diff options
| author | Ard Biesheuvel <ardb@kernel.org> | 2024-02-14 13:29:13 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2024-02-16 12:42:37 +0000 |
| commit | 60d043c101769b4fd6f609b4a7b9b8ad1f867860 (patch) | |
| tree | bb01b6807a89167398520cbd578ffdabb253704c | |
| parent | 68aec33f8f5a87b0450159e5e141d2d6c9d76850 (diff) | |
arm64: Avoid #define'ing PTE_MAYBE_NG to 0x0 for asm use
The PROT_* macros resolve to expressions that are only valid in C and
not in assembler, and so they are only usable from C code. Currently, we
make an exception for the permission indirection init code in proc.S,
which doesn't care about the bits that are conditionally set, and so we
just #define PTE_MAYBE_NG to 0x0 for any assembler file that includes
these definitions.
This is dodgy because this means that PROT_NORMAL and friends is
generally available in asm code, but defined in a way that deviates from
the definition that C code will observe, which might lead to hard to
diagnose issues down the road.
So instead, #define PTE_MAYBE_NG only in the place where the PIE
constants are evaluated, and #undef it again right after. This allows us
to drop the #define from pgtable-prot.h, and avoid the risk of deviating
definitions between asm and C.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-72-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
| -rw-r--r-- | arch/arm64/include/asm/pgtable-prot.h | 4 | ||||
| -rw-r--r-- | arch/arm64/mm/proc.S | 13 |
2 files changed, 13 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h index 483dbfa39c4c..63ced9ccec21 100644 --- a/arch/arm64/include/asm/pgtable-prot.h +++ b/arch/arm64/include/asm/pgtable-prot.h @@ -57,10 +57,6 @@ #define _PAGE_READONLY_EXEC (_PAGE_DEFAULT | PTE_USER | PTE_RDONLY | PTE_NG | PTE_PXN) #define _PAGE_EXECONLY (_PAGE_DEFAULT | PTE_RDONLY | PTE_NG | PTE_PXN) -#ifdef __ASSEMBLY__ -#define PTE_MAYBE_NG 0 -#endif - #ifndef __ASSEMBLY__ #include <asm/cpufeature.h> diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index d104ddab26a4..6e1b2bc41a9f 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -456,11 +456,24 @@ alternative_else_nop_endif ubfx x1, x1, #ID_AA64MMFR3_EL1_S1PIE_SHIFT, #4 cbz x1, .Lskip_indirection + /* + * The PROT_* macros describing the various memory types may resolve to + * C expressions if they include the PTE_MAYBE_* macros, and so they + * can only be used from C code. The PIE_E* constants below are also + * defined in terms of those macros, but will mask out those + * PTE_MAYBE_* constants, whether they are set or not. So #define them + * as 0x0 here so we can evaluate the PIE_E* constants in asm context. + */ + +#define PTE_MAYBE_NG 0 + mov_q x0, PIE_E0 msr REG_PIRE0_EL1, x0 mov_q x0, PIE_E1 msr REG_PIR_EL1, x0 +#undef PTE_MAYBE_NG + mov x0, TCR2_EL1x_PIE msr REG_TCR2_EL1, x0 |