Commit edaed168 authored by Linus Torvalds's avatar Linus Torvalds

Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86/pti update from Thomas Gleixner:
 "Just a single change from the anti-performance departement:

   - Add a new PR_SPEC_DISABLE_NOEXEC option which allows to apply the
     speculation protections on a process without inheriting the state
     on exec.

     This remedies a situation where a Java-launcher has speculation
     protections enabled because that's the default for JVMs which
     causes the launched regular harmless processes to inherit the
     protection state which results in unintended performance
     degradation"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/speculation: Add PR_SPEC_DISABLE_NOEXEC
parents 78f86013 71368af9
...@@ -28,9 +28,9 @@ PR_GET_SPECULATION_CTRL returns the state of the speculation misfeature ...@@ -28,9 +28,9 @@ PR_GET_SPECULATION_CTRL returns the state of the speculation misfeature
which is selected with arg2 of prctl(2). The return value uses bits 0-3 with which is selected with arg2 of prctl(2). The return value uses bits 0-3 with
the following meaning: the following meaning:
==== ===================== =================================================== ==== ====================== ==================================================
Bit Define Description Bit Define Description
==== ===================== =================================================== ==== ====================== ==================================================
0 PR_SPEC_PRCTL Mitigation can be controlled per task by 0 PR_SPEC_PRCTL Mitigation can be controlled per task by
PR_SET_SPECULATION_CTRL. PR_SET_SPECULATION_CTRL.
1 PR_SPEC_ENABLE The speculation feature is enabled, mitigation is 1 PR_SPEC_ENABLE The speculation feature is enabled, mitigation is
...@@ -39,7 +39,9 @@ Bit Define Description ...@@ -39,7 +39,9 @@ Bit Define Description
enabled. enabled.
3 PR_SPEC_FORCE_DISABLE Same as PR_SPEC_DISABLE, but cannot be undone. A 3 PR_SPEC_FORCE_DISABLE Same as PR_SPEC_DISABLE, but cannot be undone. A
subsequent prctl(..., PR_SPEC_ENABLE) will fail. subsequent prctl(..., PR_SPEC_ENABLE) will fail.
==== ===================== =================================================== 4 PR_SPEC_DISABLE_NOEXEC Same as PR_SPEC_DISABLE, but the state will be
cleared on :manpage:`execve(2)`.
==== ====================== ==================================================
If all bits are 0 the CPU is not affected by the speculation misfeature. If all bits are 0 the CPU is not affected by the speculation misfeature.
...@@ -92,6 +94,7 @@ Speculation misfeature controls ...@@ -92,6 +94,7 @@ Speculation misfeature controls
* prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_ENABLE, 0, 0); * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_ENABLE, 0, 0);
* prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_DISABLE, 0, 0); * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_DISABLE, 0, 0);
* prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_FORCE_DISABLE, 0, 0); * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_FORCE_DISABLE, 0, 0);
* prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_DISABLE_NOEXEC, 0, 0);
- PR_SPEC_INDIR_BRANCH: Indirect Branch Speculation in User Processes - PR_SPEC_INDIR_BRANCH: Indirect Branch Speculation in User Processes
(Mitigate Spectre V2 style attacks against user processes) (Mitigate Spectre V2 style attacks against user processes)
......
...@@ -798,15 +798,25 @@ static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl) ...@@ -798,15 +798,25 @@ static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
if (task_spec_ssb_force_disable(task)) if (task_spec_ssb_force_disable(task))
return -EPERM; return -EPERM;
task_clear_spec_ssb_disable(task); task_clear_spec_ssb_disable(task);
task_clear_spec_ssb_noexec(task);
task_update_spec_tif(task); task_update_spec_tif(task);
break; break;
case PR_SPEC_DISABLE: case PR_SPEC_DISABLE:
task_set_spec_ssb_disable(task); task_set_spec_ssb_disable(task);
task_clear_spec_ssb_noexec(task);
task_update_spec_tif(task); task_update_spec_tif(task);
break; break;
case PR_SPEC_FORCE_DISABLE: case PR_SPEC_FORCE_DISABLE:
task_set_spec_ssb_disable(task); task_set_spec_ssb_disable(task);
task_set_spec_ssb_force_disable(task); task_set_spec_ssb_force_disable(task);
task_clear_spec_ssb_noexec(task);
task_update_spec_tif(task);
break;
case PR_SPEC_DISABLE_NOEXEC:
if (task_spec_ssb_force_disable(task))
return -EPERM;
task_set_spec_ssb_disable(task);
task_set_spec_ssb_noexec(task);
task_update_spec_tif(task); task_update_spec_tif(task);
break; break;
default: default:
...@@ -885,6 +895,8 @@ static int ssb_prctl_get(struct task_struct *task) ...@@ -885,6 +895,8 @@ static int ssb_prctl_get(struct task_struct *task)
case SPEC_STORE_BYPASS_PRCTL: case SPEC_STORE_BYPASS_PRCTL:
if (task_spec_ssb_force_disable(task)) if (task_spec_ssb_force_disable(task))
return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE; return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
if (task_spec_ssb_noexec(task))
return PR_SPEC_PRCTL | PR_SPEC_DISABLE_NOEXEC;
if (task_spec_ssb_disable(task)) if (task_spec_ssb_disable(task))
return PR_SPEC_PRCTL | PR_SPEC_DISABLE; return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
return PR_SPEC_PRCTL | PR_SPEC_ENABLE; return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
......
...@@ -255,6 +255,18 @@ void arch_setup_new_exec(void) ...@@ -255,6 +255,18 @@ void arch_setup_new_exec(void)
/* If cpuid was previously disabled for this task, re-enable it. */ /* If cpuid was previously disabled for this task, re-enable it. */
if (test_thread_flag(TIF_NOCPUID)) if (test_thread_flag(TIF_NOCPUID))
enable_cpuid(); enable_cpuid();
/*
* Don't inherit TIF_SSBD across exec boundary when
* PR_SPEC_DISABLE_NOEXEC is used.
*/
if (test_thread_flag(TIF_SSBD) &&
task_spec_ssb_noexec(current)) {
clear_thread_flag(TIF_SSBD);
task_clear_spec_ssb_disable(current);
task_clear_spec_ssb_noexec(current);
speculation_ctrl_update(task_thread_info(current)->flags);
}
} }
static inline void switch_to_bitmap(struct thread_struct *prev, static inline void switch_to_bitmap(struct thread_struct *prev,
......
...@@ -1453,6 +1453,7 @@ static inline bool is_percpu_thread(void) ...@@ -1453,6 +1453,7 @@ static inline bool is_percpu_thread(void)
#define PFA_SPEC_SSB_FORCE_DISABLE 4 /* Speculative Store Bypass force disabled*/ #define PFA_SPEC_SSB_FORCE_DISABLE 4 /* Speculative Store Bypass force disabled*/
#define PFA_SPEC_IB_DISABLE 5 /* Indirect branch speculation restricted */ #define PFA_SPEC_IB_DISABLE 5 /* Indirect branch speculation restricted */
#define PFA_SPEC_IB_FORCE_DISABLE 6 /* Indirect branch speculation permanently restricted */ #define PFA_SPEC_IB_FORCE_DISABLE 6 /* Indirect branch speculation permanently restricted */
#define PFA_SPEC_SSB_NOEXEC 7 /* Speculative Store Bypass clear on execve() */
#define TASK_PFA_TEST(name, func) \ #define TASK_PFA_TEST(name, func) \
static inline bool task_##func(struct task_struct *p) \ static inline bool task_##func(struct task_struct *p) \
...@@ -1481,6 +1482,10 @@ TASK_PFA_TEST(SPEC_SSB_DISABLE, spec_ssb_disable) ...@@ -1481,6 +1482,10 @@ TASK_PFA_TEST(SPEC_SSB_DISABLE, spec_ssb_disable)
TASK_PFA_SET(SPEC_SSB_DISABLE, spec_ssb_disable) TASK_PFA_SET(SPEC_SSB_DISABLE, spec_ssb_disable)
TASK_PFA_CLEAR(SPEC_SSB_DISABLE, spec_ssb_disable) TASK_PFA_CLEAR(SPEC_SSB_DISABLE, spec_ssb_disable)
TASK_PFA_TEST(SPEC_SSB_NOEXEC, spec_ssb_noexec)
TASK_PFA_SET(SPEC_SSB_NOEXEC, spec_ssb_noexec)
TASK_PFA_CLEAR(SPEC_SSB_NOEXEC, spec_ssb_noexec)
TASK_PFA_TEST(SPEC_SSB_FORCE_DISABLE, spec_ssb_force_disable) TASK_PFA_TEST(SPEC_SSB_FORCE_DISABLE, spec_ssb_force_disable)
TASK_PFA_SET(SPEC_SSB_FORCE_DISABLE, spec_ssb_force_disable) TASK_PFA_SET(SPEC_SSB_FORCE_DISABLE, spec_ssb_force_disable)
......
...@@ -219,6 +219,7 @@ struct prctl_mm_map { ...@@ -219,6 +219,7 @@ struct prctl_mm_map {
# define PR_SPEC_ENABLE (1UL << 1) # define PR_SPEC_ENABLE (1UL << 1)
# define PR_SPEC_DISABLE (1UL << 2) # define PR_SPEC_DISABLE (1UL << 2)
# define PR_SPEC_FORCE_DISABLE (1UL << 3) # define PR_SPEC_FORCE_DISABLE (1UL << 3)
# define PR_SPEC_DISABLE_NOEXEC (1UL << 4)
/* Reset arm64 pointer authentication keys */ /* Reset arm64 pointer authentication keys */
#define PR_PAC_RESET_KEYS 54 #define PR_PAC_RESET_KEYS 54
......
...@@ -219,6 +219,7 @@ struct prctl_mm_map { ...@@ -219,6 +219,7 @@ struct prctl_mm_map {
# define PR_SPEC_ENABLE (1UL << 1) # define PR_SPEC_ENABLE (1UL << 1)
# define PR_SPEC_DISABLE (1UL << 2) # define PR_SPEC_DISABLE (1UL << 2)
# define PR_SPEC_FORCE_DISABLE (1UL << 3) # define PR_SPEC_FORCE_DISABLE (1UL << 3)
# define PR_SPEC_DISABLE_NOEXEC (1UL << 4)
/* Reset arm64 pointer authentication keys */ /* Reset arm64 pointer authentication keys */
#define PR_PAC_RESET_KEYS 54 #define PR_PAC_RESET_KEYS 54
......
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