Commit ae755b5a authored by Juergen Gross's avatar Juergen Gross Committed by Borislav Petkov
Browse files

x86/paravirt: Switch iret pvops to ALTERNATIVE 



The iret paravirt op is rather special as it is using a jmp instead
of a call instruction. Switch it to ALTERNATIVE.

Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210311142319.4723-12-jgross@suse.com
parent 0b8d366a

arch/x86/include/asm/paravirt.h

+3 −3
Original line number Diff line number Diff line
@@ -747,9 +747,9 @@ extern void default_banner(void); 
#define PARA_INDIRECT(addr)	*addr(%rip)



#define INTERRUPT_RETURN						\

	PARA_SITE(PARA_PATCH(PV_CPU_iret),				\

	ANNOTATE_RETPOLINE_SAFE;					\

		  jmp PARA_INDIRECT(pv_ops+PV_CPU_iret);)

	ALTERNATIVE_TERNARY("jmp *paravirt_iret(%rip);",		\

		X86_FEATURE_XENPV, "jmp xen_iret;", "jmp native_iret;")



#ifdef CONFIG_DEBUG_ENTRY

#define SAVE_FLAGS(clobbers)                                        \

arch/x86/include/asm/paravirt_types.h

+1 −4
Original line number Diff line number Diff line
@@ -151,10 +151,6 @@ struct pv_cpu_ops { 


	u64 (*read_pmc)(int counter);



	/* Normal iret.  Jump to this with the standard iret stack

	   frame set up. */

	void (*iret)(void);



	void (*start_context_switch)(struct task_struct *prev);

	void (*end_context_switch)(struct task_struct *next);

#endif
@@ -294,6 +290,7 @@ struct paravirt_patch_template { 


extern struct pv_info pv_info;

extern struct paravirt_patch_template pv_ops;

extern void (*paravirt_iret)(void);



#define PARAVIRT_PATCH(x)					\

	(offsetof(struct paravirt_patch_template, x) / sizeof(void *))

arch/x86/kernel/asm-offsets.c

+0 −5
Original line number Diff line number Diff line
@@ -61,11 +61,6 @@ static void __used common(void) 
	OFFSET(IA32_RT_SIGFRAME_sigcontext, rt_sigframe_ia32, uc.uc_mcontext);

#endif



#ifdef CONFIG_PARAVIRT_XXL

	BLANK();

	OFFSET(PV_CPU_iret, paravirt_patch_template, cpu.iret);

#endif



#ifdef CONFIG_XEN

	BLANK();

	OFFSET(XEN_vcpu_info_mask, vcpu_info, evtchn_upcall_mask);

arch/x86/kernel/paravirt.c

+2 −24
Original line number Diff line number Diff line
@@ -86,25 +86,6 @@ u64 notrace _paravirt_ident_64(u64 x) 
{

	return x;

}



static unsigned paravirt_patch_jmp(void *insn_buff, const void *target,

				   unsigned long addr, unsigned len)

{

	struct branch *b = insn_buff;

	unsigned long delta = (unsigned long)target - (addr+5);



	if (len < 5) {

#ifdef CONFIG_RETPOLINE

		WARN_ONCE(1, "Failing to patch indirect JMP in %ps\n", (void *)addr);

#endif

		return len;	/* call too long for patch site */

	}



	b->opcode = 0xe9;	/* jmp */

	b->delta = delta;



	return 5;

}

#endif



DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);
@@ -136,9 +117,6 @@ unsigned paravirt_patch_default(u8 type, void *insn_buff, 
	else if (opfunc == _paravirt_ident_64)

		ret = paravirt_patch_ident_64(insn_buff, len);



	else if (type == PARAVIRT_PATCH(cpu.iret))

		/* If operation requires a jmp, then jmp */

		ret = paravirt_patch_jmp(insn_buff, opfunc, addr, len);

#endif

	else

		/* Otherwise call the function. */
@@ -313,8 +291,6 @@ struct paravirt_patch_template pv_ops = { 


	.cpu.load_sp0		= native_load_sp0,



	.cpu.iret		= native_iret,



#ifdef CONFIG_X86_IOPL_IOPERM

	.cpu.invalidate_io_bitmap	= native_tss_invalidate_io_bitmap,

	.cpu.update_io_bitmap		= native_tss_update_io_bitmap,
@@ -419,6 +395,8 @@ struct paravirt_patch_template pv_ops = { 
NOKPROBE_SYMBOL(native_get_debugreg);

NOKPROBE_SYMBOL(native_set_debugreg);

NOKPROBE_SYMBOL(native_load_idt);



void (*paravirt_iret)(void) = native_iret;

#endif



EXPORT_SYMBOL(pv_ops);

arch/x86/xen/enlighten_pv.c

+1 −2
Original line number Diff line number Diff line
@@ -1070,8 +1070,6 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = { 


	.read_pmc = xen_read_pmc,



	.iret = xen_iret,



	.load_tr_desc = paravirt_nop,

	.set_ldt = xen_set_ldt,

	.load_gdt = xen_load_gdt,
@@ -1235,6 +1233,7 @@ asmlinkage __visible void __init xen_start_kernel(void) 
	pv_info = xen_info;

	pv_ops.init.patch = paravirt_patch_default;

	pv_ops.cpu = xen_cpu_ops;

	paravirt_iret = xen_iret;

	xen_init_irq_ops();



	/*