Re: [PATCH] riscv: Get rid of MAX_EARLY_MAPPING_SIZE

From: Alex Ghiti
Date: Mon Feb 22 2021 - 00:41:13 EST

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Hi Dmitry,

Le 2/21/21 à 10:38 AM, Dmitry Vyukov a écrit :

On Sun, Feb 21, 2021 at 3:22 PM Alexandre Ghiti <alex@xxxxxxxx> wrote:

At early boot stage, we have a whole PGDIR to map the kernel, so there
is no need to restrict the early mapping size to 128MB. Removing this
define also allows us to simplify some compile time logic.

This fixes large kernel mappings with a size greater than 128MB, as it
is the case for syzbot kernels whose size was just ~130MB.

Note that on rv64, for now, we are then limited to PGDIR size for early
mapping as we can't use PGD mappings (see [1]). That should be enough
given the relative small size of syzbot kernels compared to PGDIR_SIZE
which is 1GB.

[1] https://lore.kernel.org/lkml/20200603153608.30056-1-alex@xxxxxxxx/

I've applied this patch to (as it contains the HEAD fix):

commit f49815047c1a3e3644a0ba38f3825c5cde8a0922 (HEAD, riscv/for-next)
Author: Tobias Klauser <tklauser@xxxxxxxxxx>
Date: Tue Feb 16 18:33:05 2021 +0100
riscv: Disable KSAN_SANITIZE for vDSO

and the kernel started booting with my large config.
It quickly crashed (see below), but at least it started booting, so
it's an improvement.

Tested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>

Thanks for that.

Linux version 5.11.0-rc2-00069-gf49815047c1a-dirty
(dvyukov@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx) (riscv64-linux-gnu-gcc
(Debian 10.2.1-6+build1) 10.2.1 20210110, GNU ld (GNU Binutils for
Debian) 2.35.1) #34 SMP PREEMPT Sun Feb 21 15:51:40 CET 2021
OF: fdt: Ignoring memory range 0x80000000 - 0x80200000
Machine model: riscv-virtio,qemu
earlycon: ns16550a0 at MMIO 0x0000000010000000 (options '')
printk: bootconsole [ns16550a0] enabled
efi: UEFI not found.
cma: Reserved 16 MiB at 0x00000000fec00000
Zone ranges:
DMA32 [mem 0x0000000080200000-0x00000000ffffffff]
Normal empty
Movable zone start for each node
Early memory node ranges
node 0: [mem 0x0000000080200000-0x00000000ffffffff]
Zeroed struct page in unavailable ranges: 512 pages
Initmem setup node 0 [mem 0x0000000080200000-0x00000000ffffffff]
SBI specification v0.2 detected
SBI implementation ID=0x1 Version=0x8
SBI v0.2 TIME extension detected
SBI v0.2 IPI extension detected
SBI v0.2 RFENCE extension detected
software IO TLB: mapped [mem 0x00000000f7c00000-0x00000000fbc00000] (64MB)
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled)
WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:4085
lockdep_hardirqs_on_prepare+0x384/0x388 kernel/locking/lockdep.c:4085
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 5.11.0-rc2-00069-gf49815047c1a-dirty #34
Hardware name: riscv-virtio,qemu (DT)
epc : lockdep_hardirqs_on_prepare+0x384/0x388 kernel/locking/lockdep.c:4085
ra : lockdep_hardirqs_on_prepare+0x384/0x388 kernel/locking/lockdep.c:4085
epc : ffffffe0000c125a ra : ffffffe0000c125a sp : ffffffe006603ce0
gp : ffffffe006c338f0 tp : ffffffe006689e00 t0 : ffffffe00669a9a8
t1 : ffffffc400cc0738 t2 : 0000000000000000 s0 : ffffffe006603d20
s1 : ffffffe006689e00 a0 : 000000000000002d a1 : 00000000000f0000
a2 : 0000000000000002 a3 : ffffffe0000d2718 a4 : 0000000000000000
a5 : 0000000000000000 a6 : 0000000000f00000 a7 : ffffffe0066039c7
s2 : ffffffe004a337c0 s3 : ffffffe0076fa1b8 s4 : 0000000000000000
s5 : ffffffe006689e00 s6 : 0000000000000001 s7 : ffffffe07fcfc000
s8 : ffffffe07fcfd000 s9 : ffffffe006c3c0d0 s10: fffffffffffff000
s11: ffffffe004a1fbb8 t3 : 000000002d2d2d2d t4 : ffffffc400cc0737
t5 : ffffffc400cc0739 t6 : ffffffe0066039c8
status: 0000000000000100 badaddr: 0000000000000000 cause: 0000000000000003
Call Trace:
[<ffffffe0000c125a>] lockdep_hardirqs_on_prepare+0x384/0x388
kernel/locking/lockdep.c:4085
[<ffffffe0001b7dc0>] trace_hardirqs_on+0x116/0x174
kernel/trace/trace_preemptirq.c:49
[<ffffffe00000550a>] _save_context+0xa2/0xe2
[<ffffffe004807908>] local_flush_tlb_all
arch/riscv/include/asm/tlbflush.h:16 [inline]
[<ffffffe004807908>] populate arch/riscv/mm/kasan_init.c:95 [inline]
[<ffffffe004807908>] kasan_init+0x23e/0x31a arch/riscv/mm/kasan_init.c:157
irq event stamp: 0
hardirqs last enabled at (0): [<0000000000000000>] 0x0
hardirqs last disabled at (0): [<0000000000000000>] 0x0
softirqs last enabled at (0): [<0000000000000000>] 0x0
softirqs last disabled at (0): [<0000000000000000>] 0x0
random: get_random_bytes called from init_oops_id kernel/panic.c:546
[inline] with crng_init=0
random: get_random_bytes called from init_oops_id kernel/panic.c:543
[inline] with crng_init=0
random: get_random_bytes called from print_oops_end_marker
kernel/panic.c:556 [inline] with crng_init=0
random: get_random_bytes called from __warn+0x1be/0x20a
kernel/panic.c:613 with crng_init=0
---[ end trace 0000000000000000 ]---
Unable to handle kernel paging request at virtual address dfffffc810040000
Oops [#1]
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Tainted: G W
5.11.0-rc2-00069-gf49815047c1a-dirty #34
Hardware name: riscv-virtio,qemu (DT)
epc : __memset+0x60/0xfc arch/riscv/lib/memset.S:67
ra : populate arch/riscv/mm/kasan_init.c:96 [inline]
ra : kasan_init+0x256/0x31a arch/riscv/mm/kasan_init.c:157
epc : ffffffe001791cf0 ra : ffffffe004807920 sp : ffffffe006603e80
gp : ffffffe006c338f0 tp : ffffffe006689e00 t0 : dfffffc810040000
t1 : ffffffe004a1fc80 t2 : 0000000000000000 s0 : ffffffe006603f30
s1 : 0000000000000001 a0 : dfffffc810040000 a1 : 0000000000000000
a2 : 000000000ffc0000 a3 : dfffffc820000000 a4 : 0000000000000000
a5 : dfffffc820000000 a6 : 0000000000f00000 a7 : ffffffe004a1fcaf
s2 : dfffffc810040000 s3 : 000000000000ffc0 s4 : dfffffc800000000
s5 : ffffffe006c46908 s6 : 0000000000000001 s7 : ffffffe07fcfc000
s8 : ffffffe07fcfd000 s9 : ffffffe006c3c0d0 s10: fffffffffffff000
s11: ffffffe004a1fbb8 t3 : 0000000000000000 t4 : 0000000000000001
t5 : ffffffc400943f96 t6 : ffffffe006603b98
status: 0000000000000100 badaddr: dfffffc810040000 cause: 000000000000000f
Call Trace:
[<ffffffe001791cf0>] __memset+0x60/0xfc arch/riscv/lib/memset.S:65
[<ffffffe004805e7a>] setup_arch+0x6c4/0x6f2 arch/riscv/kernel/setup.c:271
[<ffffffe0048010ea>] start_kernel+0xca/0x5d6 init/main.c:871
---[ end trace f68728a0d3053b52 ]---

Ok this issue lies in for-next as I had no problem getting to init on both master and my sv48 patchset, I'm taking a look at that !

Thanks,

Alex

Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx>
---
arch/riscv/mm/init.c | 21 +++++----------------
1 file changed, 5 insertions(+), 16 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index f9f9568d689e..f81f813b9603 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -226,8 +226,6 @@ pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
pgd_t trampoline_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
pte_t fixmap_pte[PTRS_PER_PTE] __page_aligned_bss;

-#define MAX_EARLY_MAPPING_SIZE SZ_128M
-
pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);

void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot)
@@ -302,13 +300,7 @@ static void __init create_pte_mapping(pte_t *ptep,

pmd_t trampoline_pmd[PTRS_PER_PMD] __page_aligned_bss;
pmd_t fixmap_pmd[PTRS_PER_PMD] __page_aligned_bss;
-
-#if MAX_EARLY_MAPPING_SIZE < PGDIR_SIZE
-#define NUM_EARLY_PMDS 1UL
-#else
-#define NUM_EARLY_PMDS (1UL + MAX_EARLY_MAPPING_SIZE / PGDIR_SIZE)
-#endif
-pmd_t early_pmd[PTRS_PER_PMD * NUM_EARLY_PMDS] __initdata __aligned(PAGE_SIZE);
+pmd_t early_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
pmd_t early_dtb_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);

static pmd_t *__init get_pmd_virt_early(phys_addr_t pa)
@@ -330,11 +322,9 @@ static pmd_t *get_pmd_virt_late(phys_addr_t pa)

static phys_addr_t __init alloc_pmd_early(uintptr_t va)
{
- uintptr_t pmd_num;
+ BUG_ON((va - PAGE_OFFSET) >> PGDIR_SHIFT);

- pmd_num = (va - PAGE_OFFSET) >> PGDIR_SHIFT;
- BUG_ON(pmd_num >= NUM_EARLY_PMDS);
- return (uintptr_t)&early_pmd[pmd_num * PTRS_PER_PMD];
+ return (uintptr_t)early_pmd;
}

static phys_addr_t __init alloc_pmd_fixmap(uintptr_t va)
@@ -452,7 +442,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
uintptr_t va, pa, end_va;
uintptr_t load_pa = (uintptr_t)(&_start);
uintptr_t load_sz = (uintptr_t)(&_end) - load_pa;
- uintptr_t map_size = best_map_size(load_pa, MAX_EARLY_MAPPING_SIZE);
+ uintptr_t map_size;
#ifndef __PAGETABLE_PMD_FOLDED
pmd_t fix_bmap_spmd, fix_bmap_epmd;
#endif
@@ -464,12 +454,11 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
* Enforce boot alignment requirements of RV32 and
* RV64 by only allowing PMD or PGD mappings.
*/
- BUG_ON(map_size == PAGE_SIZE);
+ map_size = PMD_SIZE;

/* Sanity check alignment and size */
BUG_ON((PAGE_OFFSET % PGDIR_SIZE) != 0);
BUG_ON((load_pa % map_size) != 0);
- BUG_ON(load_sz > MAX_EARLY_MAPPING_SIZE);

pt_ops.alloc_pte = alloc_pte_early;
pt_ops.get_pte_virt = get_pte_virt_early;
--
2.20.1

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Next message: Dan Carpenter: "Re: [PATCH] staging: wimax: fix sparse incorrect type issue"
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In reply to: Dmitry Vyukov: "Re: [PATCH] riscv: Get rid of MAX_EARLY_MAPPING_SIZE"
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