arm64: Update the Image header
Currently the kernel Image is stripped of everything past the initial
stack, and at runtime the memory is initialised and used by the kernel.
This makes the effective minimum memory footprint of the kernel larger
than the size of the loaded binary, though bootloaders have no mechanism
to identify how large this minimum memory footprint is. This makes it
difficult to choose safe locations to place both the kernel and other
binaries required at boot (DTB, initrd, etc), such that the kernel won't
clobber said binaries or other reserved memory during initialisation.
Additionally when big endian support was added the image load offset was
overlooked, and is currently of an arbitrary endianness, which makes it
difficult for bootloaders to make use of it. It seems that bootloaders
aren't respecting the image load offset at present anyway, and are
assuming that offset 0x80000 will always be correct.
This patch adds an effective image size to the kernel header which
describes the amount of memory from the start of the kernel Image binary
which the kernel expects to use before detecting memory and handling any
memory reservations. This can be used by bootloaders to choose suitable
locations to load the kernel and/or other binaries such that the kernel
will not clobber any memory unexpectedly. As before, memory reservations
are required to prevent the kernel from clobbering these locations
later.
Both the image load offset and the effective image size are forced to be
little-endian regardless of the native endianness of the kernel to
enable bootloaders to load a kernel of arbitrary endianness. Bootloaders
which wish to make use of the load offset can inspect the effective
image size field for a non-zero value to determine if the offset is of a
known endianness. To enable software to determine the endinanness of the
kernel as may be required for certain use-cases, a new flags field (also
little-endian) is added to the kernel header to export this information.
The documentation is updated to clarify these details. To discourage
future assumptions regarding the value of text_offset, the value at this
point in time is removed from the main flow of the documentation (though
kept as a compatibility note). Some minor formatting issues in the
documentation are also corrected.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Tom Rini <trini@ti.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Kevin Hilman <kevin.hilman@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-06-24 19:51:36 +04:00
|
|
|
/*
|
|
|
|
|
* Linker script macros to generate Image header fields.
|
|
|
|
|
*
|
|
|
|
|
* Copyright (C) 2014 ARM Ltd.
|
|
|
|
|
*
|
|
|
|
|
* This program is free software; you can redistribute it and/or modify
|
|
|
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
|
|
|
* published by the Free Software Foundation.
|
|
|
|
|
*
|
|
|
|
|
* This program is distributed in the hope that it will be useful,
|
|
|
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
|
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
|
|
|
* GNU General Public License for more details.
|
|
|
|
|
*
|
|
|
|
|
* You should have received a copy of the GNU General Public License
|
|
|
|
|
* along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
|
*/
|
|
|
|
|
#ifndef __ASM_IMAGE_H
|
|
|
|
|
#define __ASM_IMAGE_H
|
|
|
|
|
|
|
|
|
|
#ifndef LINKER_SCRIPT
|
|
|
|
|
#error This file should only be included in vmlinux.lds.S
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* There aren't any ELF relocations we can use to endian-swap values known only
|
|
|
|
|
* at link time (e.g. the subtraction of two symbol addresses), so we must get
|
|
|
|
|
* the linker to endian-swap certain values before emitting them.
|
|
|
|
|
*/
|
|
|
|
|
#ifdef CONFIG_CPU_BIG_ENDIAN
|
|
|
|
|
#define DATA_LE64(data) \
|
|
|
|
|
((((data) & 0x00000000000000ff) << 56) | \
|
|
|
|
|
(((data) & 0x000000000000ff00) << 40) | \
|
|
|
|
|
(((data) & 0x0000000000ff0000) << 24) | \
|
|
|
|
|
(((data) & 0x00000000ff000000) << 8) | \
|
|
|
|
|
(((data) & 0x000000ff00000000) >> 8) | \
|
|
|
|
|
(((data) & 0x0000ff0000000000) >> 24) | \
|
|
|
|
|
(((data) & 0x00ff000000000000) >> 40) | \
|
|
|
|
|
(((data) & 0xff00000000000000) >> 56))
|
|
|
|
|
#else
|
|
|
|
|
#define DATA_LE64(data) ((data) & 0xffffffffffffffff)
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
#ifdef CONFIG_CPU_BIG_ENDIAN
|
|
|
|
|
#define __HEAD_FLAG_BE 1
|
|
|
|
|
#else
|
|
|
|
|
#define __HEAD_FLAG_BE 0
|
|
|
|
|
#endif
|
|
|
|
|
|
2015-10-19 16:19:36 +03:00
|
|
|
#define __HEAD_FLAG_PAGE_SIZE ((PAGE_SHIFT - 10) / 2)
|
|
|
|
|
|
|
|
|
|
#define __HEAD_FLAGS ((__HEAD_FLAG_BE << 0) | \
|
|
|
|
|
(__HEAD_FLAG_PAGE_SIZE << 1))
|
arm64: Update the Image header
Currently the kernel Image is stripped of everything past the initial
stack, and at runtime the memory is initialised and used by the kernel.
This makes the effective minimum memory footprint of the kernel larger
than the size of the loaded binary, though bootloaders have no mechanism
to identify how large this minimum memory footprint is. This makes it
difficult to choose safe locations to place both the kernel and other
binaries required at boot (DTB, initrd, etc), such that the kernel won't
clobber said binaries or other reserved memory during initialisation.
Additionally when big endian support was added the image load offset was
overlooked, and is currently of an arbitrary endianness, which makes it
difficult for bootloaders to make use of it. It seems that bootloaders
aren't respecting the image load offset at present anyway, and are
assuming that offset 0x80000 will always be correct.
This patch adds an effective image size to the kernel header which
describes the amount of memory from the start of the kernel Image binary
which the kernel expects to use before detecting memory and handling any
memory reservations. This can be used by bootloaders to choose suitable
locations to load the kernel and/or other binaries such that the kernel
will not clobber any memory unexpectedly. As before, memory reservations
are required to prevent the kernel from clobbering these locations
later.
Both the image load offset and the effective image size are forced to be
little-endian regardless of the native endianness of the kernel to
enable bootloaders to load a kernel of arbitrary endianness. Bootloaders
which wish to make use of the load offset can inspect the effective
image size field for a non-zero value to determine if the offset is of a
known endianness. To enable software to determine the endinanness of the
kernel as may be required for certain use-cases, a new flags field (also
little-endian) is added to the kernel header to export this information.
The documentation is updated to clarify these details. To discourage
future assumptions regarding the value of text_offset, the value at this
point in time is removed from the main flow of the documentation (though
kept as a compatibility note). Some minor formatting issues in the
documentation are also corrected.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Tom Rini <trini@ti.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Kevin Hilman <kevin.hilman@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-06-24 19:51:36 +04:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* These will output as part of the Image header, which should be little-endian
|
|
|
|
|
* regardless of the endianness of the kernel. While constant values could be
|
|
|
|
|
* endian swapped in head.S, all are done here for consistency.
|
|
|
|
|
*/
|
|
|
|
|
#define HEAD_SYMBOLS \
|
|
|
|
|
_kernel_size_le = DATA_LE64(_end - _text); \
|
|
|
|
|
_kernel_offset_le = DATA_LE64(TEXT_OFFSET); \
|
|
|
|
|
_kernel_flags_le = DATA_LE64(__HEAD_FLAGS);
|
|
|
|
|
|
2015-10-08 22:02:04 +03:00
|
|
|
#ifdef CONFIG_EFI
|
|
|
|
|
|
arm64: hide __efistub_ aliases from kallsyms
Commit e8f3010f7326 ("arm64/efi: isolate EFI stub from the kernel
proper") isolated the EFI stub code from the kernel proper by prefixing
all of its symbols with __efistub_, and selectively allowing access to
core kernel symbols from the stub by emitting __efistub_ aliases for
functions and variables that the stub can access legally.
As an unintended side effect, these aliases are emitted into the
kallsyms symbol table, which means they may turn up in backtraces,
e.g.,
...
PC is at __efistub_memset+0x108/0x200
LR is at fixup_init+0x3c/0x48
...
[<ffffff8008328608>] __efistub_memset+0x108/0x200
[<ffffff8008094dcc>] free_initmem+0x2c/0x40
[<ffffff8008645198>] kernel_init+0x20/0xe0
[<ffffff8008085cd0>] ret_from_fork+0x10/0x40
The backtrace in question has nothing to do with the EFI stub, but
simply returns one of the several aliases of memset() that have been
recorded in the kallsyms table. This is undesirable, since it may
suggest to people who are not aware of this that the issue they are
seeing is somehow EFI related.
So hide the __efistub_ aliases from kallsyms, by emitting them as
absolute linker symbols explicitly. The distinction between those
and section relative symbols is completely irrelevant to these
definitions, and to the final link we are performing when these
definitions are being taken into account (the distinction is only
relevant to symbols defined inside a section definition when performing
a partial link), and so the resulting values are identical to the
original ones. Since absolute symbols are ignored by kallsyms, this
will result in these values to be omitted from its symbol table.
After this patch, the backtrace generated from the same address looks
like this:
...
PC is at __memset+0x108/0x200
LR is at fixup_init+0x3c/0x48
...
[<ffffff8008328608>] __memset+0x108/0x200
[<ffffff8008094dcc>] free_initmem+0x2c/0x40
[<ffffff8008645198>] kernel_init+0x20/0xe0
[<ffffff8008085cd0>] ret_from_fork+0x10/0x40
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-01-15 15:28:57 +03:00
|
|
|
/*
|
|
|
|
|
* Prevent the symbol aliases below from being emitted into the kallsyms
|
|
|
|
|
* table, by forcing them to be absolute symbols (which are conveniently
|
|
|
|
|
* ignored by scripts/kallsyms) rather than section relative symbols.
|
|
|
|
|
* The distinction is only relevant for partial linking, and only for symbols
|
|
|
|
|
* that are defined within a section declaration (which is not the case for
|
|
|
|
|
* the definitions below) so the resulting values will be identical.
|
|
|
|
|
*/
|
|
|
|
|
#define KALLSYMS_HIDE(sym) ABSOLUTE(sym)
|
|
|
|
|
|
2015-10-08 22:02:04 +03:00
|
|
|
/*
|
|
|
|
|
* The EFI stub has its own symbol namespace prefixed by __efistub_, to
|
|
|
|
|
* isolate it from the kernel proper. The following symbols are legally
|
|
|
|
|
* accessed by the stub, so provide some aliases to make them accessible.
|
|
|
|
|
* Only include data symbols here, or text symbols of functions that are
|
|
|
|
|
* guaranteed to be safe when executed at another offset than they were
|
|
|
|
|
* linked at. The routines below are all implemented in assembler in a
|
|
|
|
|
* position independent manner
|
|
|
|
|
*/
|
arm64: hide __efistub_ aliases from kallsyms
Commit e8f3010f7326 ("arm64/efi: isolate EFI stub from the kernel
proper") isolated the EFI stub code from the kernel proper by prefixing
all of its symbols with __efistub_, and selectively allowing access to
core kernel symbols from the stub by emitting __efistub_ aliases for
functions and variables that the stub can access legally.
As an unintended side effect, these aliases are emitted into the
kallsyms symbol table, which means they may turn up in backtraces,
e.g.,
...
PC is at __efistub_memset+0x108/0x200
LR is at fixup_init+0x3c/0x48
...
[<ffffff8008328608>] __efistub_memset+0x108/0x200
[<ffffff8008094dcc>] free_initmem+0x2c/0x40
[<ffffff8008645198>] kernel_init+0x20/0xe0
[<ffffff8008085cd0>] ret_from_fork+0x10/0x40
The backtrace in question has nothing to do with the EFI stub, but
simply returns one of the several aliases of memset() that have been
recorded in the kallsyms table. This is undesirable, since it may
suggest to people who are not aware of this that the issue they are
seeing is somehow EFI related.
So hide the __efistub_ aliases from kallsyms, by emitting them as
absolute linker symbols explicitly. The distinction between those
and section relative symbols is completely irrelevant to these
definitions, and to the final link we are performing when these
definitions are being taken into account (the distinction is only
relevant to symbols defined inside a section definition when performing
a partial link), and so the resulting values are identical to the
original ones. Since absolute symbols are ignored by kallsyms, this
will result in these values to be omitted from its symbol table.
After this patch, the backtrace generated from the same address looks
like this:
...
PC is at __memset+0x108/0x200
LR is at fixup_init+0x3c/0x48
...
[<ffffff8008328608>] __memset+0x108/0x200
[<ffffff8008094dcc>] free_initmem+0x2c/0x40
[<ffffff8008645198>] kernel_init+0x20/0xe0
[<ffffff8008085cd0>] ret_from_fork+0x10/0x40
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-01-15 15:28:57 +03:00
|
|
|
__efistub_memcmp = KALLSYMS_HIDE(__pi_memcmp);
|
|
|
|
|
__efistub_memchr = KALLSYMS_HIDE(__pi_memchr);
|
|
|
|
|
__efistub_memcpy = KALLSYMS_HIDE(__pi_memcpy);
|
|
|
|
|
__efistub_memmove = KALLSYMS_HIDE(__pi_memmove);
|
|
|
|
|
__efistub_memset = KALLSYMS_HIDE(__pi_memset);
|
|
|
|
|
__efistub_strlen = KALLSYMS_HIDE(__pi_strlen);
|
|
|
|
|
__efistub_strcmp = KALLSYMS_HIDE(__pi_strcmp);
|
|
|
|
|
__efistub_strncmp = KALLSYMS_HIDE(__pi_strncmp);
|
|
|
|
|
__efistub___flush_dcache_area = KALLSYMS_HIDE(__pi___flush_dcache_area);
|
2015-10-08 22:02:04 +03:00
|
|
|
|
2015-10-12 18:52:58 +03:00
|
|
|
#ifdef CONFIG_KASAN
|
arm64: hide __efistub_ aliases from kallsyms
Commit e8f3010f7326 ("arm64/efi: isolate EFI stub from the kernel
proper") isolated the EFI stub code from the kernel proper by prefixing
all of its symbols with __efistub_, and selectively allowing access to
core kernel symbols from the stub by emitting __efistub_ aliases for
functions and variables that the stub can access legally.
As an unintended side effect, these aliases are emitted into the
kallsyms symbol table, which means they may turn up in backtraces,
e.g.,
...
PC is at __efistub_memset+0x108/0x200
LR is at fixup_init+0x3c/0x48
...
[<ffffff8008328608>] __efistub_memset+0x108/0x200
[<ffffff8008094dcc>] free_initmem+0x2c/0x40
[<ffffff8008645198>] kernel_init+0x20/0xe0
[<ffffff8008085cd0>] ret_from_fork+0x10/0x40
The backtrace in question has nothing to do with the EFI stub, but
simply returns one of the several aliases of memset() that have been
recorded in the kallsyms table. This is undesirable, since it may
suggest to people who are not aware of this that the issue they are
seeing is somehow EFI related.
So hide the __efistub_ aliases from kallsyms, by emitting them as
absolute linker symbols explicitly. The distinction between those
and section relative symbols is completely irrelevant to these
definitions, and to the final link we are performing when these
definitions are being taken into account (the distinction is only
relevant to symbols defined inside a section definition when performing
a partial link), and so the resulting values are identical to the
original ones. Since absolute symbols are ignored by kallsyms, this
will result in these values to be omitted from its symbol table.
After this patch, the backtrace generated from the same address looks
like this:
...
PC is at __memset+0x108/0x200
LR is at fixup_init+0x3c/0x48
...
[<ffffff8008328608>] __memset+0x108/0x200
[<ffffff8008094dcc>] free_initmem+0x2c/0x40
[<ffffff8008645198>] kernel_init+0x20/0xe0
[<ffffff8008085cd0>] ret_from_fork+0x10/0x40
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-01-15 15:28:57 +03:00
|
|
|
__efistub___memcpy = KALLSYMS_HIDE(__pi_memcpy);
|
|
|
|
|
__efistub___memmove = KALLSYMS_HIDE(__pi_memmove);
|
|
|
|
|
__efistub___memset = KALLSYMS_HIDE(__pi_memset);
|
2015-10-12 18:52:58 +03:00
|
|
|
#endif
|
|
|
|
|
|
arm64: hide __efistub_ aliases from kallsyms
Commit e8f3010f7326 ("arm64/efi: isolate EFI stub from the kernel
proper") isolated the EFI stub code from the kernel proper by prefixing
all of its symbols with __efistub_, and selectively allowing access to
core kernel symbols from the stub by emitting __efistub_ aliases for
functions and variables that the stub can access legally.
As an unintended side effect, these aliases are emitted into the
kallsyms symbol table, which means they may turn up in backtraces,
e.g.,
...
PC is at __efistub_memset+0x108/0x200
LR is at fixup_init+0x3c/0x48
...
[<ffffff8008328608>] __efistub_memset+0x108/0x200
[<ffffff8008094dcc>] free_initmem+0x2c/0x40
[<ffffff8008645198>] kernel_init+0x20/0xe0
[<ffffff8008085cd0>] ret_from_fork+0x10/0x40
The backtrace in question has nothing to do with the EFI stub, but
simply returns one of the several aliases of memset() that have been
recorded in the kallsyms table. This is undesirable, since it may
suggest to people who are not aware of this that the issue they are
seeing is somehow EFI related.
So hide the __efistub_ aliases from kallsyms, by emitting them as
absolute linker symbols explicitly. The distinction between those
and section relative symbols is completely irrelevant to these
definitions, and to the final link we are performing when these
definitions are being taken into account (the distinction is only
relevant to symbols defined inside a section definition when performing
a partial link), and so the resulting values are identical to the
original ones. Since absolute symbols are ignored by kallsyms, this
will result in these values to be omitted from its symbol table.
After this patch, the backtrace generated from the same address looks
like this:
...
PC is at __memset+0x108/0x200
LR is at fixup_init+0x3c/0x48
...
[<ffffff8008328608>] __memset+0x108/0x200
[<ffffff8008094dcc>] free_initmem+0x2c/0x40
[<ffffff8008645198>] kernel_init+0x20/0xe0
[<ffffff8008085cd0>] ret_from_fork+0x10/0x40
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-01-15 15:28:57 +03:00
|
|
|
__efistub__text = KALLSYMS_HIDE(_text);
|
|
|
|
|
__efistub__end = KALLSYMS_HIDE(_end);
|
|
|
|
|
__efistub__edata = KALLSYMS_HIDE(_edata);
|
2015-10-08 22:02:04 +03:00
|
|
|
|
|
|
|
|
#endif
|
|
|
|
|
|
arm64: Update the Image header
Currently the kernel Image is stripped of everything past the initial
stack, and at runtime the memory is initialised and used by the kernel.
This makes the effective minimum memory footprint of the kernel larger
than the size of the loaded binary, though bootloaders have no mechanism
to identify how large this minimum memory footprint is. This makes it
difficult to choose safe locations to place both the kernel and other
binaries required at boot (DTB, initrd, etc), such that the kernel won't
clobber said binaries or other reserved memory during initialisation.
Additionally when big endian support was added the image load offset was
overlooked, and is currently of an arbitrary endianness, which makes it
difficult for bootloaders to make use of it. It seems that bootloaders
aren't respecting the image load offset at present anyway, and are
assuming that offset 0x80000 will always be correct.
This patch adds an effective image size to the kernel header which
describes the amount of memory from the start of the kernel Image binary
which the kernel expects to use before detecting memory and handling any
memory reservations. This can be used by bootloaders to choose suitable
locations to load the kernel and/or other binaries such that the kernel
will not clobber any memory unexpectedly. As before, memory reservations
are required to prevent the kernel from clobbering these locations
later.
Both the image load offset and the effective image size are forced to be
little-endian regardless of the native endianness of the kernel to
enable bootloaders to load a kernel of arbitrary endianness. Bootloaders
which wish to make use of the load offset can inspect the effective
image size field for a non-zero value to determine if the offset is of a
known endianness. To enable software to determine the endinanness of the
kernel as may be required for certain use-cases, a new flags field (also
little-endian) is added to the kernel header to export this information.
The documentation is updated to clarify these details. To discourage
future assumptions regarding the value of text_offset, the value at this
point in time is removed from the main flow of the documentation (though
kept as a compatibility note). Some minor formatting issues in the
documentation are also corrected.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Tom Rini <trini@ti.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Kevin Hilman <kevin.hilman@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-06-24 19:51:36 +04:00
|
|
|
#endif /* __ASM_IMAGE_H */
|
