lkml.org 
[lkml]   [2021]   [Mar]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v1 8/8] powerpc/ptrace: Convert gpr32_set_common() to user access block
Date
Use user access block in gpr32_set_common() instead of
repetitive __get_user() which imply repetitive KUAP open/close.

To get it clean, force inlining of the small set of tiny functions
called inside the block.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/include/asm/ptrace.h | 2 +-
arch/powerpc/kernel/ptrace/ptrace-view.c | 30 ++++++++++++++----------
2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 975ba260006a..cb154fb7b605 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -222,7 +222,7 @@ do { \
} while (0)
#endif /* __powerpc64__ */

-static inline void set_trap(struct pt_regs *regs, unsigned long val)
+static __always_inline void set_trap(struct pt_regs *regs, unsigned long val)
{
regs->trap = (regs->trap & TRAP_FLAGS_MASK) | (val & ~TRAP_FLAGS_MASK);
}
diff --git a/arch/powerpc/kernel/ptrace/ptrace-view.c b/arch/powerpc/kernel/ptrace/ptrace-view.c
index 2bad8068f598..0923c94f684e 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-view.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-view.c
@@ -111,7 +111,7 @@ static unsigned long get_user_msr(struct task_struct *task)
return task->thread.regs->msr | task->thread.fpexc_mode;
}

-static int set_user_msr(struct task_struct *task, unsigned long msr)
+static __always_inline int set_user_msr(struct task_struct *task, unsigned long msr)
{
task->thread.regs->msr &= ~MSR_DEBUGCHANGE;
task->thread.regs->msr |= msr & MSR_DEBUGCHANGE;
@@ -147,7 +147,7 @@ static int set_user_dscr(struct task_struct *task, unsigned long dscr)
* We prevent mucking around with the reserved area of trap
* which are used internally by the kernel.
*/
-static int set_user_trap(struct task_struct *task, unsigned long trap)
+static __always_inline int set_user_trap(struct task_struct *task, unsigned long trap)
{
set_trap(task->thread.regs, trap);
return 0;
@@ -661,6 +661,9 @@ int gpr32_set_common(struct task_struct *target,
const compat_ulong_t __user *u = ubuf;
compat_ulong_t reg;

+ if (!kbuf && !user_read_access_begin(u, count))
+ return -EFAULT;
+
pos /= sizeof(reg);
count /= sizeof(reg);

@@ -669,8 +672,7 @@ int gpr32_set_common(struct task_struct *target,
regs[pos++] = *k++;
else
for (; count > 0 && pos < PT_MSR; --count) {
- if (__get_user(reg, u++))
- return -EFAULT;
+ unsafe_get_user(reg, u++, Efault);
regs[pos++] = reg;
}

@@ -678,8 +680,8 @@ int gpr32_set_common(struct task_struct *target,
if (count > 0 && pos == PT_MSR) {
if (kbuf)
reg = *k++;
- else if (__get_user(reg, u++))
- return -EFAULT;
+ else
+ unsafe_get_user(reg, u++, Efault);
set_user_msr(target, reg);
++pos;
--count;
@@ -692,24 +694,24 @@ int gpr32_set_common(struct task_struct *target,
++k;
} else {
for (; count > 0 && pos <= PT_MAX_PUT_REG; --count) {
- if (__get_user(reg, u++))
- return -EFAULT;
+ unsafe_get_user(reg, u++, Efault);
regs[pos++] = reg;
}
for (; count > 0 && pos < PT_TRAP; --count, ++pos)
- if (__get_user(reg, u++))
- return -EFAULT;
+ unsafe_get_user(reg, u++, Efault);
}

if (count > 0 && pos == PT_TRAP) {
if (kbuf)
reg = *k++;
- else if (__get_user(reg, u++))
- return -EFAULT;
+ else
+ unsafe_get_user(reg, u++, Efault);
set_user_trap(target, reg);
++pos;
--count;
}
+ if (!kbuf)
+ user_read_access_end();

kbuf = k;
ubuf = u;
@@ -717,6 +719,10 @@ int gpr32_set_common(struct task_struct *target,
count *= sizeof(reg);
return user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
(PT_TRAP + 1) * sizeof(reg), -1);
+
+Efault:
+ user_read_access_end();
+ return -EFAULT;
}

static int gpr32_get(struct task_struct *target,
--
2.25.0
\
 
 \ /
  Last update: 2021-03-10 18:59    [W:0.056 / U:1.448 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site