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Date: Thu, 01 Apr 2021 21:33:55 -0700 (PDT)
From: Palmer Dabbelt <palmer@...belt.com>
To: Stephen Rothwell <sfr@...b.auug.org.au>
CC: Paul Walmsley <paul@...an.com>, alex@...ti.fr,
linux-kernel@...r.kernel.org, linux-next@...r.kernel.org
Subject: Re: linux-next: manual merge of the risc-v tree with Linus' tree
On Tue, 30 Mar 2021 15:40:34 PDT (-0700), Stephen Rothwell wrote:
> Hi all,
>
> Today's linux-next merge of the risc-v tree got a conflict in:
>
> arch/riscv/mm/kasan_init.c
>
> between commits:
>
> f3773dd031de ("riscv: Ensure page table writes are flushed when initializing KASAN vmalloc")
> 78947bdfd752 ("RISC-V: kasan: Declare kasan_shallow_populate() static")
>
> from Linus' tree and commit:
>
> 2da073c19641 ("riscv: Cleanup KASAN_VMALLOC support")
>
> from the risc-v tree.
>
> I fixed it up (I think - see below) and can carry the fix as
> necessary. This is now fixed as far as linux-next is concerned, but any
> non trivial conflicts should be mentioned to your upstream maintainer
> when your tree is submitted for merging. You may also want to consider
> cooperating with the maintainer of the conflicting tree to minimise any
> particularly complex conflicts.
They're my own trees ;)
I'm not so great at reading merge diffs, but the right fix here is to
have the local_flush_tlb_all() after the call to
kasan_shallow_populate_pgd(), just as there is one after
kasan_populate_pgd(). My merge diff looks like this
diff --cc arch/riscv/mm/kasan_init.c
index 2c39f0386673,4f85c6d0ddf8..ec0029097251
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@@ -162,8 -159,36 +162,10 @@@ static void __init kasan_shallow_popula
{
unsigned long vaddr = (unsigned long)start & PAGE_MASK;
unsigned long vend = PAGE_ALIGN((unsigned long)end);
- unsigned long pfn;
- int index;
- void *p;
- pud_t *pud_dir, *pud_k;
- pgd_t *pgd_dir, *pgd_k;
- p4d_t *p4d_dir, *p4d_k;
-
- while (vaddr < vend) {
- index = pgd_index(vaddr);
- pfn = csr_read(CSR_SATP) & SATP_PPN;
- pgd_dir = (pgd_t *)pfn_to_virt(pfn) + index;
- pgd_k = init_mm.pgd + index;
- pgd_dir = pgd_offset_k(vaddr);
- set_pgd(pgd_dir, *pgd_k);
-
- p4d_dir = p4d_offset(pgd_dir, vaddr);
- p4d_k = p4d_offset(pgd_k, vaddr);
-
- vaddr = (vaddr + PUD_SIZE) & PUD_MASK;
- pud_dir = pud_offset(p4d_dir, vaddr);
- pud_k = pud_offset(p4d_k, vaddr);
-
- if (pud_present(*pud_dir)) {
- p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
- pud_populate(&init_mm, pud_dir, p);
- }
- vaddr += PAGE_SIZE;
- }
+
+ kasan_shallow_populate_pgd(vaddr, vend);
+
+ local_flush_tlb_all();
}
void __init kasan_init(void)
which doesn't include the diff to kasan_shallow_populate_pgd(). Not
sure if that's just because my diff is in the other direction, though.
The expected result is that kasan_shallow_populate_pgd() exists both pre
and post merge.
>
> --
> Cheers,
> Stephen Rothwell
>
> diff --cc arch/riscv/mm/kasan_init.c
> index 4f85c6d0ddf8,2c39f0386673..000000000000
> --- a/arch/riscv/mm/kasan_init.c
> +++ b/arch/riscv/mm/kasan_init.c
> @@@ -153,44 -141,31 +141,33 @@@ static void __init kasan_populate(void
>
> local_flush_tlb_all();
> memset(start, KASAN_SHADOW_INIT, end - start);
> }
>
> + static void __init kasan_shallow_populate_pgd(unsigned long vaddr, unsigned long end)
> + {
> + unsigned long next;
> + void *p;
> + pgd_t *pgd_k = pgd_offset_k(vaddr);
> +
> + do {
> + next = pgd_addr_end(vaddr, end);
> + if (pgd_page_vaddr(*pgd_k) == (unsigned long)lm_alias(kasan_early_shadow_pmd)) {
> + p = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
> + set_pgd(pgd_k, pfn_pgd(PFN_DOWN(__pa(p)), PAGE_TABLE));
> + }
> + } while (pgd_k++, vaddr = next, vaddr != end);
> + }
> +
> static void __init kasan_shallow_populate(void *start, void *end)
> {
> unsigned long vaddr = (unsigned long)start & PAGE_MASK;
> unsigned long vend = PAGE_ALIGN((unsigned long)end);
> - unsigned long pfn;
> - int index;
> - void *p;
> - pud_t *pud_dir, *pud_k;
> - pgd_t *pgd_dir, *pgd_k;
> - p4d_t *p4d_dir, *p4d_k;
> -
> - while (vaddr < vend) {
> - index = pgd_index(vaddr);
> - pfn = csr_read(CSR_SATP) & SATP_PPN;
> - pgd_dir = (pgd_t *)pfn_to_virt(pfn) + index;
> - pgd_k = init_mm.pgd + index;
> - pgd_dir = pgd_offset_k(vaddr);
> - set_pgd(pgd_dir, *pgd_k);
> -
> - p4d_dir = p4d_offset(pgd_dir, vaddr);
> - p4d_k = p4d_offset(pgd_k, vaddr);
> -
> - vaddr = (vaddr + PUD_SIZE) & PUD_MASK;
> - pud_dir = pud_offset(p4d_dir, vaddr);
> - pud_k = pud_offset(p4d_k, vaddr);
> -
> - if (pud_present(*pud_dir)) {
> - p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
> - pud_populate(&init_mm, pud_dir, p);
> - }
> - vaddr += PAGE_SIZE;
> - }
> +
> + kasan_shallow_populate_pgd(vaddr, vend);
> +
> + local_flush_tlb_all();
> }
>
> void __init kasan_init(void)
> {
> phys_addr_t _start, _end;
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