From b67a1ee0db0094c6cc158b087be6c334ad881a41 Mon Sep 17 00:00:00 2001 From: Han Gao Date: Sat, 6 Jun 2026 20:17:58 -0600 Subject: [PATCH] riscv: kexec_file: Constrain segment placement to direct map When kexec_file_load places segments with buf_max=ULONG_MAX and top_down=true, they land at the highest available physical addresses. On RISC-V the size of the linear mapping is determined by the active VM mode: SV39 caps the direct map at roughly 128GB, while SV48/SV57 extend the range substantially further. When the installed physical memory exceeds the direct map size of the active mode, top-down placement puts DTB/initrd at physical addresses outside the linearly mapped region. The kexec'd kernel cannot reach them during early boot, triggering a page fault at memcmp in start_kernel. Fix by constraining buf_max to PFN_PHYS(max_low_pfn), which reflects the runtime direct map boundary for the active VM mode (SV39/SV48/ SV57). This keeps all kexec segments within the linearly mapped region while preserving the upstream top_down allocation strategy. Signed-off-by: Han Gao Link: https://patch.msgid.link/20260519170641.123517-1-gaohan@iscas.ac.cn Signed-off-by: Paul Walmsley --- arch/riscv/kernel/machine_kexec_file.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c index 54e2d9552e93..59d4bbc848a8 100644 --- a/arch/riscv/kernel/machine_kexec_file.c +++ b/arch/riscv/kernel/machine_kexec_file.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -266,7 +267,7 @@ int load_extra_segments(struct kimage *image, unsigned long kernel_start, kbuf.image = image; kbuf.buf_min = kernel_start + kernel_len; - kbuf.buf_max = ULONG_MAX; + kbuf.buf_max = PFN_PHYS(max_low_pfn); #ifdef CONFIG_CRASH_DUMP /* Add elfcorehdr */