linux.git/arch/um/os-Linux/main.c, branch for-next Linux kernel source tree um: remove PATH_MAX use 2024-10-24T07:52:51+00:00 Johannes Berg johannes.berg@intel.com 2024-10-24T07:52:51+00:00 d61ac4a7496a7981947b8b894d40b0e35c316fa5 Evidently, PATH_MAX isn't always defined, at least not via <limits.h>. Simply remove the use and replace it by a constant 4k. As stat::st_size is zero for /proc/self/exe we can't even size it automatically, and it seems unlikely someone's going to try to run UML with such a path. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202410240553.gYNIXN8i-lkp@intel.com/ Fixes: 031acdcfb566 ("um: restore process name") Signed-off-by: Johannes Berg <johannes.berg@intel.com> 
Evidently, PATH_MAX isn't always defined, at least not via <limits.h>.
Simply remove the use and replace it by a constant 4k. As stat::st_size
is zero for /proc/self/exe we can't even size it automatically, and it
seems unlikely someone's going to try to run UML with such a path.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202410240553.gYNIXN8i-lkp@intel.com/
Fixes: 031acdcfb566 ("um: restore process name")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
um: restore process name 2024-10-23T07:25:55+00:00 Johannes Berg johannes.berg@intel.com 2024-10-10T14:14:12+00:00 031acdcfb566ba18ffb57d51abf357a5e350424b After the execve() to disable ASLR, comm is now "exe", which is a bit confusing. Use readlink() to get this to the right name again. Disable stack frame size warnings on main.o since it's part of the initial userspace and can use larger stack. Fixes: 68b9883cc16e ("um: Discover host_task_size from envp") Link: https://patch.msgid.link/20241010161411.c576e2aeb3e5.I244d4f34b8a8555ee5bec0e1cf5027bce4cc491b@changeid Signed-off-by: Johannes Berg <johannes.berg@intel.com> 
After the execve() to disable ASLR, comm is now "exe",
which is a bit confusing. Use readlink() to get this
to the right name again.

Disable stack frame size warnings on main.o since it's
part of the initial userspace and can use larger stack.

Fixes: 68b9883cc16e ("um: Discover host_task_size from envp")
Link: https://patch.msgid.link/20241010161411.c576e2aeb3e5.I244d4f34b8a8555ee5bec0e1cf5027bce4cc491b@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
um: Discover host_task_size from envp 2024-10-10T11:37:22+00:00 Benjamin Berg benjamin.berg@intel.com 2024-09-19T12:45:09+00:00 68b9883cc16ec2ce699d832ef60241b1a4e47d33 When loading the UML binary, the host kernel will place the stack at the highest possible address. It will then map the program name and environment variables onto the start of the stack. As such, an easy way to figure out the host_task_size is to use the highest pointer to an environment variable as a reference. Ensure that this works by disabling address layout randomization and re-executing UML in case it was enabled. This increases the available TASK_SIZE for 64 bit UML considerably. Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20240919124511.282088-9-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com> 
When loading the UML binary, the host kernel will place the stack at the
highest possible address. It will then map the program name and
environment variables onto the start of the stack.

As such, an easy way to figure out the host_task_size is to use the
highest pointer to an environment variable as a reference.

Ensure that this works by disabling address layout randomization and
re-executing UML in case it was enabled.

This increases the available TASK_SIZE for 64 bit UML considerably.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240919124511.282088-9-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
um: Remove the redundant declaration of high_physmem 2024-10-10T10:02:12+00:00 Tiwei Bie tiwei.btw@antgroup.com 2024-09-16T04:59:47+00:00 855f6e18dff26fb13968a73998b0d0ff38865b51 high_physmem has already been declared in as-layout.h, so there is no need to declare it explicitly in the .c file again. While at it, group the declarations of __real_malloc and __real_free together to make the code slightly more readable. Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Link: https://patch.msgid.link/20240916045950.508910-2-tiwei.btw@antgroup.com Signed-off-by: Johannes Berg <johannes.berg@intel.com> 
high_physmem has already been declared in as-layout.h, so there is
no need to declare it explicitly in the .c file again.

While at it, group the declarations of __real_malloc and __real_free
together to make the code slightly more readable.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20240916045950.508910-2-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
um: Add an internal header shared among the user code 2024-04-30T12:16:44+00:00 Tiwei Bie tiwei.btw@antgroup.com 2024-04-23T12:58:56+00:00 847d3abc6aeda1266192d4236e6a766cdf04eb0f Move relevant declarations to this header. This will address below -Wmissing-prototypes warnings: arch/um/os-Linux/elf_aux.c:26:13: warning: no previous prototype for ‘scan_elf_aux’ [-Wmissing-prototypes] arch/um/os-Linux/mem.c:213:13: warning: no previous prototype for ‘check_tmpexec’ [-Wmissing-prototypes] arch/um/os-Linux/skas/process.c:107:6: warning: no previous prototype for ‘wait_stub_done’ [-Wmissing-prototypes] Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Signed-off-by: Richard Weinberger <richard@nod.at> 
Move relevant declarations to this header. This will address
below -Wmissing-prototypes warnings:

arch/um/os-Linux/elf_aux.c:26:13: warning: no previous prototype for ‘scan_elf_aux’ [-Wmissing-prototypes]
arch/um/os-Linux/mem.c:213:13: warning: no previous prototype for ‘check_tmpexec’ [-Wmissing-prototypes]
arch/um/os-Linux/skas/process.c:107:6: warning: no previous prototype for ‘wait_stub_done’ [-Wmissing-prototypes]

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
um: Fix -Wmissing-prototypes warnings for __warp_* and foo 2024-04-22T19:58:48+00:00 Tiwei Bie tiwei.btw@antgroup.com 2024-03-06T10:19:25+00:00 49ff7d871242d7fd8adb8a2d8347c5d94dda808b These functions are not called explicitly. Let's just workaround the -Wmissing-prototypes warnings by declaring them locally similar to what was done in arch/x86/kernel/asm-offsets_32.c. This will address below -Wmissing-prototypes warnings: ./arch/x86/um/shared/sysdep/kernel-offsets.h:9:6: warning: no previous prototype for ‘foo’ [-Wmissing-prototypes] arch/um/os-Linux/main.c:187:7: warning: no previous prototype for ‘__wrap_malloc’ [-Wmissing-prototypes] arch/um/os-Linux/main.c:208:7: warning: no previous prototype for ‘__wrap_calloc’ [-Wmissing-prototypes] arch/um/os-Linux/main.c:222:6: warning: no previous prototype for ‘__wrap_free’ [-Wmissing-prototypes] arch/x86/um/user-offsets.c:17:6: warning: no previous prototype for ‘foo’ [-Wmissing-prototypes] Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Signed-off-by: Richard Weinberger <richard@nod.at> 
These functions are not called explicitly. Let's just workaround
the -Wmissing-prototypes warnings by declaring them locally similar
to what was done in arch/x86/kernel/asm-offsets_32.c.

This will address below -Wmissing-prototypes warnings:

./arch/x86/um/shared/sysdep/kernel-offsets.h:9:6: warning: no previous prototype for ‘foo’ [-Wmissing-prototypes]
arch/um/os-Linux/main.c:187:7: warning: no previous prototype for ‘__wrap_malloc’ [-Wmissing-prototypes]
arch/um/os-Linux/main.c:208:7: warning: no previous prototype for ‘__wrap_calloc’ [-Wmissing-prototypes]
arch/um/os-Linux/main.c:222:6: warning: no previous prototype for ‘__wrap_free’ [-Wmissing-prototypes]
arch/x86/um/user-offsets.c:17:6: warning: no previous prototype for ‘foo’ [-Wmissing-prototypes]

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
um: Don't trace irqflags during shutdown 2019-11-25T21:42:57+00:00 Johannes Berg johannes.berg@intel.com 2019-09-17T11:20:14+00:00 5c1f33e2a03c0b8710b5d910a46f1e1fb0607679 In the main() code, we eventually enable signals just before exec() or exit(), in order to to not have signals pending and delivered *after* the exec(). I've observed SIGSEGV loops at this point, and the reason seems to be the irqflags tracing; this makes sense as the kernel is no longer really functional at this point. Since there's really no reason to use unblock_signals_trace() here (I had just done a global search & replace), use the plain unblock_signals() in this case to avoid going into the no longer functional kernel. Fixes: 0dafcbe128d2 ("um: Implement TRACE_IRQFLAGS_SUPPORT") Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Richard Weinberger <richard@nod.at> 
In the main() code, we eventually enable signals just before
exec() or exit(), in order to to not have signals pending and
delivered *after* the exec().

I've observed SIGSEGV loops at this point, and the reason seems
to be the irqflags tracing; this makes sense as the kernel is
no longer really functional at this point. Since there's really
no reason to use unblock_signals_trace() here (I had just done
a global search & replace), use the plain unblock_signals() in
this case to avoid going into the no longer functional kernel.

Fixes: 0dafcbe128d2 ("um: Implement TRACE_IRQFLAGS_SUPPORT")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
um: Add SPDX headers for files in arch/um/os-Linux 2019-09-15T19:37:17+00:00 Alex Dewar alex.dewar@gmx.co.uk 2019-08-25T09:49:18+00:00 97870c34b453251cda9c2341f8534b78003a74dc Convert files to use SPDX header. All files are licensed under the GPLv2. Signed-off-by: Alex Dewar <alex.dewar@gmx.co.uk> Signed-off-by: Richard Weinberger <richard@nod.at> 
Convert files to use SPDX header. All files are licensed under the GPLv2.

Signed-off-by: Alex Dewar <alex.dewar@gmx.co.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
um: Implement TRACE_IRQFLAGS_SUPPORT 2019-09-15T19:37:11+00:00 Johannes Berg johannes.berg@intel.com 2019-08-23T11:16:23+00:00 0dafcbe128d2af48919619f79332ef219b5e5514 UML enables TRACE_IRQFLAGS_SUPPORT but doesn't actually implement it. It seems to have been added for lockdep support, but that can't actually really work well without IRQ flags tracing, as is also very noisily reported when enabling CONFIG_DEBUG_LOCKDEP. Implement it now. Fixes: 711553efa5b8 ("[PATCH] uml: declare in Kconfig our partial LOCKDEP support") Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Richard Weinberger <richard@nod.at> 
UML enables TRACE_IRQFLAGS_SUPPORT but doesn't actually implement
it. It seems to have been added for lockdep support, but that can't
actually really work well without IRQ flags tracing, as is also
very noisily reported when enabling CONFIG_DEBUG_LOCKDEP.

Implement it now.

Fixes: 711553efa5b8 ("[PATCH] uml: declare in Kconfig our partial LOCKDEP support")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
um: remove uml initcalls 2018-06-10T20:49:14+00:00 Alexander Pateenok pateenoc@gmail.com 2018-04-23T18:20:17+00:00 cca76c1ad61d08097af5a691195f9a42d72e978f __uml_initcall() is not used and .uml.initcall.init section is empty: $ grep -r '__uml_initcall(' arch/um/include/shared/init.h:#define __uml_initcall(fn) \ $ readelf -s ../umobj/linux | grep __uml_initcall 23214: 00000000603b75d8 0 NOTYPE GLOBAL DEFAULT 32 __uml_initcall_start 25337: 00000000603b75d8 0 NOTYPE GLOBAL DEFAULT 32 __uml_initcall_end So it is unnecessary. Signed-off-by: Alexander Pateenok <pateenoc@gmail.com> Signed-off-by: Richard Weinberger <richard@nod.at> 
__uml_initcall() is not used and .uml.initcall.init section is empty:

$ grep -r '__uml_initcall('
arch/um/include/shared/init.h:#define __uml_initcall(fn)	\
$ readelf -s ../umobj/linux | grep __uml_initcall
 23214: 00000000603b75d8     0 NOTYPE  GLOBAL DEFAULT   32 __uml_initcall_start
 25337: 00000000603b75d8     0 NOTYPE  GLOBAL DEFAULT   32 __uml_initcall_end

So it is unnecessary.

Signed-off-by: Alexander Pateenok <pateenoc@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>