Merge "UPSTREAM: arm64: entry: Add fake CPU feature for unmapping the kernel at EL0" (a4fff4d0) · Commits · e / devices / android_kernel_fairphone_FP3

arch/arm64/include/asm/cpucaps.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -35,6 +35,8 @@
		#define ARM64_HYP_OFFSET_LOW 14
		#define ARM64_MISMATCHED_CACHE_LINE_SIZE 15

		#define ARM64_NCAPS 16
		#define ARM64_UNMAP_KERNEL_AT_EL0 16

		#define ARM64_NCAPS 17

		#endif /* __ASM_CPUCAPS_H */

+2 −1

Original line number	Diff line number	Diff line
		@@ -35,7 +35,8 @@ typedef struct {

		static inline bool arm64_kernel_unmapped_at_el0(void)
		{
		return IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0);
		return IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0) &&
		cpus_have_cap(ARM64_UNMAP_KERNEL_AT_EL0);
		}

		extern void paging_init(void);

+41 −0

Original line number	Diff line number	Diff line
		@@ -748,6 +748,40 @@ static bool hyp_offset_low(const struct arm64_cpu_capabilities *entry,
		return idmap_addr > GENMASK(VA_BITS - 2, 0) && !is_kernel_in_hyp_mode();
		}

		#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
		static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */

		static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
		int __unused)
		{
		/* Forced on command line? */
		if (__kpti_forced) {
		pr_info_once("kernel page table isolation forced %s by command line option\n",
		__kpti_forced > 0 ? "ON" : "OFF");
		return __kpti_forced > 0;
		}

		/* Useful for KASLR robustness */
		if (IS_ENABLED(CONFIG_RANDOMIZE_BASE))
		return true;

		return false;
		}

		static int __init parse_kpti(char *str)
		{
		bool enabled;
		int ret = strtobool(str, &enabled);

		if (ret)
		return ret;

		__kpti_forced = enabled ? 1 : -1;
		return 0;
		}
		__setup("kpti=", parse_kpti);
		#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */

		static const struct arm64_cpu_capabilities arm64_features[] = {
		{
		.desc = "GIC system register CPU interface",
		@@ -831,6 +865,13 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
		.def_scope = SCOPE_SYSTEM,
		.matches = hyp_offset_low,
		},
		#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
		{
		.capability = ARM64_UNMAP_KERNEL_AT_EL0,
		.def_scope = SCOPE_SYSTEM,
		.matches = unmap_kernel_at_el0,
		},
		#endif
		{},
		};

+5 −4

Original line number	Diff line number	Diff line
		@@ -74,6 +74,7 @@
		.macro kernel_ventry, el, label, regsize = 64
		.align 7
		#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
		alternative_if ARM64_UNMAP_KERNEL_AT_EL0
		.if \el == 0
		.if \regsize == 64
		mrs x30, tpidrro_el0
		@@ -82,6 +83,7 @@
		mov x30, xzr
		.endif
		.endif
		alternative_else_nop_endif
		#endif

		sub sp, sp, #S_FRAME_SIZE
		@@ -269,10 +271,9 @@ alternative_else_nop_endif
		ldr lr, [sp, #S_LR]
		add sp, sp, #S_FRAME_SIZE // restore sp

		#ifndef CONFIG_UNMAP_KERNEL_AT_EL0
		eret
		#else
		.if \el == 0
		alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0
		#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
		bne 4f
		msr far_el1, x30
		tramp_alias x30, tramp_exit_native
		@@ -280,10 +281,10 @@ alternative_else_nop_endif
		4:
		tramp_alias x30, tramp_exit_compat
		br x30
		#endif
		.else
		eret
		.endif
		#endif
		.endm

		.macro irq_stack_entry