STACK_ORDER)
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#define DEBUG_STACK_ORDER EXCEPTION_STACK_ORDER
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#define DEBUG_STKSZ (PAGE_SIZE << DEBUG_STACK_ORDER)
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#define IRQSTACK_ORDER 2
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#define IRQSTACKSIZE (PAGE_SIZE << IRQSTACK_ORDER)
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#define LARGE_PAGE_MASK (~(LARGE_PAGE_SIZE-1))
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#define LARGE_PAGE_SIZE (1UL << PMD_SHIFT)
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@ -5,6 +5,7 @@
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#include <linux/stddef.h>
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#include <linux/types.h>
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#include <linux/cache.h>
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#include <asm/page.h>
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/* Per processor datastructure. %gs points to it while the kernel runs */
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struct x8664_pda {
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unsigned long data_offset; /* Per cpu data offset from linker address */
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unsigned long kernelstack; /* top of kernel stack for current */
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unsigned long oldrsp; /* user rsp for system call */
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#if DEBUG_STKSZ > EXCEPTION_STKSZ
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unsigned long debugstack; /* #DB/#BP stack. */
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#endif
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int irqcount; /* Irq nesting counter. Starts with -1 */
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int cpunumber; /* Logical CPU number */
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char *irqstackptr; /* top of irqstack */
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@ -23,10 +27,6 @@ struct x8664_pda {
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unsigned apic_timer_irqs;
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} ____cacheline_aligned_in_smp;
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#define IRQSTACK_ORDER 2
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#define IRQSTACKSIZE (PAGE_SIZE << IRQSTACK_ORDER)
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extern struct x8664_pda cpu_pda[];
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/*
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@ -273,8 +273,6 @@ struct thread_struct {
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#define DEBUG_STACK 4
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#define MCE_STACK 5
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#define N_EXCEPTION_STACKS 5 /* hw limit: 7 */
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#define EXCEPTION_STKSZ (PAGE_SIZE << EXCEPTION_STACK_ORDER)
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#define EXCEPTION_STACK_ORDER 0
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#define start_thread(regs,new_rip,new_rsp) do { \
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asm volatile("movl %0,%%fs; movl %0,%%es; movl %0,%%ds": :"r" (0)); \
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