Commit c06ac277 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/security: change link stack flush state to the flush type enum 



Prepare to allow for hardware link stack flushing by using the
none/sw/hw type, same as the count cache state.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200609070610.846703-3-npiggin@gmail.com
parent 1026798c

arch/powerpc/kernel/security.c

+5 −5
Original line number Diff line number Diff line
@@ -27,7 +27,7 @@ enum branch_cache_flush_type { 
	BRANCH_CACHE_FLUSH_HW	= 0x4,

};

static enum branch_cache_flush_type count_cache_flush_type = BRANCH_CACHE_FLUSH_NONE;

static bool link_stack_flush_enabled;

static enum branch_cache_flush_type link_stack_flush_type = BRANCH_CACHE_FLUSH_NONE;



bool barrier_nospec_enabled;

static bool no_nospec;
@@ -219,7 +219,7 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, c 
		if (ccd)

			seq_buf_printf(&s, "Indirect branch cache disabled");



		if (link_stack_flush_enabled)

		if (link_stack_flush_type == BRANCH_CACHE_FLUSH_SW)

			seq_buf_printf(&s, ", Software link stack flush");



	} else if (count_cache_flush_type != BRANCH_CACHE_FLUSH_NONE) {
@@ -228,7 +228,7 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, c 
		if (count_cache_flush_type == BRANCH_CACHE_FLUSH_HW)

			seq_buf_printf(&s, " (hardware accelerated)");



		if (link_stack_flush_enabled)

		if (link_stack_flush_type == BRANCH_CACHE_FLUSH_SW)

			seq_buf_printf(&s, ", Software link stack flush");



	} else if (btb_flush_enabled) {
@@ -447,7 +447,7 @@ static void toggle_branch_cache_flush(bool enable) 
				       ppc_inst(PPC_INST_NOP));

#endif

		pr_info("link-stack-flush: software flush disabled.\n");

		link_stack_flush_enabled = false;

		link_stack_flush_type = BRANCH_CACHE_FLUSH_NONE;

		no_count_cache_flush();

		return;

	}
@@ -463,7 +463,7 @@ static void toggle_branch_cache_flush(bool enable) 
#endif



	pr_info("link-stack-flush: software flush enabled.\n");

	link_stack_flush_enabled = true;

	link_stack_flush_type = BRANCH_CACHE_FLUSH_SW;



	// If we just need to flush the link stack, patch an early return

	if (!security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE)) {

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