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'arch_calc_vm_prot_bits' is implemented on risc-v to return VM_READ | VM_WRITE if PROT_WRITE is specified. Similarly 'riscv_sys_mmap' is updated to convert all incoming PROT_WRITE to (PROT_WRITE | PROT_READ). This is to make sure that any existing apps using PROT_WRITE still work. Earlier 'protection_map[VM_WRITE]' used to pick read-write PTE encodings. Now 'protection_map[VM_WRITE]' will always pick PAGE_SHADOWSTACK PTE encodings for shadow stack. The above changes ensure that existing apps continue to work because underneath, the kernel will be picking 'protection_map[VM_WRITE|VM_READ]' PTE encodings. Reviewed-by: Zong Li <zong.li@sifive.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Signed-off-by: Deepak Gupta <debug@rivosinc.com> Tested-by: Andreas Korb <andreas.korb@aisec.fraunhofer.de> # QEMU, custom CVA6 Tested-by: Valentin Haudiquet <valentin.haudiquet@canonical.com> Link: https://patch.msgid.link/20251112-v5_user_cfi_series-v23-6-b55691eacf4f@rivosinc.com Signed-off-by: Paul Walmsley <pjw@kernel.org>
27 lines
623 B
C
27 lines
623 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_MMAN_H__
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#define __ASM_MMAN_H__
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#include <linux/compiler.h>
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <uapi/asm/mman.h>
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static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
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unsigned long pkey __always_unused)
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{
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unsigned long ret = 0;
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/*
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* If PROT_WRITE was specified, force it to VM_READ | VM_WRITE.
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* Only VM_WRITE means shadow stack.
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*/
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if (prot & PROT_WRITE)
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ret = (VM_READ | VM_WRITE);
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return ret;
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}
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#define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey)
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#endif /* ! __ASM_MMAN_H__ */
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