From f91a3a6088ea4396299f1a72f6b0302bbe21a314 Mon Sep 17 00:00:00 2001 From: Kevin Brodsky Date: Wed, 19 Feb 2025 16:40:27 +0000 Subject: [PATCH] arm64/sysreg: Improve PIR/POR helpers We currently have one helper to set a PIRx_ELx's permission field to a given value, PIRx_ELx_PERM(), and another helper to extract a permission field from POR_ELx, POR_ELx_IDX(). The naming is pretty confusing - it isn't clear at all that "_PERM" corresponds to a setter and "_IDX" to a getter. This patch aims at improving the situation by using the same suffixes as FIELD_PREP()/FIELD_GET(), which we have already adopted for SYS_FIELD_{PREP,GET}(): * PIRx_ELx_PERM_PREP(), POR_ELx_PERM_PREP() create a register value where the permission field for a given index is set to a given value. * POR_ELx_PERM_GET() extracts the permission field from a given register value for a given index. These helpers are not implemented using FIELD_PREP()/FIELD_GET() because the mask may not be constant, and they need to be usable in assembly. They are all defined in asm/sysreg.h, as one would expect for basic sysreg-related helpers. Finally the new POR_ELx_PERM_* macros are used for existing calculations in signal.c and mmu.c. Signed-off-by: Kevin Brodsky Link: https://lore.kernel.org/r/20250219164029.2309119-2-kevin.brodsky@arm.com Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/pgtable-prot.h | 36 +++++++++++++-------------- arch/arm64/include/asm/por.h | 9 +++---- arch/arm64/include/asm/sysreg.h | 10 +++++++- arch/arm64/kernel/signal.c | 2 +- arch/arm64/mm/mmu.c | 6 ++--- 5 files changed, 34 insertions(+), 29 deletions(-) diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h index a95f1f77bb39a..7830d031742e5 100644 --- a/arch/arm64/include/asm/pgtable-prot.h +++ b/arch/arm64/include/asm/pgtable-prot.h @@ -169,25 +169,25 @@ static inline bool __pure lpa2_is_enabled(void) #define PAGE_GCS_RO __pgprot(_PAGE_GCS_RO) #define PIE_E0 ( \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_GCS), PIE_GCS) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_GCS_RO), PIE_R) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_EXECONLY), PIE_X_O) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_READONLY_EXEC), PIE_RX_O) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_SHARED_EXEC), PIE_RWX_O) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_READONLY), PIE_R_O) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_SHARED), PIE_RW_O)) + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_GCS), PIE_GCS) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_GCS_RO), PIE_R) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_EXECONLY), PIE_X_O) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_READONLY_EXEC), PIE_RX_O) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_SHARED_EXEC), PIE_RWX_O) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_READONLY), PIE_R_O) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_SHARED), PIE_RW_O)) #define PIE_E1 ( \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_GCS), PIE_NONE_O) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_GCS_RO), PIE_NONE_O) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_EXECONLY), PIE_NONE_O) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_READONLY_EXEC), PIE_R) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_SHARED_EXEC), PIE_RW) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_READONLY), PIE_R) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_SHARED), PIE_RW) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_KERNEL_ROX), PIE_RX) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_KERNEL_EXEC), PIE_RWX) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_KERNEL_RO), PIE_R) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_KERNEL), PIE_RW)) + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_GCS), PIE_NONE_O) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_GCS_RO), PIE_NONE_O) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_EXECONLY), PIE_NONE_O) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_READONLY_EXEC), PIE_R) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_SHARED_EXEC), PIE_RW) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_READONLY), PIE_R) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_SHARED), PIE_RW) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_KERNEL_ROX), PIE_RX) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_KERNEL_EXEC), PIE_RWX) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_KERNEL_RO), PIE_R) | \ + PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_KERNEL), PIE_RW)) #endif /* __ASM_PGTABLE_PROT_H */ diff --git a/arch/arm64/include/asm/por.h b/arch/arm64/include/asm/por.h index e06e9f473675f..e6bf00bd05003 100644 --- a/arch/arm64/include/asm/por.h +++ b/arch/arm64/include/asm/por.h @@ -6,26 +6,25 @@ #ifndef _ASM_ARM64_POR_H #define _ASM_ARM64_POR_H -#define POR_BITS_PER_PKEY 4 -#define POR_ELx_IDX(por_elx, idx) (((por_elx) >> ((idx) * POR_BITS_PER_PKEY)) & 0xf) +#include static inline bool por_elx_allows_read(u64 por, u8 pkey) { - u8 perm = POR_ELx_IDX(por, pkey); + u8 perm = POR_ELx_PERM_GET(pkey, por); return perm & POE_R; } static inline bool por_elx_allows_write(u64 por, u8 pkey) { - u8 perm = POR_ELx_IDX(por, pkey); + u8 perm = POR_ELx_PERM_GET(pkey, por); return perm & POE_W; } static inline bool por_elx_allows_exec(u64 por, u8 pkey) { - u8 perm = POR_ELx_IDX(por, pkey); + u8 perm = POR_ELx_PERM_GET(pkey, por); return perm & POE_X; } diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index 05ea5223d2d55..c9ce4ce5131c8 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -1062,8 +1062,11 @@ #define PIE_RX UL(0xa) #define PIE_RW UL(0xc) #define PIE_RWX UL(0xe) +#define PIE_MASK UL(0xf) -#define PIRx_ELx_PERM(idx, perm) ((perm) << ((idx) * 4)) +#define PIRx_ELx_BITS_PER_IDX 4 +#define PIRx_ELx_PERM_SHIFT(idx) ((idx) * PIRx_ELx_BITS_PER_IDX) +#define PIRx_ELx_PERM_PREP(idx, perm) (((perm) & PIE_MASK) << PIRx_ELx_PERM_SHIFT(idx)) /* * Permission Overlay Extension (POE) permission encodings. @@ -1078,6 +1081,11 @@ #define POE_RXW UL(0x7) #define POE_MASK UL(0xf) +#define POR_ELx_BITS_PER_IDX 4 +#define POR_ELx_PERM_SHIFT(idx) ((idx) * POR_ELx_BITS_PER_IDX) +#define POR_ELx_PERM_GET(idx, reg) (((reg) >> POR_ELx_PERM_SHIFT(idx)) & POE_MASK) +#define POR_ELx_PERM_PREP(idx, perm) (((perm) & POE_MASK) << POR_ELx_PERM_SHIFT(idx)) + /* Initial value for Permission Overlay Extension for EL0 */ #define POR_EL0_INIT POE_RXW diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index 99ea26d400ffe..bf62262565499 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -91,7 +91,7 @@ static void save_reset_user_access_state(struct user_access_state *ua_state) u64 por_enable_all = 0; for (int pkey = 0; pkey < arch_max_pkey(); pkey++) - por_enable_all |= POE_RXW << (pkey * POR_BITS_PER_PKEY); + por_enable_all |= POR_ELx_PERM_PREP(pkey, POE_RXW); ua_state->por_el0 = read_sysreg_s(SYS_POR_EL0); write_sysreg_s(por_enable_all, SYS_POR_EL0); diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index b4df5bc5b1b8b..69a83a77ccce1 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1557,7 +1557,6 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, unsigned long i { u64 new_por = POE_RXW; u64 old_por; - u64 pkey_shift; if (!system_supports_poe()) return -ENOSPC; @@ -1582,12 +1581,11 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, unsigned long i new_por &= ~POE_X; /* Shift the bits in to the correct place in POR for pkey: */ - pkey_shift = pkey * POR_BITS_PER_PKEY; - new_por <<= pkey_shift; + new_por = POR_ELx_PERM_PREP(pkey, new_por); /* Get old POR and mask off any old bits in place: */ old_por = read_sysreg_s(SYS_POR_EL0); - old_por &= ~(POE_MASK << pkey_shift); + old_por &= ~(POE_MASK << POR_ELx_PERM_SHIFT(pkey)); /* Write old part along with new part: */ write_sysreg_s(old_por | new_por, SYS_POR_EL0);