If a Cortex-A715 cpu sees a page mapping permissions change from executable
to non-executable, it may corrupt the ESR_ELx and FAR_ELx registers, on the
next instruction abort caused by permission fault.
Only user-space does executable to non-executable permission transition via
mprotect() system call which calls ptep_modify_prot_start() and ptep_modify
_prot_commit() helpers, while changing the page mapping. The platform code
can override these helpers via __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION.
Work around the problem via doing a break-before-make TLB invalidation, for
all executable user space mappings, that go through mprotect() system call.
This overrides ptep_modify_prot_start() and ptep_modify_prot_commit(), via
defining HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION on the platform thus giving
an opportunity to intercept user space exec mappings, and do the necessary
TLB invalidation. Similar interceptions are also implemented for HugeTLB.
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Reviewed-by: Catalin Marinas <[email protected]>
Signed-off-by: Anshuman Khandual <[email protected]>
---
This applies on v6.2-rc2. This has been tested on the model with 0x411FD4D1
as the MIDR_EL1 value for Cortex-A715, along with a non Cortex-A715 CPU as
well, triggering both paths.
Changes in V4:
- Folded in CONFIG_ARM64_ERRATUM_2645198 related changes from Lukas Bulwahn
https://lore.kernel.org/all/[email protected]/
Changes in V3:
https://lore.kernel.org/all/[email protected]/
Documentation/arm64/silicon-errata.rst | 2 ++
arch/arm64/Kconfig | 16 ++++++++++++++++
arch/arm64/include/asm/hugetlb.h | 9 +++++++++
arch/arm64/include/asm/pgtable.h | 9 +++++++++
arch/arm64/kernel/cpu_errata.c | 7 +++++++
arch/arm64/mm/hugetlbpage.c | 21 +++++++++++++++++++++
arch/arm64/mm/mmu.c | 21 +++++++++++++++++++++
arch/arm64/tools/cpucaps | 1 +
8 files changed, 86 insertions(+)
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index 808ade4cc008..ec5f889d7681 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -120,6 +120,8 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A710 | #2224489 | ARM64_ERRATUM_2224489 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-A715 | #2645198 | ARM64_ERRATUM_2645198 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-X2 | #2119858 | ARM64_ERRATUM_2119858 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-X2 | #2224489 | ARM64_ERRATUM_2224489 |
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 03934808b2ed..cf6d1cd8b6dc 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -972,6 +972,22 @@ config ARM64_ERRATUM_2457168
If unsure, say Y.
+config ARM64_ERRATUM_2645198
+ bool "Cortex-A715: 2645198: Workaround possible [ESR|FAR]_ELx corruption"
+ default y
+ help
+ This option adds the workaround for ARM Cortex-A715 erratum 2645198.
+
+ If a Cortex-A715 cpu sees a page mapping permissions change from executable
+ to non-executable, it may corrupt the ESR_ELx and FAR_ELx registers on the
+ next instruction abort caused by permission fault.
+
+ Only user-space does executable to non-executable permission transition via
+ mprotect() system call. Workaround the problem by doing a break-before-make
+ TLB invalidation, for all changes to executable user space mappings.
+
+ If unsure, say Y.
+
config CAVIUM_ERRATUM_22375
bool "Cavium erratum 22375, 24313"
default y
diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
index d20f5da2d76f..6a4a1ab8eb23 100644
--- a/arch/arm64/include/asm/hugetlb.h
+++ b/arch/arm64/include/asm/hugetlb.h
@@ -49,6 +49,15 @@ extern pte_t huge_ptep_get(pte_t *ptep);
void __init arm64_hugetlb_cma_reserve(void);
+#define huge_ptep_modify_prot_start huge_ptep_modify_prot_start
+extern pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep);
+
+#define huge_ptep_modify_prot_commit huge_ptep_modify_prot_commit
+extern void huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ pte_t old_pte, pte_t new_pte);
+
#include <asm-generic/hugetlb.h>
#endif /* __ASM_HUGETLB_H */
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index b4bbeed80fb6..6914add66bcf 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -1093,6 +1093,15 @@ static inline bool pud_sect_supported(void)
}
+#define __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION
+#define ptep_modify_prot_start ptep_modify_prot_start
+extern pte_t ptep_modify_prot_start(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep);
+
+#define ptep_modify_prot_commit ptep_modify_prot_commit
+extern void ptep_modify_prot_commit(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ pte_t old_pte, pte_t new_pte);
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_PGTABLE_H */
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 89ac00084f38..307faa2b4395 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -661,6 +661,13 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
CAP_MIDR_RANGE_LIST(trbe_write_out_of_range_cpus),
},
#endif
+#ifdef CONFIG_ARM64_ERRATUM_2645198
+ {
+ .desc = "ARM erratum 2645198",
+ .capability = ARM64_WORKAROUND_2645198,
+ ERRATA_MIDR_ALL_VERSIONS(MIDR_CORTEX_A715)
+ },
+#endif
#ifdef CONFIG_ARM64_ERRATUM_2077057
{
.desc = "ARM erratum 2077057",
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 35e9a468d13e..95364e8bdc19 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -559,3 +559,24 @@ bool __init arch_hugetlb_valid_size(unsigned long size)
{
return __hugetlb_valid_size(size);
}
+
+pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
+{
+ if (IS_ENABLED(CONFIG_ARM64_ERRATUM_2645198) &&
+ cpus_have_const_cap(ARM64_WORKAROUND_2645198)) {
+ /*
+ * Break-before-make (BBM) is required for all user space mappings
+ * when the permission changes from executable to non-executable
+ * in cases where cpu is affected with errata #2645198.
+ */
+ if (pte_user_exec(READ_ONCE(*ptep)))
+ return huge_ptep_clear_flush(vma, addr, ptep);
+ }
+ return huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
+}
+
+void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep,
+ pte_t old_pte, pte_t pte)
+{
+ set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
+}
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 14c87e8d69d8..d77c9f56b7b4 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1630,3 +1630,24 @@ static int __init prevent_bootmem_remove_init(void)
}
early_initcall(prevent_bootmem_remove_init);
#endif
+
+pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
+{
+ if (IS_ENABLED(CONFIG_ARM64_ERRATUM_2645198) &&
+ cpus_have_const_cap(ARM64_WORKAROUND_2645198)) {
+ /*
+ * Break-before-make (BBM) is required for all user space mappings
+ * when the permission changes from executable to non-executable
+ * in cases where cpu is affected with errata #2645198.
+ */
+ if (pte_user_exec(READ_ONCE(*ptep)))
+ return ptep_clear_flush(vma, addr, ptep);
+ }
+ return ptep_get_and_clear(vma->vm_mm, addr, ptep);
+}
+
+void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep,
+ pte_t old_pte, pte_t pte)
+{
+ set_pte_at(vma->vm_mm, addr, ptep, pte);
+}
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index a86ee376920a..dfeb2c51e257 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -71,6 +71,7 @@ WORKAROUND_2038923
WORKAROUND_2064142
WORKAROUND_2077057
WORKAROUND_2457168
+WORKAROUND_2645198
WORKAROUND_2658417
WORKAROUND_TRBE_OVERWRITE_FILL_MODE
WORKAROUND_TSB_FLUSH_FAILURE
--
2.25.1
On Mon, 2 Jan 2023 11:46:51 +0530, Anshuman Khandual wrote:
> If a Cortex-A715 cpu sees a page mapping permissions change from executable
> to non-executable, it may corrupt the ESR_ELx and FAR_ELx registers, on the
> next instruction abort caused by permission fault.
>
> Only user-space does executable to non-executable permission transition via
> mprotect() system call which calls ptep_modify_prot_start() and ptep_modify
> _prot_commit() helpers, while changing the page mapping. The platform code
> can override these helpers via __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION.
>
> [...]
Applied to arm64 (for-next/fixes), thanks!
[1/1] arm64: errata: Workaround possible Cortex-A715 [ESR|FAR]_ELx corruption
https://git.kernel.org/arm64/c/5db568e748f6
Cheers,
--
Will
https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev