6.12-stable review patch. If anyone has any objections, please let me know.
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From: Björn Töpel bjorn@rivosinc.com
[ Upstream commit e94eb7ea6f206e229791761a5fdf9389f8dbd183 ]
The /proc/iomem represents the kernel's memory map. Regions marked with "Reserved" tells the user that the range should not be tampered with. Kexec-tools, when using the older kexec_load syscall relies on the "Reserved" regions to build the memory segments, that will be the target of the new kexec'd kernel.
The RISC-V port tries to expose all reserved regions to userland, but some regions were not properly exposed: Regions that resided in both the "regular" and reserved memory block, e.g. the EFI Memory Map. A missing entry could result in reserved memory being overwritten.
It turns out, that arm64, and loongarch had a similar issue a while back:
commit d91680e687f4 ("arm64: Fix /proc/iomem for reserved but not memory regions") commit 50d7ba36b916 ("arm64: export memblock_reserve()d regions via /proc/iomem")
Similar to the other ports, resolve the issue by splitting the regions in an arch initcall, since we need a working allocator.
Fixes: ffe0e5261268 ("RISC-V: Improve init_resources()") Signed-off-by: Björn Töpel bjorn@rivosinc.com Reviewed-by: Alexandre Ghiti alexghiti@rivosinc.com Link: https://lore.kernel.org/r/20250409182129.634415-1-bjorn@kernel.org Signed-off-by: Alexandre Ghiti alexghiti@rivosinc.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/riscv/kernel/setup.c | 36 +++++++++++++++++++++++++++++++++++- 1 file changed, 35 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c index 7934613a98c88..194bda6d74ce7 100644 --- a/arch/riscv/kernel/setup.c +++ b/arch/riscv/kernel/setup.c @@ -66,6 +66,9 @@ static struct resource bss_res = { .name = "Kernel bss", }; static struct resource elfcorehdr_res = { .name = "ELF Core hdr", }; #endif
+static int num_standard_resources; +static struct resource *standard_resources; + static int __init add_resource(struct resource *parent, struct resource *res) { @@ -139,7 +142,7 @@ static void __init init_resources(void) struct resource *res = NULL; struct resource *mem_res = NULL; size_t mem_res_sz = 0; - int num_resources = 0, res_idx = 0; + int num_resources = 0, res_idx = 0, non_resv_res = 0; int ret = 0;
/* + 1 as memblock_alloc() might increase memblock.reserved.cnt */ @@ -195,6 +198,7 @@ static void __init init_resources(void) /* Add /memory regions to the resource tree */ for_each_mem_region(region) { res = &mem_res[res_idx--]; + non_resv_res++;
if (unlikely(memblock_is_nomap(region))) { res->name = "Reserved"; @@ -212,6 +216,9 @@ static void __init init_resources(void) goto error; }
+ num_standard_resources = non_resv_res; + standard_resources = &mem_res[res_idx + 1]; + /* Clean-up any unused pre-allocated resources */ if (res_idx >= 0) memblock_free(mem_res, (res_idx + 1) * sizeof(*mem_res)); @@ -223,6 +230,33 @@ static void __init init_resources(void) memblock_free(mem_res, mem_res_sz); }
+static int __init reserve_memblock_reserved_regions(void) +{ + u64 i, j; + + for (i = 0; i < num_standard_resources; i++) { + struct resource *mem = &standard_resources[i]; + phys_addr_t r_start, r_end, mem_size = resource_size(mem); + + if (!memblock_is_region_reserved(mem->start, mem_size)) + continue; + + for_each_reserved_mem_range(j, &r_start, &r_end) { + resource_size_t start, end; + + start = max(PFN_PHYS(PFN_DOWN(r_start)), mem->start); + end = min(PFN_PHYS(PFN_UP(r_end)) - 1, mem->end); + + if (start > mem->end || end < mem->start) + continue; + + reserve_region_with_split(mem, start, end, "Reserved"); + } + } + + return 0; +} +arch_initcall(reserve_memblock_reserved_regions);
static void __init parse_dtb(void) {