From f3ba50a7a100e91b0b13ca43190a66c1bfdb9993 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Sat, 23 Apr 2022 11:07:50 +0100 Subject: arm64: Add support for user sub-page fault probing With MTE, even if the pte allows an access, a mismatched tag somewhere within a page can still cause a fault. Select ARCH_HAS_SUBPAGE_FAULTS if MTE is enabled and implement the probe_subpage_writeable() function. Note that get_user() is sufficient for the writeable MTE check since the same tag mismatch fault would be triggered by a read. The caller of probe_subpage_writeable() will need to check the pte permissions (put_user, GUP). Signed-off-by: Catalin Marinas Cc: Will Deacon Link: https://lore.kernel.org/r/20220423100751.1870771-3-catalin.marinas@arm.com Signed-off-by: Catalin Marinas --- arch/arm64/kernel/mte.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'arch/arm64/kernel/mte.c') diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 78b3e0f8e997..35697a09926f 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -543,3 +544,32 @@ static int register_mte_tcf_preferred_sysctl(void) return 0; } subsys_initcall(register_mte_tcf_preferred_sysctl); + +/* + * Return 0 on success, the number of bytes not probed otherwise. + */ +size_t mte_probe_user_range(const char __user *uaddr, size_t size) +{ + const char __user *end = uaddr + size; + int err = 0; + char val; + + __raw_get_user(val, uaddr, err); + if (err) + return size; + + uaddr = PTR_ALIGN(uaddr, MTE_GRANULE_SIZE); + while (uaddr < end) { + /* + * A read is sufficient for mte, the caller should have probed + * for the pte write permission if required. + */ + __raw_get_user(val, uaddr, err); + if (err) + return end - uaddr; + uaddr += MTE_GRANULE_SIZE; + } + (void)val; + + return 0; +} -- cgit From 96f101a9eab479dbfbdf7713ba966f9031c9c045 Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Tue, 3 May 2022 18:02:23 +0100 Subject: arm64/mte: Make TCF0 naming and field values more standard In preparation for automatic generation of SCTLR_EL1 register definitions make the macros used to define SCTLR_EL1.TCF0 and the enumeration values it has more standard so they can be used with FIELD_PREP() via the newly defined SYS_FIELD_PREP_ helpers. Since the field also exists in SCTLR_EL2 with the same values also rename the macros to SCTLR_ELx rather than SCTLR_EL1. There should be no functional change as a result of this patch. Signed-off-by: Mark Brown Acked-by: Mark Rutland --- arch/arm64/kernel/mte.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/arm64/kernel/mte.c') diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 78b3e0f8e997..41469b69a48e 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -216,11 +216,11 @@ static void mte_update_sctlr_user(struct task_struct *task) * default order. */ if (resolved_mte_tcf & MTE_CTRL_TCF_ASYMM) - sctlr |= SCTLR_EL1_TCF0_ASYMM; + sctlr |= SYS_FIELD_PREP_ENUM(SCTLR_EL1, TCF0, ASYMM); else if (resolved_mte_tcf & MTE_CTRL_TCF_ASYNC) - sctlr |= SCTLR_EL1_TCF0_ASYNC; + sctlr |= SYS_FIELD_PREP_ENUM(SCTLR_EL1, TCF0, ASYNC); else if (resolved_mte_tcf & MTE_CTRL_TCF_SYNC) - sctlr |= SCTLR_EL1_TCF0_SYNC; + sctlr |= SYS_FIELD_PREP_ENUM(SCTLR_EL1, TCF0, SYNC); task->thread.sctlr_user = sctlr; } -- cgit From bc249e37b9334826de29111c5350c3e7a08a3969 Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Tue, 3 May 2022 18:02:24 +0100 Subject: arm64/mte: Make TCF field values and naming more standard In preparation for automatic generation of the defines for system registers make the values used for the enumeration in SCTLR_ELx.TCF suitable for use with the newly defined SYS_FIELD_PREP_ENUM helper, removing the shift from the define and using the helper to generate it on use instead. Since we only ever interact with this field in EL1 and in preparation for generation of the defines also rename from SCTLR_ELx to SCTLR_EL1. SCTLR_EL2 is not quite the same as SCTLR_EL1 so the conversion does not share the field definitions. There should be no functional change from this patch. Signed-off-by: Mark Brown Acked-by: Mark Rutland Link: https://lore.kernel.org/r/20220503170233.507788-4-broonie@kernel.org Signed-off-by: Catalin Marinas --- arch/arm64/kernel/mte.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'arch/arm64/kernel/mte.c') diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 41469b69a48e..98f5e1e13c36 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -106,7 +106,8 @@ int memcmp_pages(struct page *page1, struct page *page2) static inline void __mte_enable_kernel(const char *mode, unsigned long tcf) { /* Enable MTE Sync Mode for EL1. */ - sysreg_clear_set(sctlr_el1, SCTLR_ELx_TCF_MASK, tcf); + sysreg_clear_set(sctlr_el1, SCTLR_EL1_TCF_MASK, + SYS_FIELD_PREP(SCTLR_EL1, TCF, tcf)); isb(); pr_info_once("MTE: enabled in %s mode at EL1\n", mode); @@ -122,12 +123,12 @@ void mte_enable_kernel_sync(void) WARN_ONCE(system_uses_mte_async_or_asymm_mode(), "MTE async mode enabled system wide!"); - __mte_enable_kernel("synchronous", SCTLR_ELx_TCF_SYNC); + __mte_enable_kernel("synchronous", SCTLR_EL1_TCF_SYNC); } void mte_enable_kernel_async(void) { - __mte_enable_kernel("asynchronous", SCTLR_ELx_TCF_ASYNC); + __mte_enable_kernel("asynchronous", SCTLR_EL1_TCF_ASYNC); /* * MTE async mode is set system wide by the first PE that @@ -144,7 +145,7 @@ void mte_enable_kernel_async(void) void mte_enable_kernel_asymm(void) { if (cpus_have_cap(ARM64_MTE_ASYMM)) { - __mte_enable_kernel("asymmetric", SCTLR_ELx_TCF_ASYMM); + __mte_enable_kernel("asymmetric", SCTLR_EL1_TCF_ASYMM); /* * MTE asymm mode behaves as async mode for store -- cgit