In preparation of implementing user_access_begin and friends
on powerpc, allow_user_access() need to be prepared for
user_access_begin()
user_access_end() doesn't provide the address and size which
were passed to user_access_begin(), required by prevent_user_access()
to know which segment to modify. But user_access_end() takes an
opaque value returned by user_access_begin().
Make allow_user_access() return the value it writes to current->kuap.
This will allow user_access_end() to recalculate the segment range
without having to read current->kuap.
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
v3: Replaces the patch "Prepare prevent_user_access() for user_access_end()"
---
arch/powerpc/include/asm/book3s/32/kup.h | 15 ++++++++++-----
arch/powerpc/include/asm/book3s/64/kup-radix.h | 7 +++++--
arch/powerpc/include/asm/kup.h | 8 ++++++--
arch/powerpc/include/asm/nohash/32/kup-8xx.h | 6 ++++--
4 files changed, 25 insertions(+), 11 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index 3c1798e56b55..128dcbf3a19d 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -102,23 +102,28 @@ static inline void kuap_update_sr(u32 sr, u32 addr, u32 end)
isync(); /* Context sync required after mtsrin() */
}
-static __always_inline void allow_user_access(void __user *to, const void __user *from,
- u32 size, unsigned long dir)
+/* Make sure we never return 0. We only use top and bottom 4 bits */
+static __always_inline unsigned long
+allow_user_access(void __user *to, const void __user *from, u32 size, unsigned long dir)
{
u32 addr, end;
+ unsigned long kuap;
BUILD_BUG_ON(!__builtin_constant_p(dir));
if (!(dir & KUAP_W))
- return;
+ return 0x100;
addr = (__force u32)to;
if (unlikely(addr >= TASK_SIZE || !size))
- return;
+ return 0x100;
end = min(addr + size, TASK_SIZE);
- current->thread.kuap = (addr & 0xf0000000) | ((((end - 1) >> 28) + 1) & 0xf);
+ kuap = (addr & 0xf0000000) | ((((end - 1) >> 28) + 1) & 0xf);
+ current->thread.kuap = kuap;
kuap_update_sr(mfsrin(addr) & ~SR_KS, addr, end); /* Clear Ks */
+
+ return kuap;
}
static __always_inline void prevent_user_access(void __user *to, const void __user *from,
diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h b/arch/powerpc/include/asm/book3s/64/kup-radix.h
index f11315306d41..183f0c87017b 100644
--- a/arch/powerpc/include/asm/book3s/64/kup-radix.h
+++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h
@@ -77,8 +77,9 @@ static inline void set_kuap(unsigned long value)
isync();
}
-static __always_inline void allow_user_access(void __user *to, const void __user *from,
- unsigned long size, unsigned long dir)
+static __always_inline unsigned long
+allow_user_access(void __user *to, const void __user *from,
+ unsigned long size, unsigned long dir)
{
// This is written so we can resolve to a single case at build time
BUILD_BUG_ON(!__builtin_constant_p(dir));
@@ -88,6 +89,8 @@ static __always_inline void allow_user_access(void __user *to, const void __user
set_kuap(AMR_KUAP_BLOCK_READ);
else
set_kuap(0);
+
+ return 1;
}
static inline void prevent_user_access(void __user *to, const void __user *from,
diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
index ff57bfcb88f7..691fec5afd4a 100644
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -45,8 +45,12 @@ static inline void setup_kuep(bool disabled) { }
void setup_kuap(bool disabled);
#else
static inline void setup_kuap(bool disabled) { }
-static inline void allow_user_access(void __user *to, const void __user *from,
- unsigned long size, unsigned long dir) { }
+static inline unsigned long allow_user_access(void __user *to, const void __user *from,
+ unsigned long size, unsigned long dir)
+{
+ return 1;
+}
+
static inline void prevent_user_access(void __user *to, const void __user *from,
unsigned long size, unsigned long dir) { }
static inline bool
diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
index 1d70c80366fd..ee673d3c0ab6 100644
--- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
@@ -34,10 +34,12 @@
#include <asm/reg.h>
-static inline void allow_user_access(void __user *to, const void __user *from,
- unsigned long size, unsigned long dir)
+static inline unsigned long allow_user_access(void __user *to, const void __user *from,
+ unsigned long size, unsigned long dir)
{
mtspr(SPRN_MD_AP, MD_APG_INIT);
+
+ return 1;
}
static inline void prevent_user_access(void __user *to, const void __user *from,
--
2.25.0
