[flashrom] [PATCH] Handle denied access to cbtable gracefuly
Carl-Daniel Hailfinger
c-d.hailfinger.devel.2006 at gmx.net
Mon Feb 1 05:41:49 CET 2010
Stefan: Could you please test this one on Mac OS X? In theory it should
even allow us to kill the start=0x400 special case for Mac OS X.
Create a physical memory mapping function which requests cached readonly
memory. This should take care of picky Linux kernels which do not allow
uncached mappings to cached areas.
Handle mapping failure gracefully (no forced exit()) if the caller
specifies it.
Such cached areas which can handle mapping failure are DMI tables and
coreboot tables. On retry and repeated failure we just ignore those
tables. That is not perfect, but a lot better than aborting flashrom due
to an error in nonessential functionality.
This should fix flashrom on a sizable number of machines where it
currently aborts early.
Yes, I could have exploited a Linux kernel bug to "solve" this, but
relying on such bugs is not exactly the best idea.
Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>
Index: flashrom-physmap_graceful_error_cbtable/flash.h
===================================================================
--- flashrom-physmap_graceful_error_cbtable/flash.h (Revision 886)
+++ flashrom-physmap_graceful_error_cbtable/flash.h (Arbeitskopie)
@@ -343,6 +343,7 @@
/* physmap.c */
void *physmap(const char *descr, unsigned long phys_addr, size_t len);
+void *physmap_try_ro(const char *descr, unsigned long phys_addr, size_t len);
void physunmap(void *virt_addr, size_t len);
int setup_cpu_msr(int cpu);
void cleanup_cpu_msr(void);
Index: flashrom-physmap_graceful_error_cbtable/physmap.c
===================================================================
--- flashrom-physmap_graceful_error_cbtable/physmap.c (Revision 886)
+++ flashrom-physmap_graceful_error_cbtable/physmap.c (Arbeitskopie)
@@ -3,6 +3,7 @@
*
* Copyright (C) 2009 Peter Stuge <peter at stuge.se>
* Copyright (C) 2009 coresystems GmbH
+ * Copyright (C) 2010 Carl-Daniel Hailfinger
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@@ -36,6 +37,10 @@
return map_physical(phys_addr, len);
}
+/* The OS X driver does not differentiate between mapping types. */
+#define sys_physmap_rw_uncached sys_physmap
+#define sys_physmap_ro_cached sys_physmap
+
void physunmap(void *virt_addr, size_t len)
{
unmap_physical(virt_addr, len);
@@ -51,8 +56,10 @@
#endif
static int fd_mem = -1;
+static int fd_mem_cached = -1;
-void *sys_physmap(unsigned long phys_addr, size_t len)
+/* For MMIO access. Must be uncached, doesn't make sense to restrict to ro. */
+void *sys_physmap_rw_uncached(unsigned long phys_addr, size_t len)
{
void *virt_addr;
@@ -69,6 +76,26 @@
return MAP_FAILED == virt_addr ? NULL : virt_addr;
}
+/* For reading DMI/coreboot/whatever tables. We should never write, and we
+ * do not care about caching.
+ */
+void *sys_physmap_ro_cached(unsigned long phys_addr, size_t len)
+{
+ void *virt_addr;
+
+ if (-1 == fd_mem_cached) {
+ /* Open the memory device CACHED. */
+ if (-1 == (fd_mem_cached = open(MEM_DEV, O_RDWR))) {
+ perror("Critical error: open(" MEM_DEV ")");
+ exit(2);
+ }
+ }
+
+ virt_addr = mmap(0, len, PROT_READ, MAP_SHARED,
+ fd_mem_cached, (off_t)phys_addr);
+ return MAP_FAILED == virt_addr ? NULL : virt_addr;
+}
+
void physunmap(void *virt_addr, size_t len)
{
if (len == 0) {
@@ -80,7 +107,12 @@
}
#endif
-void *physmap(const char *descr, unsigned long phys_addr, size_t len)
+#define PHYSMAP_NOFAIL 0
+#define PHYSMAP_MAYFAIL 1
+#define PHYSMAP_RW 0
+#define PHYSMAP_RO 1
+
+void *physmap_common(const char *descr, unsigned long phys_addr, size_t len, int mayfail, int readonly)
{
void *virt_addr;
@@ -100,7 +132,11 @@
descr, (unsigned long)len, phys_addr);
}
- virt_addr = sys_physmap(phys_addr, len);
+ if (readonly) {
+ virt_addr = sys_physmap_ro_cached(phys_addr, len);
+ } else {
+ virt_addr = sys_physmap_rw_uncached(phys_addr, len);
+ }
if (NULL == virt_addr) {
if (NULL == descr)
@@ -114,12 +150,23 @@
fprintf(stderr, "You can override CONFIG_X86_PAT at boot with the nopat kernel parameter but\n");
fprintf(stderr, "disabling the other option unfortunately requires a kernel recompile. Sorry!\n");
}
- exit(3);
+ if (!mayfail)
+ exit(3);
}
return virt_addr;
}
+void *physmap(const char *descr, unsigned long phys_addr, size_t len)
+{
+ return physmap_common(descr, phys_addr, len, PHYSMAP_NOFAIL, PHYSMAP_RW);
+}
+
+void *physmap_try_ro(const char *descr, unsigned long phys_addr, size_t len)
+{
+ return physmap_common(descr, phys_addr, len, PHYSMAP_MAYFAIL, PHYSMAP_RO);
+}
+
#ifdef __linux__
/*
* Reading and writing to MSRs, however requires instructions rdmsr/wrmsr,
Index: flashrom-physmap_graceful_error_cbtable/cbtable.c
===================================================================
--- flashrom-physmap_graceful_error_cbtable/cbtable.c (Revision 886)
+++ flashrom-physmap_graceful_error_cbtable/cbtable.c (Arbeitskopie)
@@ -6,6 +6,7 @@
* (Written by Eric Biederman <ebiederman at lnxi.com> for Linux Networx)
* Copyright (C) 2006-2009 coresystems GmbH
* (Written by Stefan Reinauer <stepan at coresystems.de> for coresystems GmbH)
+ * Copyright (C) 2010 Carl-Daniel Hailfinger
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@@ -194,24 +195,36 @@
#define BYTES_TO_MAP (1024*1024)
int coreboot_init(void)
{
- uint8_t *table_area;
+ uint8_t *table_area = NULL;
unsigned long addr, start;
- struct lb_header *lb_table;
+ struct lb_header *lb_table = NULL;
struct lb_record *rec, *last;
#ifdef __DARWIN__
/* This is a hack. DirectIO fails to map physical address 0x00000000.
* Why?
+ * FIXME: This hack should be unnecessary with the low megabyte retries.
*/
start = 0x400;
#else
start = 0x0;
#endif
- table_area = physmap("low megabyte", start, BYTES_TO_MAP);
+ table_area = physmap_try_ro("low megabyte", start, BYTES_TO_MAP - start);
+ while (!table_area) {
+ msg_pinfo("Trying a smaller mapping.\n");
+ start += 0x400;
+ /* Outside lower 1 MB? Abort. */
+ if (start > 0x100000) {
+ msg_perr("Failed getting access to low megabyte. "
+ "Ignoring any coreboot tables.\n");
+ return -1;
+ }
+ table_area = physmap_try_ro("low megabyte", start, BYTES_TO_MAP - start);
+ }
lb_table = find_lb_table(table_area, 0x00000, 0x1000);
if (!lb_table)
- lb_table = find_lb_table(table_area, 0xf0000, BYTES_TO_MAP);
+ lb_table = find_lb_table(table_area, 0xf0000 - start, BYTES_TO_MAP - start);
if (lb_table) {
struct lb_forward *forward = (struct lb_forward *)
(((char *)lb_table) + lb_table->header_bytes);
@@ -219,7 +232,12 @@
start = forward->forward;
start &= ~(getpagesize() - 1);
physunmap(table_area, BYTES_TO_MAP);
- table_area = physmap("high tables", start, BYTES_TO_MAP);
+ table_area = physmap_try_ro("high tables", start, BYTES_TO_MAP);
+ if (!table_area) {
+ msg_perr("Failed getting access to coreboot "
+ "high tables.\n");
+ return -1;
+ }
lb_table = find_lb_table(table_area, 0x00000, 0x1000);
}
}
--
Developer quote of the year:
"We are juggling too many chainsaws and flaming arrows and tigers."
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