Commit 8edd7e37 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/entry: Convert INT3 exception to IDTENTRY_RAW 



Convert #BP to IDTENTRY_RAW:
  - Implement the C entry point with DEFINE_IDTENTRY_RAW
  - Invoke idtentry_enter/exit() from the function body
  - Emit the ASM stub with DECLARE_IDTENTRY_RAW
  - Remove the ASM idtentry in 64bit
  - Remove the open coded ASM entry code in 32bit
  - Fixup the XEN/PV code
  - Remove the old prototypes

No functional change.

This could be a plain IDTENTRY, but as Peter pointed out INT3 is broken
vs. the static key in the context tracking code as this static key might be
in the state of being patched and has an int3 which would recurse forever.
IDTENTRY_RAW is therefore chosen to allow addressing this issue without
lots of code churn.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarAlexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200505135313.938474960@linutronix.de
parent 0dc6cdc2

arch/x86/entry/entry_32.S

+0 −7
Original line number Diff line number Diff line
@@ -1649,13 +1649,6 @@ SYM_CODE_START(nmi) 
#endif

SYM_CODE_END(nmi)



SYM_CODE_START(int3)

	ASM_CLAC

	pushl	$0

	pushl	$do_int3

	jmp	common_exception

SYM_CODE_END(int3)



.pushsection .text, "ax"

SYM_CODE_START(rewind_stack_do_exit)

	/* Prevent any naive code from trying to unwind to our caller. */

arch/x86/entry/entry_64.S

+0 −2
Original line number Diff line number Diff line
@@ -1072,8 +1072,6 @@ apicinterrupt IRQ_WORK_VECTOR irq_work_interrupt smp_irq_work_interrupt 
 * Exception entry points.

 */



idtentry	X86_TRAP_BP		int3			do_int3				has_error_code=0



idtentry	X86_TRAP_PF		page_fault		do_page_fault			has_error_code=1



#ifdef CONFIG_X86_MCE

arch/x86/include/asm/idtentry.h

+3 −0
Original line number Diff line number Diff line
@@ -181,4 +181,7 @@ DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_SS, exc_stack_segment); 
DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_GP,	exc_general_protection);

DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_AC,	exc_alignment_check);



/* Raw exception entries which need extra work */

DECLARE_IDTENTRY_RAW(X86_TRAP_BP,	exc_int3);



#endif

arch/x86/include/asm/traps.h

+0 −3
Original line number Diff line number Diff line
@@ -13,7 +13,6 @@ 


asmlinkage void debug(void);

asmlinkage void nmi(void);

asmlinkage void int3(void);

#ifdef CONFIG_X86_64

asmlinkage void double_fault(void);

#endif
@@ -26,7 +25,6 @@ asmlinkage void machine_check(void); 
#if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV)

asmlinkage void xen_xennmi(void);

asmlinkage void xen_xendebug(void);

asmlinkage void xen_int3(void);

asmlinkage void xen_double_fault(void);

asmlinkage void xen_page_fault(void);

#ifdef CONFIG_X86_MCE
@@ -36,7 +34,6 @@ asmlinkage void xen_machine_check(void); 


dotraplinkage void do_debug(struct pt_regs *regs, long error_code);

dotraplinkage void do_nmi(struct pt_regs *regs, long error_code);

dotraplinkage void do_int3(struct pt_regs *regs, long error_code);

dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsigned long cr2);

dotraplinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address);

dotraplinkage void do_mce(struct pt_regs *regs, long error_code);

arch/x86/kernel/idt.c

+1 −1
Original line number Diff line number Diff line
@@ -60,7 +60,7 @@ static bool idt_setup_done __initdata; 
 */

static const __initconst struct idt_data early_idts[] = {

	INTG(X86_TRAP_DB,		debug),

	SYSG(X86_TRAP_BP,		int3),

	SYSG(X86_TRAP_BP,		asm_exc_int3),

#ifdef CONFIG_X86_32

	INTG(X86_TRAP_PF,		page_fault),

#endif

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