131 lines
4.5 KiB
Diff
131 lines
4.5 KiB
Diff
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Patrick Steinhardt <ps@pks.im>
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Date: Thu, 21 Apr 2022 15:24:18 +1000
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Subject: [PATCH] mm: Allow dynamically requesting additional memory regions
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Currently, all platforms will set up their heap on initialization of the
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platform code. While this works mostly fine, it poses some limitations
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on memory management on us. Most notably, allocating big chunks of
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memory in the gigabyte range would require us to pre-request this many
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bytes from the firmware and add it to the heap from the beginning on
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some platforms like EFI. As this isn't needed for most configurations,
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it is inefficient and may even negatively impact some usecases when,
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e.g., chainloading. Nonetheless, allocating big chunks of memory is
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required sometimes, where one example is the upcoming support for the
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Argon2 key derival function in LUKS2.
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In order to avoid pre-allocating big chunks of memory, this commit
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implements a runtime mechanism to add more pages to the system. When
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a given allocation cannot be currently satisfied, we'll call a given
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callback set up by the platform's own memory management subsystem,
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asking it to add a memory area with at least "n" bytes. If this
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succeeds, we retry searching for a valid memory region, which should
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now succeed.
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If this fails, we try asking for "n" bytes, possibly spread across
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multiple regions, in hopes that region merging means that we end up
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with enough memory for things to work out.
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Signed-off-by: Patrick Steinhardt <ps@pks.im>
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Signed-off-by: Daniel Axtens <dja@axtens.net>
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Tested-by: Stefan Berger <stefanb@linux.ibm.com>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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Tested-by: Patrick Steinhardt <ps@pks.im>
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(cherry picked from commit 887f98f0db43e33fba4ec1f85e42fae1185700bc)
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---
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grub-core/kern/mm.c | 30 ++++++++++++++++++++++++++++++
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include/grub/mm.h | 18 ++++++++++++++++++
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2 files changed, 48 insertions(+)
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diff --git a/grub-core/kern/mm.c b/grub-core/kern/mm.c
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index 1825dc8289..f2e27f263b 100644
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--- a/grub-core/kern/mm.c
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+++ b/grub-core/kern/mm.c
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@@ -28,6 +28,9 @@
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- multiple regions may be used as free space. They may not be
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contiguous.
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+ - if existing regions are insufficient to satisfy an allocation, a new
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+ region can be requested from firmware.
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+
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Regions are managed by a singly linked list, and the meta information is
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stored in the beginning of each region. Space after the meta information
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is used to allocate memory.
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@@ -81,6 +84,7 @@
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grub_mm_region_t grub_mm_base;
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+grub_mm_add_region_func_t grub_mm_add_region_fn;
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/* Get a header from the pointer PTR, and set *P and *R to a pointer
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to the header and a pointer to its region, respectively. PTR must
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@@ -444,6 +448,32 @@ grub_memalign (grub_size_t align, grub_size_t size)
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count++;
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goto again;
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+ case 1:
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+ /* Request additional pages, contiguous */
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+ count++;
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+
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+ if (grub_mm_add_region_fn != NULL &&
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+ grub_mm_add_region_fn (size, GRUB_MM_ADD_REGION_CONSECUTIVE) == GRUB_ERR_NONE)
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+ goto again;
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+
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+ /* fallthrough */
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+
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+ case 2:
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+ /* Request additional pages, anything at all */
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+ count++;
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+
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+ if (grub_mm_add_region_fn != NULL)
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+ {
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+ /*
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+ * Try again even if this fails, in case it was able to partially
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+ * satisfy the request
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+ */
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+ grub_mm_add_region_fn (size, GRUB_MM_ADD_REGION_NONE);
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+ goto again;
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+ }
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+
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+ /* fallthrough */
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+
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default:
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break;
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}
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diff --git a/include/grub/mm.h b/include/grub/mm.h
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index d81623d226..7c6f925ffd 100644
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--- a/include/grub/mm.h
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+++ b/include/grub/mm.h
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@@ -20,6 +20,7 @@
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#ifndef GRUB_MM_H
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#define GRUB_MM_H 1
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+#include <grub/err.h>
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#include <grub/types.h>
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#include <grub/symbol.h>
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#include <grub/err.h>
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@@ -29,6 +30,23 @@
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# define NULL ((void *) 0)
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#endif
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+#define GRUB_MM_ADD_REGION_NONE 0
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+#define GRUB_MM_ADD_REGION_CONSECUTIVE (1 << 0)
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+
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+/*
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+ * Function used to request memory regions of `grub_size_t` bytes. The second
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+ * parameter is a bitfield of `GRUB_MM_ADD_REGION` flags.
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+ */
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+typedef grub_err_t (*grub_mm_add_region_func_t) (grub_size_t, unsigned int);
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+
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+/*
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+ * Set this function pointer to enable adding memory-regions at runtime in case
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+ * a memory allocation cannot be satisfied with existing regions.
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+ */
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+#ifndef GRUB_MACHINE_EMU
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+extern grub_mm_add_region_func_t EXPORT_VAR(grub_mm_add_region_fn);
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+#endif
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+
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void grub_mm_init_region (void *addr, grub_size_t size);
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void *EXPORT_FUNC(grub_calloc) (grub_size_t nmemb, grub_size_t size);
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void *EXPORT_FUNC(grub_malloc) (grub_size_t size);
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