treewide: context_tracking: Rename CONTEXT_* into CT_STATE_*

Context tracking state related symbols currently use a mix of the
CONTEXT_ (e.g. CONTEXT_KERNEL) and CT_SATE_ (e.g. CT_STATE_MASK) prefix

treewide: context_tracking: Rename CONTEXT_* into CT_STATE_*

Context tracking state related symbols currently use a mix of the
CONTEXT_ (e.g. CONTEXT_KERNEL) and CT_SATE_ (e.g. CT_STATE_MASK) prefixes.

Clean up the naming and make the ctx_state enum use the CT_STATE_ prefix.

Suggested-by: Frederic Weisbecker <[email protected]>
Signed-off-by: Valentin Schneider <[email protected]>
Acked-by: Frederic Weisbecker <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
Signed-off-by: Neeraj Upadhyay <[email protected]>

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powerpc: Use user_mode() macro when possible

There is a nice macro to check user mode.

Use it instead of open coding anding with MSR_PR to increase
readability and avoid having to comment what that

powerpc: Use user_mode() macro when possible

There is a nice macro to check user mode.

Use it instead of open coding anding with MSR_PR to increase
readability and avoid having to comment what that anding is for.

Signed-off-by: Christophe Leroy <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://msgid.link/fbf74887dcf1f1ba9e1680fc3247cbb581b00662.1708078228.git.christophe.leroy@csgroup.eu

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powerpc/kuap: MMU_FTR_BOOK3S_KUAP becomes MMU_FTR_KUAP

In order to reuse MMU_FTR_BOOK3S_KUAP for other targets than BOOK3S,
rename it MMU_FTR_KUAP.

Signed-off-by: Christophe Leroy <christophe.leroy

powerpc/kuap: MMU_FTR_BOOK3S_KUAP becomes MMU_FTR_KUAP

In order to reuse MMU_FTR_BOOK3S_KUAP for other targets than BOOK3S,
rename it MMU_FTR_KUAP.

Signed-off-by: Christophe Leroy <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://msgid.link/c8b6f7b8cd0eeaace96879ed0e0a157faa619451.1689091022.git.christophe.leroy@csgroup.eu

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powerpc: Provide syscall wrapper

Implement syscall wrapper as per s390, x86, arm64. When enabled
cause handlers to accept parameters from a stack frame rather than
from user scratch register state.

powerpc: Provide syscall wrapper

Implement syscall wrapper as per s390, x86, arm64. When enabled
cause handlers to accept parameters from a stack frame rather than
from user scratch register state. This allows for user registers to be
safely cleared in order to reduce caller influence on speculation
within syscall routine. The wrapper is a macro that emits syscall
handler symbols that call into the target handler, obtaining its
parameters from a struct pt_regs on the stack.

As registers are already saved to the stack prior to calling
system_call_exception, it appears that this function is executed more
efficiently with the new stack-pointer convention than with parameters
passed by registers, avoiding the allocation of a stack frame for this
method. On a 32-bit system, we see >20% performance increases on the
null_syscall microbenchmark, and on a Power 8 the performance gains
amortise the cost of clearing and restoring registers which is
implemented at the end of this series, seeing final result of ~5.6%
performance improvement on null_syscall.

Syscalls are wrapped in this fashion on all platforms except for the
Cell processor as this commit does not provide SPU support. This can be
quickly fixed in a successive patch, but requires spu_sys_callback to
allocate a pt_regs structure to satisfy the wrapped calling convention.

Co-developed-by: Andrew Donnellan <[email protected]>
Signed-off-by: Andrew Donnellan <[email protected]>
Signed-off-by: Rohan McLure <[email protected]>
Reviewed-by: Nicholas Piggin <[email protected]>
[mpe: Make incompatible with COMPAT to retain clearing of high bits of args]
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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powerpc: Change system_call_exception calling convention

Change system_call_exception arguments to pass a pointer to a stack
frame container caller state, as well as the original r0, which
determine

powerpc: Change system_call_exception calling convention

Change system_call_exception arguments to pass a pointer to a stack
frame container caller state, as well as the original r0, which
determines the number of the syscall. This has been observed to yield
improved performance to passing them by registers, circumventing the
need to allocate a stack frame.

Signed-off-by: Rohan McLure <[email protected]>
Reviewed-by: Nicholas Piggin <[email protected]>
[mpe: Retain clearing of high bits of args for compat tasks]
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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powerpc: Use common syscall handler type

Cause syscall handlers to be typed as follows when called indirectly
throughout the kernel. This is to allow for better type checking.

typedef long (*syscal

powerpc: Use common syscall handler type

Cause syscall handlers to be typed as follows when called indirectly
throughout the kernel. This is to allow for better type checking.

typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long,
unsigned long, unsigned long, unsigned long);

Since both 32 and 64-bit abis allow for at least the first six
machine-word length parameters to a function to be passed by registers,
even handlers which admit fewer than six parameters may be viewed as
having the above type.

Coercing syscalls to syscall_fn requires a cast to void* to avoid
-Wcast-function-type.

Fixup comparisons in VDSO to avoid pointer-integer comparison. Introduce
explicit cast on systems with SPUs.

Signed-off-by: Rohan McLure <[email protected]>
Reviewed-by: Nicholas Piggin <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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powerpc: Save caller r3 prior to system_call_exception

This reverts commit 8875f47b7681 ("powerpc/syscall: Save r3 in regs->orig_r3
").

Save caller's original r3 state to the kernel stackframe befo

powerpc: Save caller r3 prior to system_call_exception

This reverts commit 8875f47b7681 ("powerpc/syscall: Save r3 in regs->orig_r3
").

Save caller's original r3 state to the kernel stackframe before entering
system_call_exception. This allows for user registers to be cleared by
the time system_call_exception is entered, reducing the influence of
user registers on speculation within the kernel.

Prior to this commit, orig_r3 was saved at the beginning of
system_call_exception. Instead, save orig_r3 while the user value is
still live in r3.

Also replicate this early save in 32-bit. A similar save was removed in
commit 6f76a01173cc ("powerpc/syscall: implement system call entry/exit
logic in C for PPC32") when 32-bit adopted system_call_exception. Revert
its removal of orig_r3 saves.

Signed-off-by: Rohan McLure <[email protected]>
Reviewed-by: Nicholas Piggin <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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powerpc: add support for syscall stack randomization

Add support for adding a random offset to the stack while handling
syscalls. This patch uses mftb() instead of get_random_int() for better
perfor

powerpc: add support for syscall stack randomization

Add support for adding a random offset to the stack while handling
syscalls. This patch uses mftb() instead of get_random_int() for better
performance.

In order to avoid unconditional stack canaries on syscall entry (due to
the use of alloca()), also disable stack protector to avoid triggering
needless checks and slowing down the entry path. As there is no general
way to control stack protector coverage with a function attribute, this
must be disabled at the compilation unit level.

Signed-off-by: Xiu Jianfeng <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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powerpc: Move system_call_exception() to syscall.c

This is a lead-up patch to enable syscall stack randomization, which
uses alloca() and makes the compiler add unconditional stack canaries
on sysca

powerpc: Move system_call_exception() to syscall.c

This is a lead-up patch to enable syscall stack randomization, which
uses alloca() and makes the compiler add unconditional stack canaries
on syscall entry. In order to avoid triggering needless checks and
slowing down the entry path, the feature needs to disable stack
protector at the compilation unit level as there is no general way to
control stack protector coverage with a function attribute.

So move system_call_exception() to syscall.c to avoid affecting other
functions in interrupt.c.

Suggested-by: Michael Ellerman <[email protected]>
Signed-off-by: Xiu Jianfeng <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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