@@ -178,12 +178,6 @@ static __kprobes unsigned long _sdei_handler(struct pt_regs *regs,
sdei_api_event_context(i, ®s->regs[i]);
}
- /*
- * We didn't take an exception to get here, set PAN. UAO will be cleared
- * by sdei_event_handler()s force_uaccess_begin() call.
- */
- __uaccess_enable_hw_pan();
-
err = sdei_event_handler(regs, arg);
if (err)
return SDEI_EV_FAILED;
@@ -227,6 +221,16 @@ asmlinkage __kprobes notrace unsigned long
__sdei_handler(struct pt_regs *regs, struct sdei_registered_event *arg)
{
unsigned long ret;
+ mm_segment_t orig_addr_limit;
+
+ /*
+ * We didn't take an exception to get here, so the HW hasn't set PAN or
+ * cleared UAO, and the exception entry code hasn't reset addr_limit.
+ * Set PAN, then use force_uaccess_begin() to clear UAO and reset
+ * addr_limit.
+ */
+ __uaccess_enable_hw_pan();
+ orig_addr_limit = force_uaccess_begin();
nmi_enter();
@@ -234,5 +238,7 @@ __sdei_handler(struct pt_regs *regs, struct sdei_registered_event *arg)
nmi_exit();
+ force_uaccess_end(orig_addr_limit);
+
return ret;
}
@@ -31,7 +31,6 @@
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
-#include <linux/uaccess.h>
/*
* The call to use to reach the firmware.
@@ -1125,26 +1124,13 @@ int sdei_event_handler(struct pt_regs *regs,
struct sdei_registered_event *arg)
{
int err;
- mm_segment_t orig_addr_limit;
u32 event_num = arg->event_num;
- /*
- * Save restore 'fs'.
- * The architecture's entry code save/restores 'fs' when taking an
- * exception from the kernel. This ensures addr_limit isn't inherited
- * if you interrupted something that allowed the uaccess routines to
- * access kernel memory.
- * Do the same here because this doesn't come via the same entry code.
- */
- orig_addr_limit = force_uaccess_begin();
-
err = arg->callback(event_num, regs, arg->callback_arg);
if (err)
pr_err_ratelimited("event %u on CPU %u failed with error: %d\n",
event_num, smp_processor_id(), err);
- force_uaccess_end(orig_addr_limit);
-
return err;
}
NOKPROBE_SYMBOL(sdei_event_handler);
The SDEI support code is split across arch/arm64/ and drivers/firmware/, largley this is split so that the arch-specific portions are under arch/arm64, and the management logic is under drivers/firmware/. However, exception entry fixups are currently under drivers/firmware. Let's move the exception entry fixups under arch/arm64/. This de-clutters the management logic, and puts all the arch-specific portions in one place. Doing this also allows the fixups to be applied earlier, so things like PAN and UAO will be in a known good state before we run other logic. This will also make subsequent refactoring easier. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christoph Hellwig <hch@lst.de> Cc: James Morse <james.morse@arm.com> Cc: Will Deacon <will@kernel.org> --- arch/arm64/kernel/sdei.c | 18 ++++++++++++------ drivers/firmware/arm_sdei.c | 14 -------------- 2 files changed, 12 insertions(+), 20 deletions(-)