kernel/linux.git/arch/powerpc/include/asm/thread_info.h, branch linux-6.12.y

powerpc/32: Implement validation of emergency stack

2024-08-30T11:30:20+00:00

VMAP stack added an emergency stack on powerpc/32 for when there is a stack overflow, but failed to add stack validation for that emergency stack. That validation is required for show stack. Implement it. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://msgid.link/2439d50b019f758db4a6d7b238b06441ab109799.1724156805.git.christophe.leroy@csgroup.eu

powerpc/kasan: Limit KASAN thread size increase to 32KB

2024-02-14T03:24:06+00:00

KASAN is seen to increase stack usage, to the point that it was reported to lead to stack overflow on some 32-bit machines (see link). To avoid overflows the stack size was doubled for KASAN builds in commit 3e8635fb2e07 ("powerpc/kasan: Force thread size increase with KASAN"). However with a 32KB stack size to begin with, the doubling leads to a 64KB stack, which causes build errors: arch/powerpc/kernel/switch.S:249: Error: operand out of range (0x000000000000fe50 is not between 0xffffffffffff8000 and 0x0000000000007fff) Although the asm could be reworked, in practice a 32KB stack seems sufficient even for KASAN builds - the additional usage seems to be in the 2-3KB range for a 64-bit KASAN build. So only increase the stack for KASAN if the stack size is < 32KB. Fixes: 18f14afe2816 ("powerpc/64s: Increase default stack size to 32KB") Reported-by: Spoorthy Reported-by: Benjamin Gray Reviewed-by: Benjamin Gray Link: https://lore.kernel.org/linuxppc-dev/bug-207129-206035@https.bugzilla.kernel.org%2F/ Signed-off-by: Michael Ellerman Link: https://msgid.link/20240212064244.3924505-1-mpe@ellerman.id.au

Revert "powerpc/64s: Remove support for ELFv1 little endian userspace"

2023-07-19T11:28:35+00:00

This reverts commit 606787fed7268feb256957872586370b56af697a. ELFv1 with LE has never been a thing, and people who try to make ELFv1 LE binaries are maniacs who need to be stopped, but unfortunately there are ELFv1 LE binaries out there in the wild. One such binary is the ppc64el (as Debian calls it) helper for arch-test[0], a tool for detecting architectures that can be executed on a given machine by means of attempting to execute helper binaries compiled for each architecture and seeing which binaries succeed and fail. The helpers are small snippets of assembly, and the ppc64el assembly doesn't include the right directives to generate an ELFv2 binary. This results in arch-test incorrectly determining that a ppc64el kernel can't execute a ppc64el userspace, which in turn means that a number of developer tools such as debootstrap will break (assuming arch-test is installed). [0] https://github.com/kilobyte/arch-test Signed-off-by: Andrew Donnellan Signed-off-by: Michael Ellerman Link: https://msgid.link/20230719071821.320594-1-ajd@linux.ibm.com

powerpc/64s: Remove support for ELFv1 little endian userspace

2023-06-14T02:46:42+00:00

ELFv2 was introduced together with little-endian. ELFv1 with LE has never been a thing. The GNU toolchain can create such a beast, but anyone doing that is a maniac who needs to be stopped so I consider this patch a feature. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://msgid.link/20230606093832.199712-5-npiggin@gmail.com

powerpc: copy_thread differentiate kthreads and user mode threads

2023-04-11T13:13:33+00:00

When copy_thread is given a kernel function to run in arg->fn, this does not necessarily mean it is a kernel thread. User threads can be created this way (e.g., kernel_init, see also x86's copy_thread()). These threads run a kernel function which may call kernel_execve() and return, which returns like a userspace exec(2) syscall. Kernel threads are to be differentiated with PF_KTHREAD, will always have arg->fn set, and should never return from that function, instead calling kthread_exit() to exit. Create separate paths for the kthread and user kernel thread creation logic. The kthread path will never exit and does not require a user interrupt frame, so it gets a minimal stack frame. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://msgid.link/20230325122904.2375060-6-npiggin@gmail.com

powerpc: Implement arch_within_stack_frames

2023-04-04T12:11:03+00:00

Walks the stack when copy_{to,from}_user address is in the stack to ensure that the object being copied is entirely a single stack frame and does not contain stack metadata. Substantially similar to the x86 implementation. The back chain is used to traverse the stack and identify stack frame boundaries. Signed-off-by: Nicholas Miehlbradt Signed-off-by: Michael Ellerman Link: https://msgid.link/20230228054355.300628-1-nicholas@linux.ibm.com

powerpc/kasan: Force thread size increase with KASAN

2022-06-02T12:56:47+00:00

KASAN causes increased stack usage, which can lead to stack overflows. The logic in Kconfig to suggest a larger default doesn't work if a user has CONFIG_EXPERT enabled and has an existing .config with a smaller value. Follow the lead of x86 and arm64, and force the thread size to be increased when KASAN is enabled. That also has the effect of enlarging the stack for 64-bit KASAN builds, which is also desirable. Fixes: edbadaf06710 ("powerpc/kasan: Fix stack overflow by increasing THREAD_SHIFT") Reported-by: Erhard Furtner Reported-by: Christophe Leroy [mpe: Use MIN_THREAD_SHIFT as suggested by Christophe] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220601143114.133524-1-mpe@ellerman.id.au

powerpc/ftrace: Add support for livepatch to PPC32

2022-02-07T10:03:10+00:00

PPC64 needs some special logic to properly set up the TOC. See commit 85baa095497f ("powerpc/livepatch: Add live patching support on ppc64le") for details. PPC32 doesn't have TOC so it doesn't need that logic, so adding LIVEPATCH support is straight forward. Add CONFIG_LIVEPATCH_64 and move livepatch stack logic into that item. Livepatch sample modules all work. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/63cb094125b6a6038c65eeac2abaabbabe63addd.1640017960.git.christophe.leroy@csgroup.eu

powerpc/audit: Fix syscall_get_arch()

2022-01-15T01:21:26+00:00

Commit 770cec16cdc9 ("powerpc/audit: Simplify syscall_get_arch()") and commit 898a1ef06ad4 ("powerpc/audit: Avoid unneccessary #ifdef in syscall_get_arguments()") replaced test_tsk_thread_flag(task, TIF_32BIT)) by is_32bit_task(). But is_32bit_task() applies on current task while be want the test done on task 'task' So add a new macro is_tsk_32bit_task() to check any task. Fixes: 770cec16cdc9 ("powerpc/audit: Simplify syscall_get_arch()") Fixes: 898a1ef06ad4 ("powerpc/audit: Avoid unneccessary #ifdef in syscall_get_arguments()") Cc: stable@vger.kernel.org Reported-by: Dmitry V. Levin Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/c55cddb8f65713bf5859ed675d75a50cb37d5995.1642159570.git.christophe.leroy@csgroup.eu

powerpc: add CPU field to struct thread_info

2021-09-30T14:13:10+00:00

The CPU field will be moved back into thread_info even when THREAD_INFO_IN_TASK is enabled, so add it back to powerpc's definition of struct thread_info. Signed-off-by: Ard Biesheuvel Acked-by: Mark Rutland Acked-by: Michael Ellerman