108 lines
3.8 KiB
Diff
108 lines
3.8 KiB
Diff
From 48342ae751c797ac73ac9c894b3f312df18ffd21 Mon Sep 17 00:00:00 2001
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From: Geert Uytterhoeven <geert+renesas@glider.be>
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Date: Wed, 15 Sep 2021 13:46:20 +0100
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Subject: [PATCH] ARM: 9124/1: uncompress: Parse "linux,usable-memory-range" DT
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property
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Add support for parsing the "linux,usable-memory-range" DT property.
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This property is used to describe the usable memory reserved for the
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crash dump kernel, and thus makes the memory reservation explicit.
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If present, Linux no longer needs to mask the program counter, and rely
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on the "mem=" kernel parameter to obtain the start and size of usable
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memory.
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For backwards compatibility, the traditional method to derive the start
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of memory is still used if "linux,usable-memory-range" is absent.
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Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
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Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
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Signed-off-by: Daniel Danzberger <daniel@dd-wrt.com>
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---
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.../arm/boot/compressed/fdt_check_mem_start.c | 48 ++++++++++++++++---
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1 file changed, 42 insertions(+), 6 deletions(-)
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--- a/arch/arm/boot/compressed/fdt_check_mem_start.c
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+++ b/arch/arm/boot/compressed/fdt_check_mem_start.c
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@@ -55,16 +55,17 @@ static uint64_t get_val(const fdt32_t *c
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* DTB, and, if out-of-range, replace it by the real start address.
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* To preserve backwards compatibility (systems reserving a block of memory
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* at the start of physical memory, kdump, ...), the traditional method is
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- * always used if it yields a valid address.
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+ * used if it yields a valid address, unless the "linux,usable-memory-range"
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+ * property is present.
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*
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* Return value: start address of physical memory to use
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*/
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uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt)
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{
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- uint32_t addr_cells, size_cells, base;
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+ uint32_t addr_cells, size_cells, usable_base, base;
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uint32_t fdt_mem_start = 0xffffffff;
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- const fdt32_t *reg, *endp;
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- uint64_t size, end;
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+ const fdt32_t *usable, *reg, *endp;
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+ uint64_t size, usable_end, end;
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const char *type;
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int offset, len;
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@@ -80,6 +81,27 @@ uint32_t fdt_check_mem_start(uint32_t me
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if (addr_cells > 2 || size_cells > 2)
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return mem_start;
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+ /*
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+ * Usable memory in case of a crash dump kernel
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+ * This property describes a limitation: memory within this range is
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+ * only valid when also described through another mechanism
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+ */
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+ usable = get_prop(fdt, "/chosen", "linux,usable-memory-range",
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+ (addr_cells + size_cells) * sizeof(fdt32_t));
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+ if (usable) {
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+ size = get_val(usable + addr_cells, size_cells);
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+ if (!size)
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+ return mem_start;
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+
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+ if (addr_cells > 1 && fdt32_ld(usable)) {
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+ /* Outside 32-bit address space */
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+ return mem_start;
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+ }
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+
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+ usable_base = fdt32_ld(usable + addr_cells - 1);
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+ usable_end = usable_base + size;
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+ }
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+
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/* Walk all memory nodes and regions */
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for (offset = fdt_next_node(fdt, -1, NULL); offset >= 0;
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offset = fdt_next_node(fdt, offset, NULL)) {
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@@ -107,7 +129,20 @@ uint32_t fdt_check_mem_start(uint32_t me
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base = fdt32_ld(reg + addr_cells - 1);
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end = base + size;
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- if (mem_start >= base && mem_start < end) {
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+ if (usable) {
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+ /*
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+ * Clip to usable range, which takes precedence
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+ * over mem_start
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+ */
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+ if (base < usable_base)
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+ base = usable_base;
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+
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+ if (end > usable_end)
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+ end = usable_end;
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+
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+ if (end <= base)
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+ continue;
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+ } else if (mem_start >= base && mem_start < end) {
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/* Calculated address is valid, use it */
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return mem_start;
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}
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@@ -123,7 +158,8 @@ uint32_t fdt_check_mem_start(uint32_t me
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}
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/*
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- * The calculated address is not usable.
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+ * The calculated address is not usable, or was overridden by the
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+ * "linux,usable-memory-range" property.
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* Use the lowest usable physical memory address from the DTB instead,
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* and make sure this is a multiple of 2 MiB for phys/virt patching.
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*/
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