On 03/13/2018 01:41 PM, Christian Borntraeger wrote:
> Gerd,
>
> another thing with virtio-gpu.
>
> I can successfully do suspend/resume (echo disk > /sys/power/state) on my
> system. As soon as I have a
> virtio-gpu the system hangs on reboot/shutdown:
>
> e.g.
>
> crash> bt 1
> PID: 1
Also add David and dri list.
Short summary, suspend/resume breaks with virtio-gpu as there are no
freeze/restore callbacks
that put the device back into working state.
On 03/13/2018 02:32 PM, Christian Borntraeger wrote:
>
>
> On 03/13/2018 01:41 PM, Christian Borntraeger wrote:
>> Gerd,
if PIE is enabled, switch the paravirt assembly constraints to be
compatible. The %c/i constrains generate smaller code so is kept by
default.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas
Perpcu uses a clever design where the .percu ELF section has a virtual
address of zero and the relocation code avoid relocating specific
symbols. It makes the code simple and easily adaptable with or without
SMP support.
This design is incompatible with PIE because generated code always try to
The __startup_64 function assumes all symbols have relocated addresses
instead of the current boot virtual address. PIE generated code favor
relative addresses making all virtual and physical address math incorrect.
If PIE is enabled, build head64.c as mcmodel large instead to ensure absolute
Provide an option to default visibility to hidden except for key
symbols. This option is disabled by default and will be used by x86_64
PIE support to remove errors between compilation units.
The default visibility is also enabled for external symbols that are
compared as they maybe equals
Provide an option to have a PROVIDE_HIDDEN (linker script) entry for
each weak symbol. This option solve an error in x86_64 where the linker
optimizes pie generate code to be non-pie because --emit-relocs was used
instead of -pie (to reduce dynamic relocations).
Signed-off-by: Thomas Garnier
Change the relocation tool to correctly handle relocations generated by
-fPIE option:
- Add relocation for each entry of the .got section given the linker does not
generate R_X86_64_GLOB_DAT on a simple link.
- Ignore R_X86_64_GOTPCREL.
Signed-off-by: Thomas Garnier
Add an option so the module section is just after the mapped kernel. It
will ensure position independent modules are always at the right
distance from the kernel and do not require mcmodule=large. It also
optimize the available size for modules by getting rid of the empty
space on kernel
Adapt module loading to support PIE relocations. Generate dynamic GOT if
a symbol requires it but no entry exist in the kernel GOT.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas Garnier
Add an off-by-default configuration option to use a global stack cookie
instead of the default TLS. This configuration option will only be used
with PIE binaries.
For kernel stack cookie, the compiler uses the mcmodel=kernel to switch
between the fs segment to gs segment. A PIE binary does not
Change the assembly code to use the new _ASM_MOVABS macro which get a
symbol reference while being PIE compatible. Adapt the relocation tool
to ignore 32-bit Xen code.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible. The new __ASM_MOVABS macro is used to
get the address of a symbol on both 32 and 64-bit with PIE support.
Position Independent Executable (PIE) support will allow to extended the
KASLR
When using -fPIE/PIC with function tracing, the compiler generates a
call through the GOT (call *__fentry__@GOTPCREL). This instruction
takes 6 bytes instead of 5 on the usual relative call.
If PIE is enabled, replace the 6th byte of the GOT call by a 1-byte nop
so ftrace can handle the previous
The GOT is changed during early boot when relocations are applied. Make
it read-only directly. This table exists only for PIE binary.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas Garnier
The x86 relocation tool generates a list of 32-bit signed integers. There
was no need to use 64-bit integers because all addresses where above the 2G
top of the memory.
This change add a large-reloc option to generate 64-bit unsigned integers.
It can be used when the kernel plan to go below the
Changes:
- patch v2:
- Adapt patch to work post KPTI and compiler changes
- Redo all performance testing with latest configs and compilers
- Simplify mov macro on PIE (MOVABS now)
- Reduce GOT footprint
- patch v1:
- Simplify ftrace implementation.
- Use gcc
Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas Garnier
---
Replace the %c constraint with %P. The %c is incompatible with PIE
because it implies an immediate value whereas %P reference a symbol.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas Garnier
Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas Garnier
---
Replace the %c constraint with %P. The %c is incompatible with PIE
because it implies an immediate value whereas %P reference a symbol.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas Garnier
Add a new _ASM_MOVABS macro to fetch a symbol address. It will be used
to replace "_ASM_MOV $, %dst" code construct that are not compatible
with PIE.
Signed-off-by: Thomas Garnier
---
arch/x86/include/asm/asm.h | 1 +
1 file changed, 1 insertion(+)
diff --git
Change assembly to use the new _ASM_MOVABS macro instead of _ASM_MOV for
the assembly to be PIE compatible.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas Garnier
---
Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas Garnier
---
Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible. Use the new _ASM_MOVABS macro instead of
the 'mov $symbol, %dst' construct.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G
Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas Garnier
---
Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas Garnier
---
Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.
Early at boot, the kernel is mapped at a temporary address while preparing
the page table. To know the changes needed for the page table with KASLR,
the boot code calculate the difference
Add the CONFIG_X86_PIE option which builds the kernel as a Position
Independent Executable (PIE). The kernel is currently build with the
mcmodel=kernel option which forces it to stay on the top 2G of the
virtual address space. With PIE, the kernel will be able to move below
the current limit.
The
Add a new CONFIG_RANDOMIZE_BASE_LARGE option to benefit from PIE
support. It increases the KASLR range from 1GB to 3GB. The new range
stars at 0x just above the EFI memory region. This
option is off by default.
The boot code is adapted to create the appropriate page table spanning
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