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authorClément Léger <cleger@rivosinc.com>2024-04-10 16:45:57 +0200
committerPalmer Dabbelt <palmer@rivosinc.com>2024-07-11 08:57:33 -0700
commitc9b8cd139c1dfb95eb86fd6a58cfe2089843d1d4 (patch)
tree60e0509f755dfbb1ebc22e52ec6b0a58fc756919 /arch/riscv/include/asm/processor.h
parent16badacd8af48980c546839626d0329bab32b4c3 (diff)
riscv: hwprobe: export highest virtual userspace address
Some userspace applications (OpenJDK for instance) uses the free MSBs in pointers to insert additional information for their own logic and need to get this information from somewhere. Currently they rely on parsing /proc/cpuinfo "mmu=svxx" string to obtain the current value of virtual address usable bits [1]. Since this reflect the raw supported MMU mode, it might differ from the logical one used internally which is why arch_get_mmap_end() is used. Exporting the highest mmapable address through hwprobe will allow a more stable interface to be used. For that purpose, add a new hwprobe key named RISCV_HWPROBE_KEY_HIGHEST_VIRT_ADDRESS which will export the highest userspace virtual address. Link: https://github.com/openjdk/jdk/blob/master/src/hotspot/os_cpu/linux_riscv/vm_version_linux_riscv.cpp#L171 [1] Signed-off-by: Clément Léger <cleger@rivosinc.com> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Link: https://lore.kernel.org/r/20240410144558.1104006-1-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'arch/riscv/include/asm/processor.h')
-rw-r--r--arch/riscv/include/asm/processor.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index 68c3432dc6ea..8702b8721a27 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -57,6 +57,12 @@
#define STACK_TOP DEFAULT_MAP_WINDOW
+#ifdef CONFIG_MMU
+#define user_max_virt_addr() arch_get_mmap_end(ULONG_MAX, 0, 0)
+#else
+#define user_max_virt_addr() 0
+#endif /* CONFIG_MMU */
+
/*
* This decides where the kernel will search for a free chunk of vm
* space during mmap's.