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Message-ID: <20241018140052.665806-1-shorne@gmail.com>
Date: Fri, 18 Oct 2024 15:00:49 +0100
From: Stafford Horne <shorne@...il.com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Stafford Horne <shorne@...il.com>,
Jonas Bonn <jonas@...thpole.se>,
Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
Dawei Li <set_pte_at@...look.com>,
"Mike Rapoport (IBM)" <rppt@...nel.org>,
Baoquan He <bhe@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-openrisc@...r.kernel.org
Subject: [PATCH v2] openrisc: Implement fixmap to fix earlycon
With commit 53c98e35dcbc ("openrisc: mm: remove unneeded early ioremap
code") it was commented that early ioremap was not used in OpenRISC. I
acked this but was wrong, earlycon was using it. Earlycon setup now
fails with the below trace:
Kernel command line: earlycon
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at mm/ioremap.c:23
generic_ioremap_prot+0x118/0x130
Modules linked in:
CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted
6.11.0-rc5-00001-gce02fd891c38-dirty #141
Call trace:
[<(ptrval)>] dump_stack_lvl+0x7c/0x9c
[<(ptrval)>] dump_stack+0x1c/0x2c
[<(ptrval)>] __warn+0xb4/0x108
[<(ptrval)>] ? generic_ioremap_prot+0x118/0x130
[<(ptrval)>] warn_slowpath_fmt+0x60/0x98
[<(ptrval)>] generic_ioremap_prot+0x118/0x130
[<(ptrval)>] ioremap_prot+0x20/0x30
[<(ptrval)>] of_setup_earlycon+0xd4/0x2e0
[<(ptrval)>] early_init_dt_scan_chosen_stdout+0x18c/0x1c8
[<(ptrval)>] param_setup_earlycon+0x3c/0x60
[<(ptrval)>] do_early_param+0xb0/0x118
[<(ptrval)>] parse_args+0x184/0x4b8
[<(ptrval)>] ? start_kernel+0x0/0x78c
[<(ptrval)>] parse_early_options+0x40/0x50
[<(ptrval)>] ? do_early_param+0x0/0x118
[<(ptrval)>] parse_early_param+0x48/0x68
[<(ptrval)>] ? start_kernel+0x318/0x78c
[<(ptrval)>] ? start_kernel+0x0/0x78c
---[ end trace 0000000000000000 ]---
To fix this we could either implement early_ioremap again or implement
fixmap. In this patch we choose the later option of implementing basic
fixmap support.
While fixing this we also remove the old FIX_IOREMAP slots that were
used by early ioremap code. That code was also removed by commit
53c98e35dcbc ("openrisc: mm: remove unneeded early ioremap code") but
these definitions were not cleaned up.
Fixes: 53c98e35dcbc ("openrisc: mm: remove unneeded early ioremap code")
Signed-off-by: Stafford Horne <shorne@...il.com>
---
Changes since v1:
- Fix earlycon mis spelling in subject
- Add support for clearing pte entries on fixmap removal
- Add a tlb flush after updating the page table
- Use pgprot_t directly in map_page rather than converting
arch/openrisc/Kconfig | 3 +++
arch/openrisc/include/asm/fixmap.h | 21 ++++-------------
arch/openrisc/mm/init.c | 37 ++++++++++++++++++++++++++++++
3 files changed, 45 insertions(+), 16 deletions(-)
diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
index 69c0258700b2..3279ef457c57 100644
--- a/arch/openrisc/Kconfig
+++ b/arch/openrisc/Kconfig
@@ -65,6 +65,9 @@ config STACKTRACE_SUPPORT
config LOCKDEP_SUPPORT
def_bool y
+config FIX_EARLYCON_MEM
+ def_bool y
+
menu "Processor type and features"
choice
diff --git a/arch/openrisc/include/asm/fixmap.h b/arch/openrisc/include/asm/fixmap.h
index ecdb98a5839f..aaa6a26a3e92 100644
--- a/arch/openrisc/include/asm/fixmap.h
+++ b/arch/openrisc/include/asm/fixmap.h
@@ -26,29 +26,18 @@
#include <linux/bug.h>
#include <asm/page.h>
-/*
- * On OpenRISC we use these special fixed_addresses for doing ioremap
- * early in the boot process before memory initialization is complete.
- * This is used, in particular, by the early serial console code.
- *
- * It's not really 'fixmap', per se, but fits loosely into the same
- * paradigm.
- */
enum fixed_addresses {
- /*
- * FIX_IOREMAP entries are useful for mapping physical address
- * space before ioremap() is useable, e.g. really early in boot
- * before kmalloc() is working.
- */
-#define FIX_N_IOREMAPS 32
- FIX_IOREMAP_BEGIN,
- FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
+ FIX_EARLYCON_MEM_BASE,
__end_of_fixed_addresses
};
#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
/* FIXADDR_BOTTOM might be a better name here... */
#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
+#define FIXMAP_PAGE_IO PAGE_KERNEL_NOCACHE
+
+extern void __set_fixmap(enum fixed_addresses idx,
+ phys_addr_t phys, pgprot_t flags);
#include <asm-generic/fixmap.h>
diff --git a/arch/openrisc/mm/init.c b/arch/openrisc/mm/init.c
index 1dcd78c8f0e9..d0cb1a0126f9 100644
--- a/arch/openrisc/mm/init.c
+++ b/arch/openrisc/mm/init.c
@@ -207,6 +207,43 @@ void __init mem_init(void)
return;
}
+static int __init map_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
+{
+ p4d_t *p4d;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ p4d = p4d_offset(pgd_offset_k(va), va);
+ pud = pud_offset(p4d, va);
+ pmd = pmd_offset(pud, va);
+ pte = pte_alloc_kernel(pmd, va);
+
+ if (pte == NULL)
+ return -ENOMEM;
+
+ if (pgprot_val(prot))
+ set_pte_at(&init_mm, va, pte, pfn_pte(pa >> PAGE_SHIFT, prot));
+ else
+ pte_clear(&init_mm, va, pte);
+
+ local_flush_tlb_page(NULL, va);
+ return 0;
+}
+
+void __init __set_fixmap(enum fixed_addresses idx,
+ phys_addr_t phys, pgprot_t prot)
+{
+ unsigned long address = __fix_to_virt(idx);
+
+ if (idx >= __end_of_fixed_addresses) {
+ BUG();
+ return;
+ }
+
+ map_page(address, phys, prot);
+}
+
static const pgprot_t protection_map[16] = {
[VM_NONE] = PAGE_NONE,
[VM_READ] = PAGE_READONLY_X,
--
2.47.0
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