Merge branch 'fixes' of git://git.armlinux.org.uk/~rmk/linux-arm

Pull ARM fixes from Russell King: - LPAE fixes for kernel-readonly regions - Fix for get_user_pages_fast on LPAE systems - avoid tying decompressor to a particular platform if DEBUG_LL is enabled - BUG if we attempt to return to userspace but the to-be-restored PSR value keeps us in privileged mode (defeating an issue that ftracetest found) * 'fixes' of git://git.armlinux.org.uk/~rmk/linux-arm: ARM: BUG if jumping to usermode address in kernel mode ARM: 8722/1: mm: make STRICT_KERNEL_RWX effective for LPAE ARM: 8721/1: mm: dump: check hardware RO bit for LPAE ARM: make decompressor debug output user selectable ARM: fix get_user_pages_fast
akeromi · Nov 26, 2017 · bbecb1c · bbecb1c
2 parents dec0029 + 8bafae2
commit bbecb1c
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Showing 6 changed files with 42 additions and 6 deletions.
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
@@ -1776,9 +1776,9 @@ config DEBUG_UART_8250_FLOW_CONTROL
 	default y if ARCH_EBSA110 || DEBUG_FOOTBRIDGE_COM1 || DEBUG_GEMINI || ARCH_RPC
 
 config DEBUG_UNCOMPRESS
-	bool
+	bool "Enable decompressor debugging via DEBUG_LL output"
 	depends on ARCH_MULTIPLATFORM || PLAT_SAMSUNG || ARM_SINGLE_ARMV7M
-	default y if DEBUG_LL && !DEBUG_OMAP2PLUS_UART && \
+	depends on DEBUG_LL && !DEBUG_OMAP2PLUS_UART && \
 		     (!DEBUG_TEGRA_UART || !ZBOOT_ROM) && \
 		     !DEBUG_BRCMSTB_UART
 	help

diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
@@ -518,4 +518,22 @@ THUMB(	orr	\reg , \reg , #PSR_T_BIT	)
 #endif
 	.endm
 
+	.macro	bug, msg, line
+#ifdef CONFIG_THUMB2_KERNEL
+1:	.inst	0xde02
+#else
+1:	.inst	0xe7f001f2
+#endif
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+	.pushsection .rodata.str, "aMS", %progbits, 1
+2:	.asciz	"\msg"
+	.popsection
+	.pushsection __bug_table, "aw"
+	.align	2
+	.word	1b, 2b
+	.hword	\line
+	.popsection
+#endif
+	.endm
+
 #endif /* __ASM_ASSEMBLER_H__ */
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
@@ -232,6 +232,18 @@ static inline pte_t *pmd_page_vaddr(pmd_t pmd)
 #define pte_valid_user(pte)	\
 	(pte_valid(pte) && pte_isset((pte), L_PTE_USER) && pte_young(pte))
 
+static inline bool pte_access_permitted(pte_t pte, bool write)
+{
+	pteval_t mask = L_PTE_PRESENT | L_PTE_USER;
+	pteval_t needed = mask;
+
+	if (write)
+		mask |= L_PTE_RDONLY;
+
+	return (pte_val(pte) & mask) == needed;
+}
+#define pte_access_permitted pte_access_permitted
+
 #if __LINUX_ARM_ARCH__ < 6
 static inline void __sync_icache_dcache(pte_t pteval)
 {

diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
@@ -300,6 +300,8 @@
 	mov	r2, sp
 	ldr	r1, [r2, #\offset + S_PSR]	@ get calling cpsr
 	ldr	lr, [r2, #\offset + S_PC]!	@ get pc
+	tst	r1, #0xcf
+	bne	1f
 	msr	spsr_cxsf, r1			@ save in spsr_svc
 #if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)
 	@ We must avoid clrex due to Cortex-A15 erratum #830321
@@ -314,6 +316,7 @@
 						@ after ldm {}^
 	add	sp, sp, #\offset + PT_REGS_SIZE
 	movs	pc, lr				@ return & move spsr_svc into cpsr
+1:	bug	"Returning to usermode but unexpected PSR bits set?", \@
 #elif defined(CONFIG_CPU_V7M)
 	@ V7M restore.
 	@ Note that we don't need to do clrex here as clearing the local
@@ -329,6 +332,8 @@
 	ldr	r1, [sp, #\offset + S_PSR]	@ get calling cpsr
 	ldr	lr, [sp, #\offset + S_PC]	@ get pc
 	add	sp, sp, #\offset + S_SP
+	tst	r1, #0xcf
+	bne	1f
 	msr	spsr_cxsf, r1			@ save in spsr_svc
 
 	@ We must avoid clrex due to Cortex-A15 erratum #830321
@@ -341,6 +346,7 @@
 	.endif
 	add	sp, sp, #PT_REGS_SIZE - S_SP
 	movs	pc, lr				@ return & move spsr_svc into cpsr
+1:	bug	"Returning to usermode but unexpected PSR bits set?", \@
 #endif	/* !CONFIG_THUMB2_KERNEL */
 	.endm
 

diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c
@@ -129,8 +129,8 @@ static const struct prot_bits section_bits[] = {
 		.val	= PMD_SECT_USER,
 		.set	= "USR",
 	}, {
-		.mask	= L_PMD_SECT_RDONLY,
-		.val	= L_PMD_SECT_RDONLY,
+		.mask	= L_PMD_SECT_RDONLY | PMD_SECT_AP2,
+		.val	= L_PMD_SECT_RDONLY | PMD_SECT_AP2,
 		.set	= "ro",
 		.clear	= "RW",
 #elif __LINUX_ARM_ARCH__ >= 6

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
@@ -629,8 +629,8 @@ static struct section_perm ro_perms[] = {
 		.start  = (unsigned long)_stext,
 		.end    = (unsigned long)__init_begin,
 #ifdef CONFIG_ARM_LPAE
-		.mask   = ~L_PMD_SECT_RDONLY,
-		.prot   = L_PMD_SECT_RDONLY,
+		.mask   = ~(L_PMD_SECT_RDONLY | PMD_SECT_AP2),
+		.prot   = L_PMD_SECT_RDONLY | PMD_SECT_AP2,
 #else
 		.mask   = ~(PMD_SECT_APX | PMD_SECT_AP_WRITE),
 		.prot   = PMD_SECT_APX | PMD_SECT_AP_WRITE,