[PATCH] RISC-V: Add kernel image sections to the resource tree
Atish Patra
atishp at atishpatra.org
Wed Dec 23 15:02:24 EST 2020
On Tue, Dec 22, 2020 at 3:59 PM Nick Kossifidis <mick at ics.forth.gr> wrote:
>
> Στις 2020-12-19 01:52, Atish Patra έγραψε:
> > On Thu, Nov 5, 2020 at 10:37 AM Palmer Dabbelt <palmer at dabbelt.com>
> > wrote:
> >>
> >> On Mon, 12 Oct 2020 07:24:10 PDT (-0700), mick at ics.forth.gr wrote:
> >> > This patch (previously part of my kexec/kdump series) populates
> >> > /proc/iomem with the various sections of the kernel image. We need
> >> > this for kexec-tools to be able to prepare the crashkernel image
> >> > for kdump to work. Since resource tree initialization is not
> >> > related to memory initialization I added the code to kernel/setup.c
> >> > and removed the original code (derived from the arm64 tree) from
> >> > mm/init.c.
> >> >
> >> > Signed-off-by: Nick Kossifidis <mick at ics.forth.gr>
> >> > ---
> >> > arch/riscv/kernel/setup.c | 160 ++++++++++++++++++++++++++++++++++++++
> >> > arch/riscv/mm/init.c | 27 -------
> >> > 2 files changed, 160 insertions(+), 27 deletions(-)
> >> >
> >> > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> >> > index 2c6dd3293..450f0142f 100644
> >> > --- a/arch/riscv/kernel/setup.c
> >> > +++ b/arch/riscv/kernel/setup.c
> >> > @@ -4,6 +4,8 @@
> >> > * Chen Liqin <liqin.chen at sunplusct.com>
> >> > * Lennox Wu <lennox.wu at sunplusct.com>
> >> > * Copyright (C) 2012 Regents of the University of California
> >> > + * Copyright (C) 2020 FORTH-ICS/CARV
> >> > + * Nick Kossifidis <mick at ics.forth.gr>
> >> > */
> >> >
> >> > #include <linux/init.h>
> >> > @@ -48,6 +50,163 @@ atomic_t hart_lottery __section(.sdata);
> >> > unsigned long boot_cpu_hartid;
> >> > static DEFINE_PER_CPU(struct cpu, cpu_devices);
> >> >
> >> > +/*
> >> > + * Place kernel memory regions on the resource tree so that
> >> > + * kexec-tools can retrieve them from /proc/iomem. While there
> >> > + * also add "System RAM" regions for compatibility with other
> >> > + * archs, and the rest of the known regions for completeness.
> >> > + */
> >> > +static struct resource code_res = { .name = "Kernel code", };
> >> > +static struct resource data_res = { .name = "Kernel data", };
> >> > +static struct resource rodata_res = { .name = "Kernel rodata", };
> >> > +static struct resource bss_res = { .name = "Kernel bss", };
> >> > +
> >> > +static int __init add_resource(struct resource *parent,
> >> > + struct resource *res)
> >> > +{
> >> > + int ret = 0;
> >> > +
> >> > + ret = insert_resource(parent, res);
> >> > + if (ret < 0) {
> >> > + pr_err("Failed to add a %s resource at %llx\n",
> >> > + res->name, (unsigned long long) res->start);
> >> > + return ret;
> >> > + }
> >> > +
> >> > + return 1;
> >> > +}
> >> > +
> >> > +static int __init add_kernel_resources(struct resource *res)
> >> > +{
> >> > + int ret = 0;
> >> > +
> >> > + /*
> >> > + * The memory region of the kernel image is continuous and
> >> > + * was reserved on setup_bootmem, find it here and register
> >> > + * it as a resource, then register the various segments of
> >> > + * the image as child nodes
> >> > + */
> >> > + if (!(res->start <= code_res.start && res->end >= data_res.end))
> >> > + return 0;
> >> > +
> >> > + res->name = "Kernel image";
> >> > + res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> >> > +
> >> > + /*
> >> > + * We removed a part of this region on setup_bootmem so
> >> > + * we need to expand the resource for the bss to fit in.
> >> > + */
> >> > + res->end = bss_res.end;
> >> > +
> >> > + ret = add_resource(&iomem_resource, res);
> >> > + if (ret < 0)
> >> > + return ret;
> >> > +
> >> > + ret = add_resource(res, &code_res);
> >> > + if (ret < 0)
> >> > + return ret;
> >> > +
> >> > + ret = add_resource(res, &rodata_res);
> >> > + if (ret < 0)
> >> > + return ret;
> >> > +
> >> > + ret = add_resource(res, &data_res);
> >> > + if (ret < 0)
> >> > + return ret;
> >> > +
> >> > + ret = add_resource(res, &bss_res);
> >> > +
> >> > + return ret;
> >> > +}
> >> > +
> >> > +static void __init init_resources(void)
> >> > +{
> >> > + struct memblock_region *region = NULL;
> >> > + struct resource *res = NULL;
> >> > + int ret = 0;
> >> > +
> >> > + code_res.start = __pa_symbol(_text);
> >> > + code_res.end = __pa_symbol(_etext) - 1;
> >> > + code_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> >> > +
> >> > + rodata_res.start = __pa_symbol(__start_rodata);
> >> > + rodata_res.end = __pa_symbol(__end_rodata) - 1;
> >> > + rodata_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> >> > +
> >> > + data_res.start = __pa_symbol(_data);
> >> > + data_res.end = __pa_symbol(_edata) - 1;
> >> > + data_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> >> > +
> >> > + bss_res.start = __pa_symbol(__bss_start);
> >> > + bss_res.end = __pa_symbol(__bss_stop) - 1;
> >> > + bss_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> >> > +
> >> > + /*
> >> > + * Start by adding the reserved regions, if they overlap
> >> > + * with /memory regions, insert_resource later on will take
> >> > + * care of it.
> >> > + */
> >> > + for_each_memblock(reserved, region) {
> >> > + res = memblock_alloc(sizeof(struct resource), SMP_CACHE_BYTES);
> >
> > Is there a specific reason to invoke memblock_alloc while iterating
> > reserved regions ?
> > memblock_alloc also adds calls memblock_reserve. So we are modifying
> > the reserved region entries
> > while iterating it. It resulted in below warning for rv32.
> >
> > [ 0.000000] ------------[ cut here ]------------
> > [ 0.000000] WARNING: CPU: 0 PID: 0 at kernel/resource.c:795
> > __insert_resource+0x8e/0xd0
> > [ 0.000000] Modules linked in:
> > [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted
> > 5.10.0-00022-ge20097fb37e2-dirty #549
> > [ 0.000000] epc: c00125c2 ra : c001262c sp : c1c01f50
> > [ 0.000000] gp : c1d456e0 tp : c1c0a980 t0 : ffffcf20
> > [ 0.000000] t1 : 00000000 t2 : 00000000 s0 : c1c01f60
> > [ 0.000000] s1 : ffffcf00 a0 : ffffff00 a1 : c1c0c0c4
> > [ 0.000000] a2 : 80c12b15 a3 : 80402000 a4 : 80402000
> > [ 0.000000] a5 : c1c0c0c4 a6 : 80c12b15 a7 : f5faf600
> > [ 0.000000] s2 : c1c0c0c4 s3 : c1c0e000 s4 : c1009a80
> > [ 0.000000] s5 : c1c0c000 s6 : c1d48000 s7 : c1613b4c
> > [ 0.000000] s8 : 00000fff s9 : 80000200 s10: c1613b40
> > [ 0.000000] s11: 00000000 t3 : c1d4a000 t4 : ffffffff
> > [ 0.000000] t5 : c1008e38 t6 : 00000001
> > [ 0.000000] status: 00000100 badaddr: 00000000 cause: 00000003
> > [ 0.000000] irq event stamp: 0
> > [ 0.000000] hardirqs last enabled at (0): [<00000000>] 0x0
> > [ 0.000000] hardirqs last disabled at (0): [<00000000>] 0x0
> > [ 0.000000] softirqs last enabled at (0): [<00000000>] 0x0
> > [ 0.000000] softirqs last disabled at (0): [<00000000>] 0x0
> > [ 0.000000] random: get_random_bytes called from __warn+0xd8/0x11e
> > with crng_init=0
> > [ 0.000000] ---[ end trace 0000000000000000 ]---
> > [ 0.000000] Failed to add a Kernel code resource at 80402000
> >
> > Here is the fix that works:
> > --- a/arch/riscv/kernel/setup.c
> > +++ b/arch/riscv/kernel/setup.c
> > @@ -127,7 +127,9 @@ static void __init init_resources(void)
> > {
> > struct memblock_region *region = NULL;
> > struct resource *res = NULL;
> > - int ret = 0;
> > + int ret = 0, i = 0;
> > + int num_mem_res;
> > + struct resource *mem_res;
> >
> > code_res.start = __pa_symbol(_text);
> > code_res.end = __pa_symbol(_etext) - 1;
> > @@ -145,16 +147,17 @@ static void __init init_resources(void)
> > bss_res.end = __pa_symbol(__bss_stop) - 1;
> > bss_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> >
> > + num_mem_res = memblock.memory.cnt + memblock.reserved.cnt;
> > + mem_res = memblock_alloc(num_mem_res * sizeof(*mem_res),
> > SMP_CACHE_BYTES);
> > + if (!mem_res)
> > + panic("%s: Failed to allocate %zu bytes\n", __func__,
> > num_mem_res * sizeof(*mem_res));
> > /*
> > * Start by adding the reserved regions, if they overlap
> > * with /memory regions, insert_resource later on will take
> > * care of it.
> > */
> > for_each_reserved_mem_region(region) {
> > - res = memblock_alloc(sizeof(struct resource),
> > SMP_CACHE_BYTES);
> > - if (!res)
> > - panic("%s: Failed to allocate %zu bytes\n",
> > __func__,
> > - sizeof(struct resource));
> > + res = &mem_res[i++];
> >
> > res->name = "Reserved";
> > res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
> > @@ -181,11 +184,8 @@ static void __init init_resources(void)
> >
> > /* Add /memory regions to the resource tree */
> > for_each_mem_region(region) {
> > - res = memblock_alloc(sizeof(struct resource),
> > SMP_CACHE_BYTES);
> > - if (!res)
> > - panic("%s: Failed to allocate %zu bytes\n",
> > __func__,
> > - sizeof(struct resource));
> >
> > + res = &mem_res[i++];
> >
> > If this looks okay to you, I will send the patch.
> >
>
> The problem is that we don't want to include all reserved regions within
> /memory such as the device tree or initramfs, since they'll get modified
> and/or freed later on. So pre-allocating resources for all reserved
> regions doesn't seem the right thing to do. My goal here was to allocate
> a resource on each itteration and free it if not needed / on failure, I
> free the failed resource on failure but not if it's not needed as you
> noted.
>
> As for the issue of memblock_alloc() calling memblock_reserve(), we
> don't add any new reserved regions at this point directly through
> memblock_reserve(), and memblock_reserve() will run on neighboring
> regions that memblock_merge_regions() will later on merge together, so
> it'll work on a single growing region instead of creating new ones. The
> issue is that we call memblock_alloc() for the first time inside the
> loop and for_each_mem_region() macro uses pointer arithmetic on the
> initial array of reserved memblocks,
Yes. We also need to do that for_each_reserved_mem_region as well.
Adding that to your diff will be exactly similar to mine.
> for_each_memblock_type() macro but it's not on memblock.h anymore OR we
> could call memblock_alloc() before the loop so that the array is not
> expanded while itterating.
>
> How about this, does it work for you ?:
>
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index 1d85e9bf7..460cfddb7 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -127,8 +127,16 @@ static void __init init_resources(void)
> {
> struct memblock_region *region = NULL;
> struct resource *res = NULL;
> + struct resource *mem_resources = NULL;
> + size_t mem_resources_sz = 0;
> int ret = 0;
>
> + mem_resources_sz = memblock.memory.cnt * sizeof(struct resource);
> + mem_resources = memblock_alloc(mem_resources_sz, SMP_CACHE_BYTES);
> + if (!mem_resources)
> + panic("%s: Failed to allocate %zu bytes\n", __func__,
> + sizeof(struct resource));
> +
> code_res.start = __pa_symbol(_text);
> code_res.end = __pa_symbol(_etext) - 1;
> code_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> @@ -171,20 +179,21 @@ static void __init init_resources(void)
> * Ignore any other reserved regions within
> * system memory.
> */
> - if (memblock_is_memory(res->start))
> + if (memblock_is_memory(res->start)) {
> + memblock_free((phys_addr_t) res, sizeof(struct resource));
> continue;
> + }
>
> ret = add_resource(&iomem_resource, res);
> - if (ret < 0)
> + if (ret < 0) {
> + memblock_free((phys_addr_t) res, sizeof(struct resource));
> goto error;
> + }
> }
>
> /* Add /memory regions to the resource tree */
> for_each_mem_region(region) {
> - res = memblock_alloc(sizeof(struct resource), SMP_CACHE_BYTES);
> - if (!res)
> - panic("%s: Failed to allocate %zu bytes\n", __func__,
> - sizeof(struct resource));
> + res = mem_resources++;
>
> if (unlikely(memblock_is_nomap(region))) {
> res->name = "Reserved";
> @@ -205,9 +214,9 @@ static void __init init_resources(void)
> return;
>
> error:
> - memblock_free((phys_addr_t) res, sizeof(struct resource));
> /* Better an empty resource tree than an inconsistent one */
> release_child_resources(&iomem_resource);
> + memblock_free((phys_addr_t) mem_resources, mem_resources_sz);
> }
>
> Regards,
> Nick
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
--
Regards,
Atish
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