[PATCH v3 8/9] powerpc/kuap: KUAP enabling/disabling functions must be __always_inline

From: Christophe Leroy
Date: Tue Jul 11 2023 - 12:01:10 EST

Objtool reports following warnings:

arch/powerpc/kernel/signal_32.o: warning: objtool:
__prevent_user_access.constprop.0+0x4 (.text+0x4):
redundant UACCESS disable

arch/powerpc/kernel/signal_32.o: warning: objtool: user_access_begin+0x2c
(.text+0x4c): return with UACCESS enabled

arch/powerpc/kernel/signal_32.o: warning: objtool: handle_rt_signal32+0x188
(.text+0x360): call to __prevent_user_access.constprop.0() with UACCESS enabled

arch/powerpc/kernel/signal_32.o: warning: objtool: handle_signal32+0x150
(.text+0x4d4): call to __prevent_user_access.constprop.0() with UACCESS enabled

This is due to some KUAP enabling/disabling functions being outline
allthough they are marked inline. Use __always_inline instead.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
arch/powerpc/include/asm/book3s/32/kup.h | 18 +++++++--------
arch/powerpc/include/asm/book3s/64/kup.h | 23 ++++++++++----------
arch/powerpc/include/asm/kup.h | 16 +++++++-------
arch/powerpc/include/asm/nohash/32/kup-8xx.h | 20 ++++++++---------
arch/powerpc/include/asm/nohash/kup-booke.h | 22 +++++++++----------
arch/powerpc/include/asm/uaccess.h | 6 ++---
6 files changed, 53 insertions(+), 52 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index 452d4efa84f5..931d200afe56 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -15,19 +15,19 @@

#define KUAP_NONE (~0UL)

-static inline void kuap_lock_one(unsigned long addr)
+static __always_inline void kuap_lock_one(unsigned long addr)
{
mtsr(mfsr(addr) | SR_KS, addr);
isync(); /* Context sync required after mtsr() */
}

-static inline void kuap_unlock_one(unsigned long addr)
+static __always_inline void kuap_unlock_one(unsigned long addr)
{
mtsr(mfsr(addr) & ~SR_KS, addr);
isync(); /* Context sync required after mtsr() */
}

-static inline void __kuap_save_and_lock(struct pt_regs *regs)
+static __always_inline void __kuap_save_and_lock(struct pt_regs *regs)
{
unsigned long kuap = current->thread.kuap;

@@ -40,11 +40,11 @@ static inline void __kuap_save_and_lock(struct pt_regs *regs)
}
#define __kuap_save_and_lock __kuap_save_and_lock

-static inline void kuap_user_restore(struct pt_regs *regs)
+static __always_inline void kuap_user_restore(struct pt_regs *regs)
{
}

-static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)
+static __always_inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)
{
if (unlikely(kuap != KUAP_NONE)) {
current->thread.kuap = KUAP_NONE;
@@ -59,7 +59,7 @@ static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kua
kuap_unlock_one(regs->kuap);
}

-static inline unsigned long __kuap_get_and_assert_locked(void)
+static __always_inline unsigned long __kuap_get_and_assert_locked(void)
{
unsigned long kuap = current->thread.kuap;

@@ -94,7 +94,7 @@ static __always_inline void __prevent_user_access(unsigned long dir)
kuap_lock_one(kuap);
}

-static inline unsigned long __prevent_user_access_return(void)
+static __always_inline unsigned long __prevent_user_access_return(void)
{
unsigned long flags = current->thread.kuap;

@@ -106,7 +106,7 @@ static inline unsigned long __prevent_user_access_return(void)
return flags;
}

-static inline void __restore_user_access(unsigned long flags)
+static __always_inline void __restore_user_access(unsigned long flags)
{
if (flags != KUAP_NONE) {
current->thread.kuap = flags;
@@ -114,7 +114,7 @@ static inline void __restore_user_access(unsigned long flags)
}
}

-static inline bool
+static __always_inline bool
__bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
{
unsigned long kuap = regs->kuap;
diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h
index a014f4d9a2aa..497a7bd31ecc 100644
--- a/arch/powerpc/include/asm/book3s/64/kup.h
+++ b/arch/powerpc/include/asm/book3s/64/kup.h
@@ -213,14 +213,14 @@ extern u64 __ro_after_init default_iamr;
* access restrictions. Because of this ignore AMR value when accessing
* userspace via kernel thread.
*/
-static inline u64 current_thread_amr(void)
+static __always_inline u64 current_thread_amr(void)
{
if (current->thread.regs)
return current->thread.regs->amr;
return default_amr;
}

-static inline u64 current_thread_iamr(void)
+static __always_inline u64 current_thread_iamr(void)
{
if (current->thread.regs)
return current->thread.regs->iamr;
@@ -230,7 +230,7 @@ static inline u64 current_thread_iamr(void)

#ifdef CONFIG_PPC_KUAP

-static inline void kuap_user_restore(struct pt_regs *regs)
+static __always_inline void kuap_user_restore(struct pt_regs *regs)
{
bool restore_amr = false, restore_iamr = false;
unsigned long amr, iamr;
@@ -269,7 +269,7 @@ static inline void kuap_user_restore(struct pt_regs *regs)
*/
}

-static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long amr)
+static __always_inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long amr)
{
if (likely(regs->amr == amr))
return;
@@ -285,7 +285,7 @@ static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long amr
*/
}

-static inline unsigned long __kuap_get_and_assert_locked(void)
+static __always_inline unsigned long __kuap_get_and_assert_locked(void)
{
unsigned long amr = mfspr(SPRN_AMR);

@@ -302,7 +302,7 @@ static inline unsigned long __kuap_get_and_assert_locked(void)
* because that would require an expensive read/modify write of the AMR.
*/

-static inline unsigned long get_kuap(void)
+static __always_inline unsigned long get_kuap(void)
{
/*
* We return AMR_KUAP_BLOCKED when we don't support KUAP because
@@ -332,7 +332,8 @@ static __always_inline void set_kuap(unsigned long value)
isync();
}

-static inline bool __bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
+static __always_inline bool
+__bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
{
/*
* For radix this will be a storage protection fault (DSISR_PROTFAULT).
@@ -375,12 +376,12 @@ static __always_inline void allow_user_access(void __user *to, const void __user

#else /* CONFIG_PPC_KUAP */

-static inline unsigned long get_kuap(void)
+static __always_inline unsigned long get_kuap(void)
{
return AMR_KUAP_BLOCKED;
}

-static inline void set_kuap(unsigned long value) { }
+static __always_inline void set_kuap(unsigned long value) { }

static __always_inline void allow_user_access(void __user *to, const void __user *from,
unsigned long size, unsigned long dir)
@@ -395,7 +396,7 @@ static __always_inline void prevent_user_access(unsigned long dir)
do_uaccess_flush();
}

-static inline unsigned long prevent_user_access_return(void)
+static __always_inline unsigned long prevent_user_access_return(void)
{
unsigned long flags = get_kuap();

@@ -406,7 +407,7 @@ static inline unsigned long prevent_user_access_return(void)
return flags;
}

-static inline void restore_user_access(unsigned long flags)
+static __always_inline void restore_user_access(unsigned long flags)
{
set_kuap(flags);
if (static_branch_unlikely(&uaccess_flush_key) && flags == AMR_KUAP_BLOCKED)
diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
index bab161b609c1..77adb9cd2da5 100644
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -57,14 +57,14 @@ static inline void setup_kuap(bool disabled) { }

static __always_inline bool kuap_is_disabled(void) { return true; }

-static inline bool
+static __always_inline bool
__bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
{
return false;
}

-static inline void kuap_user_restore(struct pt_regs *regs) { }
-static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long amr) { }
+static __always_inline void kuap_user_restore(struct pt_regs *regs) { }
+static __always_inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long amr) { }

/*
* book3s/64/kup-radix.h defines these functions for the !KUAP case to flush
@@ -72,11 +72,11 @@ static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long amr
* platforms.
*/
#ifndef CONFIG_PPC_BOOK3S_64
-static inline void __allow_user_access(void __user *to, const void __user *from,
- unsigned long size, unsigned long dir) { }
-static inline void __prevent_user_access(unsigned long dir) { }
-static inline unsigned long __prevent_user_access_return(void) { return 0UL; }
-static inline void __restore_user_access(unsigned long flags) { }
+static __always_inline void __allow_user_access(void __user *to, const void __user *from,
+ unsigned long size, unsigned long dir) { }
+static __always_inline void __prevent_user_access(unsigned long dir) { }
+static __always_inline unsigned long __prevent_user_access_return(void) { return 0UL; }
+static __always_inline void __restore_user_access(unsigned long flags) { }
#endif /* CONFIG_PPC_BOOK3S_64 */
#endif /* CONFIG_PPC_KUAP */

diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
index d0601859c45a..e231b3afed98 100644
--- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
@@ -11,24 +11,24 @@

#include <asm/reg.h>

-static inline void __kuap_save_and_lock(struct pt_regs *regs)
+static __always_inline void __kuap_save_and_lock(struct pt_regs *regs)
{
regs->kuap = mfspr(SPRN_MD_AP);
mtspr(SPRN_MD_AP, MD_APG_KUAP);
}
#define __kuap_save_and_lock __kuap_save_and_lock

-static inline void kuap_user_restore(struct pt_regs *regs)
+static __always_inline void kuap_user_restore(struct pt_regs *regs)
{
}

-static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)
+static __always_inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)
{
mtspr(SPRN_MD_AP, regs->kuap);
}

#ifdef CONFIG_PPC_KUAP_DEBUG
-static inline unsigned long __kuap_get_and_assert_locked(void)
+static __always_inline unsigned long __kuap_get_and_assert_locked(void)
{
WARN_ON_ONCE(mfspr(SPRN_MD_AP) >> 16 != MD_APG_KUAP >> 16);

@@ -37,18 +37,18 @@ static inline unsigned long __kuap_get_and_assert_locked(void)
#define __kuap_get_and_assert_locked __kuap_get_and_assert_locked
#endif

-static inline void __allow_user_access(void __user *to, const void __user *from,
- unsigned long size, unsigned long dir)
+static __always_inline void __allow_user_access(void __user *to, const void __user *from,
+ unsigned long size, unsigned long dir)
{
mtspr(SPRN_MD_AP, MD_APG_INIT);
}

-static inline void __prevent_user_access(unsigned long dir)
+static __always_inline void __prevent_user_access(unsigned long dir)
{
mtspr(SPRN_MD_AP, MD_APG_KUAP);
}

-static inline unsigned long __prevent_user_access_return(void)
+static __always_inline unsigned long __prevent_user_access_return(void)
{
unsigned long flags;

@@ -59,12 +59,12 @@ static inline unsigned long __prevent_user_access_return(void)
return flags;
}

-static inline void __restore_user_access(unsigned long flags)
+static __always_inline void __restore_user_access(unsigned long flags)
{
mtspr(SPRN_MD_AP, flags);
}

-static inline bool
+static __always_inline bool
__bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
{
return !((regs->kuap ^ MD_APG_KUAP) & 0xff000000);
diff --git a/arch/powerpc/include/asm/nohash/kup-booke.h b/arch/powerpc/include/asm/nohash/kup-booke.h
index 8e4734c8fef1..98780a2d3dcd 100644
--- a/arch/powerpc/include/asm/nohash/kup-booke.h
+++ b/arch/powerpc/include/asm/nohash/kup-booke.h
@@ -17,14 +17,14 @@

#include <asm/reg.h>

-static inline void __kuap_lock(void)
+static __always_inline void __kuap_lock(void)
{
mtspr(SPRN_PID, 0);
isync();
}
#define __kuap_lock __kuap_lock

-static inline void __kuap_save_and_lock(struct pt_regs *regs)
+static __always_inline void __kuap_save_and_lock(struct pt_regs *regs)
{
regs->kuap = mfspr(SPRN_PID);
mtspr(SPRN_PID, 0);
@@ -32,7 +32,7 @@ static inline void __kuap_save_and_lock(struct pt_regs *regs)
}
#define __kuap_save_and_lock __kuap_save_and_lock

-static inline void kuap_user_restore(struct pt_regs *regs)
+static __always_inline void kuap_user_restore(struct pt_regs *regs)
{
if (kuap_is_disabled())
return;
@@ -42,7 +42,7 @@ static inline void kuap_user_restore(struct pt_regs *regs)
/* Context synchronisation is performed by rfi */
}

-static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)
+static __always_inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)
{
if (regs->kuap)
mtspr(SPRN_PID, current->thread.pid);
@@ -51,7 +51,7 @@ static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kua
}

#ifdef CONFIG_PPC_KUAP_DEBUG
-static inline unsigned long __kuap_get_and_assert_locked(void)
+static __always_inline unsigned long __kuap_get_and_assert_locked(void)
{
WARN_ON_ONCE(mfspr(SPRN_PID));

@@ -60,20 +60,20 @@ static inline unsigned long __kuap_get_and_assert_locked(void)
#define __kuap_get_and_assert_locked __kuap_get_and_assert_locked
#endif

-static inline void __allow_user_access(void __user *to, const void __user *from,
- unsigned long size, unsigned long dir)
+static __always_inline void __allow_user_access(void __user *to, const void __user *from,
+ unsigned long size, unsigned long dir)
{
mtspr(SPRN_PID, current->thread.pid);
isync();
}

-static inline void __prevent_user_access(unsigned long dir)
+static __always_inline void __prevent_user_access(unsigned long dir)
{
mtspr(SPRN_PID, 0);
isync();
}

-static inline unsigned long __prevent_user_access_return(void)
+static __always_inline unsigned long __prevent_user_access_return(void)
{
unsigned long flags = mfspr(SPRN_PID);

@@ -83,7 +83,7 @@ static inline unsigned long __prevent_user_access_return(void)
return flags;
}

-static inline void __restore_user_access(unsigned long flags)
+static __always_inline void __restore_user_access(unsigned long flags)
{
if (flags) {
mtspr(SPRN_PID, current->thread.pid);
@@ -91,7 +91,7 @@ static inline void __restore_user_access(unsigned long flags)
}
}

-static inline bool
+static __always_inline bool
__bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
{
return !regs->kuap;
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index a2d255aa9627..fb725ec77926 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -386,7 +386,7 @@ copy_mc_to_user(void __user *to, const void *from, unsigned long n)
extern long __copy_from_user_flushcache(void *dst, const void __user *src,
unsigned size);

-static __must_check inline bool user_access_begin(const void __user *ptr, size_t len)
+static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len)
{
if (unlikely(!access_ok(ptr, len)))
return false;
@@ -401,7 +401,7 @@ static __must_check inline bool user_access_begin(const void __user *ptr, size_t
#define user_access_save prevent_user_access_return
#define user_access_restore restore_user_access

-static __must_check inline bool
+static __must_check __always_inline bool
user_read_access_begin(const void __user *ptr, size_t len)
{
if (unlikely(!access_ok(ptr, len)))
@@ -415,7 +415,7 @@ user_read_access_begin(const void __user *ptr, size_t len)
#define user_read_access_begin user_read_access_begin
#define user_read_access_end prevent_current_read_from_user

-static __must_check inline bool
+static __must_check __always_inline bool
user_write_access_begin(const void __user *ptr, size_t len)
{
if (unlikely(!access_ok(ptr, len)))
--
2.41.0