[PATCH v2] riscv: mm: add paging_check() before paging_init()
From: Yunhui Cui
Date: Thu Jul 25 2024 - 03:42:16 EST
When establishing a linear mapping, the virtual address is obtained
through __va(). If the physical address is too large, such as 1TB, then
the virtual address will overflow in the address space of sv39.
The log is as follows:
[ 0.000000] Unable to handle kernel paging request at virtual address 000000d97fdf7ad8
[ 0.000000] [000000d97fdf7ad8] pgd=000000407ff7e801, p4d=000000407ff7e801, pud=000000407ff7e801
[ 0.000000] Unable to handle kernel paging request at virtual address 000000d97fdfaff0
[ 0.000000] [000000d97fdfaff0] pgd=000000407ff7e801, p4d=000000407ff7e801, pud=000000407ff7e801
...
[ 0.000000] Insufficient stack space to handle exception!
[ 0.000000] Task stack: [0xffffffff81400000..0xffffffff81404000]
[ 0.000000] Overflow stack: [0xffffffff80c67370..0xffffffff80c68370]
[ 0.000000] CPU: 0 PID: 0 Comm: swapper Tainted: G W 6.6.3-00133-g60497fad461d-dirty #71
[ 0.000000] epc : die_kernel_fault+0x158/0x1c8
[ 0.000000] ra : die_kernel_fault+0x12a/0x1c8
[ 0.000000] epc : ffffffff808cde36 ra : ffffffff808cde08 sp : ffffffff813fff80
[ 0.000000] gp : ffffffff815a1678 tp : 0000000000000000 t0 : 0000003130386537
[ 0.000000] t1 : 0000000000000031 t2 : 6537666637303430 s0 : ffffffff813fffc0
[ 0.000000] s1 : ffffffff815b0b28 a0 : 0000000000000016 a1 : ffffffff81495298
[ 0.000000] a2 : 0000000000000010 a3 : ffffffff81495298 a4 : 00000000000001fe
[ 0.000000] a5 : 000000d97fdfa000 a6 : ffffffff814250d0 a7 : 0000000000000030
[ 0.000000] s2 : 000000d97fdfaff0 s3 : ffffffff81400040 s4 : 000000d97fdfaff0
[ 0.000000] s5 : ffffffff815a0ed0 s6 : 0000000000000000 s7 : 000000008f604390
[ 0.000000] s8 : 0000000000000000 s9 : ffffffffffffffff s10: 0000000000000000
[ 0.000000] s11: 0000000000000000 t3 : ffffffff815baa9b t4 : ffffffff815baa9b
[ 0.000000] t5 : ffffffff815baa88 t6 : ffffffff813ffda8
[ 0.000000] status: 0000000200000100 badaddr: 000000d97fdfaff0 cause: 000000000000000d
[ 0.000000] Kernel panic - not syncing: Kernel stack overflow
[ 0.000000] CPU: 0 PID: 0 Comm: swapper Tainted: G W 6.6.3-00133-g60497fad461d-dirty #71
[ 0.000000] Call Trace:
[ 0.000000] [<ffffffff800066bc>] dump_backtrace+0x28/0x30
[ 0.000000] [<ffffffff808cdac8>] show_stack+0x38/0x44
[ 0.000000] [<ffffffff808d9d40>] dump_stack_lvl+0x44/0x5c
[ 0.000000] [<ffffffff808d9d70>] dump_stack+0x18/0x20
[ 0.000000] [<ffffffff808cdfb6>] panic+0x110/0x2f2
[ 0.000000] [<ffffffff80006532>] walk_stackframe+0x0/0x120
[ 0.000000] [<ffffffff808cde08>] die_kernel_fault+0x12a/0x1c8
[ 0.000000] ---[ end Kernel panic - not syncing: Kernel stack overflow ]---
In other words, the maximum value of the physical address needs to meet
Documentation/riscv/vm-layout.rst to ensure that there is no overflow.
For sv48/57, the actual virtual address space is huge, so this problem
is generally not triggered, but it is also checked in the code.
We give a warning for the overflowed physical address region and reverve it
so that the kernel can bringup successfully.
Signed-off-by: Yunhui Cui <cuiyunhui@xxxxxxxxxxxxx>
---
arch/riscv/include/asm/page.h | 9 +++++++++
arch/riscv/include/asm/pgtable.h | 1 +
arch/riscv/kernel/setup.c | 1 +
arch/riscv/mm/init.c | 30 ++++++++++++++++++++++++++++++
4 files changed, 41 insertions(+)
diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 57e887bfa34c..f6c0f6e14ecb 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -38,6 +38,15 @@
*/
#define PAGE_OFFSET_L4 _AC(0xffffaf8000000000, UL)
#define PAGE_OFFSET_L3 _AC(0xffffffd800000000, UL)
+
+/*
+ * See vm-layout.rst, the size of L3 direct mapping of all physical
+ * memory 124GB, L4 is 64TB, L5 is 32PB.
+ */
+#define MAX_PFN_MEM_ADDR_L5 (0x80000000000000ULL)
+#define MAX_PFN_MEM_ADDR_L4 (0x400000000000ULL)
+#define MAX_PFN_MEM_ADDR_L3 (0x1F00000000ULL)
+
#else
#define PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL)
#endif /* CONFIG_64BIT */
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index c8e8867c42f6..e4835de5a743 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -915,6 +915,7 @@ extern uintptr_t _dtb_early_pa;
#endif /* CONFIG_XIP_KERNEL */
extern u64 satp_mode;
+void paging_check(void);
void paging_init(void);
void misc_mem_init(void);
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 2a79d4ed2660..366918578544 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -273,6 +273,7 @@ void __init setup_arch(char **cmdline_p)
parse_early_param();
efi_init();
+ paging_check();
paging_init();
/* Parse the ACPI tables for possible boot-time configuration */
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index b0cc28f7595f..aa25dcf8a0ff 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -1482,6 +1482,36 @@ static void __init reserve_crashkernel(void)
crashk_res.end = crash_base + crash_size - 1;
}
+static void __init phymem_addr_overflow(void)
+{
+ phys_addr_t end = memblock_end_of_DRAM();
+
+ if (pgtable_l5_enabled) {
+ if (end > MAX_PFN_MEM_ADDR_L5) {
+ memblock_reserve(MAX_PFN_MEM_ADDR_L5, end - MAX_PFN_MEM_ADDR_L5);
+ WARN(true, "Phymem addr 0x%llx overflowed, reserve [0x%llx-0x%llx] directly.",
+ end, MAX_PFN_MEM_ADDR_L5, end);
+ }
+ }
+ if (pgtable_l4_enabled) {
+ if (end > MAX_PFN_MEM_ADDR_L4) {
+ memblock_reserve(MAX_PFN_MEM_ADDR_L4, end - MAX_PFN_MEM_ADDR_L4);
+ WARN(true, "Phymem addr 0x%llx overflowed, reserve [0x%llx-0x%llx] directly.",
+ end, MAX_PFN_MEM_ADDR_L4, end);
+ }
+ }
+ if (end > MAX_PFN_MEM_ADDR_L3) {
+ memblock_reserve(MAX_PFN_MEM_ADDR_L3, end - MAX_PFN_MEM_ADDR_L3);
+ WARN(true, "Phymem addr 0x%llx overflowed, reserve [0x%llx-0x%llx] directly.",
+ end, MAX_PFN_MEM_ADDR_L3, end);
+ }
+}
+
+void __init paging_check(void)
+{
+ phymem_addr_overflow();
+}
+
void __init paging_init(void)
{
setup_bootmem();
--
2.39.2