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arm64/mm: Re-organise setting up FEAT_S1PIE registers PIRE0_EL1 and PIR_EL1

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mov_q cannot really move PIE_E[0|1] macros into a general purpose register
as expected if those macro constants contain some 128 bit layout elements,
that are required for D128 page tables. The primary issue is that for D128,
PIE_E[0|1] are defined in terms of 128-bit types with shifting and masking,
which the assembler can't accommodate.

Instead pre-calculate these PIRE0_EL1/PIR_EL1 constants into asm-offsets.h
based PIE_E0_ASM/PIE_E1_ASM which can then be used in arch/arm64/mm/proc.S.

While here also drop PTE_MAYBE_NG/PTE_MAYBE_SHARED assembly overrides which
are not required any longer, as the compiler toolchains are smart enough to
compute both the PIE_[E0|E1]_ASM constants in all scenarios.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Link: https://lore.kernel.org/r/20250429050511.1663235-1-anshuman.khandual@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Anshuman Khandual 2025-04-29 10:35:11 +05:30 committed by Will Deacon
parent c8597e2dd8
commit 29e31da4ed
2 changed files with 4 additions and 17 deletions
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2
arch/arm64/kernel/asm-offsets.c
View File

@ -182,5 +182,7 @@ int main(void)
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
DEFINE(FTRACE_OPS_DIRECT_CALL, offsetof(struct ftrace_ops, direct_call));
#endif
DEFINE(PIE_E0_ASM, PIE_E0);
DEFINE(PIE_E1_ASM, PIE_E1);
return 0;
}

19
arch/arm64/mm/proc.S
View File

@ -512,26 +512,11 @@ 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
#define PTE_MAYBE_SHARED 0
mov_q x0, PIE_E0
mov_q x0, PIE_E0_ASM
msr REG_PIRE0_EL1, x0
mov_q x0, PIE_E1
mov_q x0, PIE_E1_ASM
msr REG_PIR_EL1, x0
#undef PTE_MAYBE_NG
#undef PTE_MAYBE_SHARED
orr tcr2, tcr2, TCR2_EL1_PIE
msr REG_TCR2_EL1, x0