From 01522df346f846906eaf6ca57148641476209909 Mon Sep 17 00:00:00 2001 From: "Michael K. Johnson" Date: Fri, 27 Mar 2009 13:14:41 -0400 Subject: x86, setup: mark %esi as clobbered in E820 BIOS call Jordan Hargrave diagnosed a BIOS clobbering %esi in the E820 call. That particular BIOS has been fixed, but there is a possibility that this is responsible for other occasional reports of early boot failure, and it does not hurt to add %esi to the clobbers. -stable candidate patch. Cc: Justin Forbes Signed-off-by: Michael K Johnson Signed-off-by: H. Peter Anvin Cc: stable@kernel.org --- arch/x86/boot/memory.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'arch/x86/boot') diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c index 8c3c25f35578..a99dbbe77a0c 100644 --- a/arch/x86/boot/memory.c +++ b/arch/x86/boot/memory.c @@ -27,13 +27,14 @@ static int detect_memory_e820(void) do { size = sizeof(struct e820entry); - /* Important: %edx is clobbered by some BIOSes, - so it must be either used for the error output + /* Important: %edx and %esi are clobbered by some BIOSes, + so they must be either used for the error output or explicitly marked clobbered. */ asm("int $0x15; setc %0" : "=d" (err), "+b" (next), "=a" (id), "+c" (size), "=m" (*desc) - : "D" (desc), "d" (SMAP), "a" (0xe820)); + : "D" (desc), "d" (SMAP), "a" (0xe820) + : "esi"); /* BIOSes which terminate the chain with CF = 1 as opposed to %ebx = 0 don't always report the SMAP signature on -- cgit v1.2.3 From 32ec7fd08b597586774b92ac1cd2678021ccac1b Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Sat, 28 Mar 2009 13:53:26 -0700 Subject: x86, setup: preemptively save/restore edi and ebp around INT 15 E820 Impact: BIOS bugproofing Since there are BIOSes known to clobber %ebx and %esi for INT 15 E820, assume there is something out there clobbering %edi and/or %ebp too, and don't wait for it to fail. Signed-off-by: H. Peter Anvin --- arch/x86/boot/memory.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'arch/x86/boot') diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c index a99dbbe77a0c..fcdb10add9c8 100644 --- a/arch/x86/boot/memory.c +++ b/arch/x86/boot/memory.c @@ -20,7 +20,7 @@ static int detect_memory_e820(void) { int count = 0; u32 next = 0; - u32 size, id; + u32 size, id, edi; u8 err; struct e820entry *desc = boot_params.e820_map; @@ -29,10 +29,11 @@ static int detect_memory_e820(void) /* Important: %edx and %esi are clobbered by some BIOSes, so they must be either used for the error output - or explicitly marked clobbered. */ - asm("int $0x15; setc %0" + or explicitly marked clobbered. Given that, assume there + is something out there clobbering %ebp and %edi, too. */ + asm("pushl %%ebp; int $0x15; popl %%ebp; setc %0" : "=d" (err), "+b" (next), "=a" (id), "+c" (size), - "=m" (*desc) + "=D" (edi), "=m" (*desc) : "D" (desc), "d" (SMAP), "a" (0xe820) : "esi"); -- cgit v1.2.3 From c549e71d073a6e9a4847497344db28a784061455 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Sat, 28 Mar 2009 13:53:26 -0700 Subject: x86, setup: ACPI 3, BIOS workaround for E820-probing code Impact: ACPI 3 spec compliance, BIOS bug workaround The ACPI 3 spec added another field to the E820 buffer -- which is backwards incompatible, since it contains a validity bit. Furthermore, there has been at least one report of a BIOS which assumes that the buffer it is pointed at is the same buffer as for the previous E820 call. Therefore, read the data into a temporary buffer and copy the standard part of it if and only if the valid bit is set. Signed-off-by: H. Peter Anvin --- arch/x86/boot/memory.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) (limited to 'arch/x86/boot') diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c index fcdb10add9c8..d5d2360763dc 100644 --- a/arch/x86/boot/memory.c +++ b/arch/x86/boot/memory.c @@ -2,6 +2,7 @@ * * Copyright (C) 1991, 1992 Linus Torvalds * Copyright 2007 rPath, Inc. - All Rights Reserved + * Copyright 2009 Intel Corporation; author H. Peter Anvin * * This file is part of the Linux kernel, and is made available under * the terms of the GNU General Public License version 2. @@ -16,6 +17,11 @@ #define SMAP 0x534d4150 /* ASCII "SMAP" */ +struct e820_ext_entry { + struct e820entry std; + u32 ext_flags; +} __attribute__((packed)); + static int detect_memory_e820(void) { int count = 0; @@ -23,9 +29,10 @@ static int detect_memory_e820(void) u32 size, id, edi; u8 err; struct e820entry *desc = boot_params.e820_map; + static struct e820_ext_entry buf; /* static so it is zeroed */ do { - size = sizeof(struct e820entry); + size = sizeof buf; /* Important: %edx and %esi are clobbered by some BIOSes, so they must be either used for the error output @@ -33,8 +40,8 @@ static int detect_memory_e820(void) is something out there clobbering %ebp and %edi, too. */ asm("pushl %%ebp; int $0x15; popl %%ebp; setc %0" : "=d" (err), "+b" (next), "=a" (id), "+c" (size), - "=D" (edi), "=m" (*desc) - : "D" (desc), "d" (SMAP), "a" (0xe820) + "=D" (edi), "+m" (buf) + : "D" (&buf), "d" (SMAP), "a" (0xe820) : "esi"); /* BIOSes which terminate the chain with CF = 1 as opposed @@ -53,8 +60,14 @@ static int detect_memory_e820(void) break; } + /* ACPI 3.0 added the extended flags support. If bit 0 + in the extended flags is zero, we're supposed to simply + ignore the entry -- a backwards incompatible change! */ + if (size > 20 && !(buf.ext_flags & 1)) + continue; + + *desc++ = buf.std; count++; - desc++; } while (next && count < ARRAY_SIZE(boot_params.e820_map)); return boot_params.e820_entries = count; -- cgit v1.2.3 From cd670599b7b00d9263f6f11a05c0edeb9cbedaf3 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Wed, 1 Apr 2009 11:35:00 -0700 Subject: x86, setup: guard against pre-ACPI 3 e820 code not updating %ecx Impact: BIOS bug safety For pre-ACPI 3 BIOSes, pre-initialize the end of the e820 buffer just in case the BIOS returns an unchanged %ecx but without actually touching the ACPI 3 extended flags field. Signed-off-by: H. Peter Anvin --- arch/x86/boot/memory.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch/x86/boot') diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c index d5d2360763dc..5054c2ddd1a0 100644 --- a/arch/x86/boot/memory.c +++ b/arch/x86/boot/memory.c @@ -31,6 +31,12 @@ static int detect_memory_e820(void) struct e820entry *desc = boot_params.e820_map; static struct e820_ext_entry buf; /* static so it is zeroed */ + /* + * Set this here so that if the BIOS doesn't change this field + * but still doesn't change %ecx, we're still okay... + */ + buf.ext_flags = 1; + do { size = sizeof buf; -- cgit v1.2.3