This patch converts emulate_spe() to using user_access_being
logic.
Since commit 662bbcb2747c ("mm, sched: Allow uaccess in atomic with
pagefault_disable()"), might_fault() doesn't fire when called from
sections where pagefaults are disabled, which must be the case
when using _inatomic variants of __get_user and __put_user. So
the might_fault() in user_access_begin() is not a problem.
There was a verification of user_mode() together with the access_ok(),
but the function returns in case !user_mode() immediately after
the access_ok() verification, so removing that test has no effect.
Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
---
arch/powerpc/kernel/align.c | 61 ++++++++++++++++++++-----------------
1 file changed, 33 insertions(+), 28 deletions(-)
diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c
index c7797eb958c7..c4d7b445b459 100644
--- a/arch/powerpc/kernel/align.c
+++ b/arch/powerpc/kernel/align.c
@@ -107,7 +107,6 @@ static struct aligninfo spe_aligninfo[32] = {
static int emulate_spe(struct pt_regs *regs, unsigned int reg,
struct ppc_inst ppc_instr)
{
- int ret;
union {
u64 ll;
u32 w[2];
@@ -127,11 +126,6 @@ static int emulate_spe(struct pt_regs *regs, unsigned int
reg,
nb = spe_aligninfo[instr].len;
flags = spe_aligninfo[instr].flags;
- /* Verify the address of the operand */
- if (unlikely(user_mode(regs) &&
- !access_ok(addr, nb)))
- return -EFAULT;
-
/* userland only */
if (unlikely(!user_mode(regs)))
return 0;
@@ -169,26 +163,27 @@ static int emulate_spe(struct pt_regs *regs, unsigned int
reg,
}
} else {
temp.ll = data.ll = 0;
- ret = 0;
p = addr;
+ if (!user_read_access_begin(addr, nb))
+ return -EFAULT;
+
switch (nb) {
case 8:
- ret |= __get_user_inatomic(temp.v[0], p++);
- ret |= __get_user_inatomic(temp.v[1], p++);
- ret |= __get_user_inatomic(temp.v[2], p++);
- ret |= __get_user_inatomic(temp.v[3], p++);
+ unsafe_get_user(temp.v[0], p++, Efault_read);
+ unsafe_get_user(temp.v[1], p++, Efault_read);
+ unsafe_get_user(temp.v[2], p++, Efault_read);
+ unsafe_get_user(temp.v[3], p++, Efault_read);
fallthrough;
case 4:
- ret |= __get_user_inatomic(temp.v[4], p++);
- ret |= __get_user_inatomic(temp.v[5], p++);
+ unsafe_get_user(temp.v[4], p++, Efault_read);
+ unsafe_get_user(temp.v[5], p++, Efault_read);
fallthrough;
case 2:
- ret |= __get_user_inatomic(temp.v[6], p++);
- ret |= __get_user_inatomic(temp.v[7], p++);
- if (unlikely(ret))
- return -EFAULT;
+ unsafe_get_user(temp.v[6], p++, Efault_read);
+ unsafe_get_user(temp.v[7], p++, Efault_read);
}
+ user_read_access_end();
switch (instr) {
case EVLDD:
@@ -255,31 +250,41 @@ static int emulate_spe(struct pt_regs *regs, unsigned int
reg,
/* Store result to memory or update registers */
if (flags & ST) {
- ret = 0;
p = addr;
+
+ if (!user_read_access_begin(addr, nb))
+ return -EFAULT;
+
switch (nb) {
case 8:
- ret |= __put_user_inatomic(data.v[0], p++);
- ret |= __put_user_inatomic(data.v[1], p++);
- ret |= __put_user_inatomic(data.v[2], p++);
- ret |= __put_user_inatomic(data.v[3], p++);
+ unsafe_put_user(data.v[0], p++, Efault_write);
+ unsafe_put_user(data.v[1], p++, Efault_write);
+ unsafe_put_user(data.v[2], p++, Efault_write);
+ unsafe_put_user(data.v[3], p++, Efault_write);
fallthrough;
case 4:
- ret |= __put_user_inatomic(data.v[4], p++);
- ret |= __put_user_inatomic(data.v[5], p++);
+ unsafe_put_user(data.v[4], p++, Efault_write);
+ unsafe_put_user(data.v[5], p++, Efault_write);
fallthrough;
case 2:
- ret |= __put_user_inatomic(data.v[6], p++);
- ret |= __put_user_inatomic(data.v[7], p++);
+ unsafe_put_user(data.v[6], p++, Efault_write);
+ unsafe_put_user(data.v[7], p++, Efault_write);
}
- if (unlikely(ret))
- return -EFAULT;
+ user_write_access_end();
} else {
*evr = data.w[0];
regs->gpr[reg] = data.w[1];
}
return 1;
+
+Efault_read:
+ user_read_access_end();
+ return -EFAULT;
+
+Efault_write:
+ user_write_access_end();
+ return -EFAULT;
}
#endif /* CONFIG_SPE */
--
2.25.0
