[PATCH v3 05/15] powerpc/kuap: KUAP enabling/disabling functions must be __always_inline

From: Christophe Leroy
Date: Fri Jun 23 2023 - 13:09:24 EST

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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 | 26 ++++++++++----------
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, 57 insertions(+), 56 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index 8da9997a67ba..41746a22c650 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -23,25 +23,25 @@ static __always_inline bool kuep_is_disabled(void)
#define KUAP_NONE (~0UL)
#define KUAP_ALL (~1UL)

-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_lock_all(void)
+static __always_inline void kuap_lock_all(void)
{
update_user_segments(mfsr(0) | SR_KS);
isync(); /* Context sync required after mtsr() */
}

-static inline void kuap_unlock_all(void)
+static __always_inline void kuap_unlock_all(void)
{
update_user_segments(mfsr(0) & ~SR_KS);
isync(); /* Context sync required after mtsr() */
@@ -50,7 +50,7 @@ static inline void kuap_unlock_all(void)
void kuap_lock_all_ool(void);
void kuap_unlock_all_ool(void);

-static inline void kuap_lock_addr(unsigned long addr, bool ool)
+static __always_inline void kuap_lock_addr(unsigned long addr, bool ool)
{
if (likely(addr != KUAP_ALL))
kuap_lock_one(addr);
@@ -60,7 +60,7 @@ static inline void kuap_lock_addr(unsigned long addr, bool ool)
kuap_lock_all_ool();
}

-static inline void kuap_unlock(unsigned long addr, bool ool)
+static __always_inline void kuap_unlock(unsigned long addr, bool ool)
{
if (likely(addr != KUAP_ALL))
kuap_unlock_one(addr);
@@ -70,7 +70,7 @@ static inline void kuap_unlock(unsigned long addr, bool ool)
kuap_unlock_all_ool();
}

-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;

@@ -83,11 +83,11 @@ 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;
@@ -102,7 +102,7 @@ static inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kua
kuap_unlock(regs->kuap, false);
}

-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;

@@ -137,7 +137,7 @@ static __always_inline void __prevent_user_access(unsigned long dir)
kuap_lock_addr(kuap, true);
}

-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;

@@ -149,7 +149,7 @@ 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;
@@ -157,7 +157,7 @@ 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 d44c4ee2e8c3..f33e064b9f5f 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;
@@ -236,7 +236,7 @@ static __always_inline bool kuap_is_disabled(void)
}
#define kuap_is_disabled kuap_is_disabled

-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;
@@ -275,7 +275,7 @@ 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;
@@ -291,7 +291,7 @@ 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);

@@ -308,7 +308,7 @@ 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
@@ -338,7 +338,8 @@ 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).
@@ -381,12 +382,12 @@ 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)
@@ -401,7 +402,7 @@ 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();

@@ -412,7 +413,7 @@ 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 a02340535efa..132f1c7e1064 100644
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -59,14 +59,14 @@ 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
@@ -74,11 +74,11 @@ 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 1d53f38c5cd5..61067e4c8f22 100644
--- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
@@ -13,24 +13,24 @@

#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);

@@ -39,18 +39,18 @@ 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;

@@ -61,12 +61,12 @@ 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 07759ae9117b..416f3e0897d5 100644
--- a/arch/powerpc/include/asm/nohash/kup-booke.h
+++ b/arch/powerpc/include/asm/nohash/kup-booke.h
@@ -18,14 +18,14 @@

#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);
@@ -33,7 +33,7 @@ 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;
@@ -43,7 +43,7 @@ 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);
@@ -52,7 +52,7 @@ 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));

@@ -61,20 +61,20 @@ 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);

@@ -84,7 +84,7 @@ 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);
@@ -92,7 +92,7 @@ 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)))
--
2.40.1

Next message: Bjorn Andersson: "Re: [PATCH] cpufreq: qcom-cpufreq-hw: Use dev_err_probe() when failing to get icc paths"
Previous message: Christophe Leroy: "[PATCH v3 15/15] powerpc: Implement UACCESS validation on PPC32"
In reply to: Christophe Leroy: "[PATCH v3 15/15] powerpc: Implement UACCESS validation on PPC32"
Next in thread: Christophe Leroy: "[PATCH v3 08/15] objtool: Fix JUMP_ENTRY_SIZE for bi-arch like powerpc"
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