The following commit has been merged into the x86/fpu branch of tip:
Commit-ID: e84ba47e313dbc097bf859bb6e4f9219883d5f78
Gitweb: https://git.kernel.org/tip/e84ba47e313dbc097bf859bb6e4f9219883d5f78
Author: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
AuthorDate: Wed, 23 Jun 2021 14:02:19 +02:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Wed, 23 Jun 2021 19:44:24 +02:00
x86/fpu: Hook up PKRU into ptrace()
One nice thing about having PKRU be XSAVE-managed is that it gets naturally
exposed into the XSAVE-using ABIs. Now that XSAVE will not be used to
manage PKRU, these ABIs need to be manually enabled to deal with PKRU.
ptrace() uses copy_uabi_xstate_to_kernel() to collect the tracee's
XSTATE. As PKRU is not in the task's XSTATE buffer, use task->thread.pkru
for filling in up the ptrace buffer.
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/20210623121456.508770763@xxxxxxxxxxxxx
---
arch/x86/include/asm/fpu/xstate.h | 2 +-
arch/x86/kernel/fpu/regset.c | 10 ++++------
arch/x86/kernel/fpu/xstate.c | 25 ++++++++++++++++++-------
3 files changed, 23 insertions(+), 14 deletions(-)
diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index 6a0aaaf..4ff4a00 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -139,7 +139,7 @@ enum xstate_copy_mode {
};
struct membuf;
-void copy_xstate_to_uabi_buf(struct membuf to, struct xregs_state *xsave,
+void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
enum xstate_copy_mode mode);
#endif
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index 4575796..66ed317 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -78,7 +78,7 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
sizeof(fpu->state.fxsave));
}
- copy_xstate_to_uabi_buf(to, &fpu->state.xsave, XSTATE_COPY_FX);
+ copy_xstate_to_uabi_buf(to, target, XSTATE_COPY_FX);
return 0;
}
@@ -126,14 +126,12 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
struct membuf to)
{
- struct fpu *fpu = &target->thread.fpu;
-
if (!cpu_feature_enabled(X86_FEATURE_XSAVE))
return -ENODEV;
- sync_fpstate(fpu);
+ sync_fpstate(&target->thread.fpu);
- copy_xstate_to_uabi_buf(to, &fpu->state.xsave, XSTATE_COPY_XSAVE);
+ copy_xstate_to_uabi_buf(to, target, XSTATE_COPY_XSAVE);
return 0;
}
@@ -336,7 +334,7 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
struct membuf mb = { .p = &fxsave, .left = sizeof(fxsave) };
/* Handle init state optimized xstate correctly */
- copy_xstate_to_uabi_buf(mb, &fpu->state.xsave, XSTATE_COPY_FP);
+ copy_xstate_to_uabi_buf(mb, target, XSTATE_COPY_FP);
fx = &fxsave;
} else {
fx = &fpu->state.fxsave;
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index c513596..9fd124a 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -962,7 +962,7 @@ static void copy_feature(bool from_xstate, struct membuf *to, void *xstate,
/**
* copy_xstate_to_uabi_buf - Copy kernel saved xstate to a UABI buffer
* @to: membuf descriptor
- * @xsave: The kernel xstate buffer to copy from
+ * @tsk: The task from which to copy the saved xstate
* @copy_mode: The requested copy mode
*
* Converts from kernel XSAVE or XSAVES compacted format to UABI conforming
@@ -971,10 +971,11 @@ static void copy_feature(bool from_xstate, struct membuf *to, void *xstate,
*
* It supports partial copy but @to.pos always starts from zero.
*/
-void copy_xstate_to_uabi_buf(struct membuf to, struct xregs_state *xsave,
+void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
enum xstate_copy_mode copy_mode)
{
const unsigned int off_mxcsr = offsetof(struct fxregs_state, mxcsr);
+ struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
struct xregs_state *xinit = &init_fpstate.xsave;
struct xstate_header header;
unsigned int zerofrom;
@@ -1048,11 +1049,21 @@ void copy_xstate_to_uabi_buf(struct membuf to, struct xregs_state *xsave,
if (zerofrom < xstate_offsets[i])
membuf_zero(&to, xstate_offsets[i] - zerofrom);
- copy_feature(header.xfeatures & BIT_ULL(i), &to,
- __raw_xsave_addr(xsave, i),
- __raw_xsave_addr(xinit, i),
- xstate_sizes[i]);
-
+ if (i == XFEATURE_PKRU) {
+ struct pkru_state pkru = {0};
+ /*
+ * PKRU is not necessarily up to date in the
+ * thread's XSAVE buffer. Fill this part from the
+ * per-thread storage.
+ */
+ pkru.pkru = tsk->thread.pkru;
+ membuf_write(&to, &pkru, sizeof(pkru));
+ } else {
+ copy_feature(header.xfeatures & BIT_ULL(i), &to,
+ __raw_xsave_addr(xsave, i),
+ __raw_xsave_addr(xinit, i),
+ xstate_sizes[i]);
+ }
/*
* Keep track of the last copied state in the non-compacted
* target buffer for gap zeroing.
|