On 10/31/23 09:53, Xiang W wrote:
setjmp can be called in set_resume.
Unfortunately this is not possible. A longjmp buffer only stores
register values and not the stack content.
Let's assume that setjmp() is moved into set_resume():
Let a function call set_resume(). The caller's address will be on the
stack. Once the set_resume returns and the caller invokes another
function the original stack content will be overwritten. When an
exception occurs the longjmp will reenter set_resume() with the original
stack pointer value pointing to a stack that does not match the original
call to set_resume and set_resume will return to a random address.
Best regards
Heinrich
Regards,
Xiang W
Heinrich Schuchardt <heinrich.schucha...@canonical.com> 于2023年10月29日周日 16:56写道：
If CSRs like seed are readable by S-mode, may not be determinable by
S-mode. For safe driver probing allow to resume via a longjmp after an
exception.
Signed-off-by: Heinrich Schuchardt <heinrich.schucha...@canonical.com>
---
v2:
new patch
---
arch/riscv/lib/interrupts.c | 13 +++++++++++++
include/interrupt.h | 22 ++++++++++++++++++++++
2 files changed, 35 insertions(+)
create mode 100644 include/interrupt.h
diff --git a/arch/riscv/lib/interrupts.c b/arch/riscv/lib/interrupts.c
index 02dbcfd423..a26ccc721f 100644
--- a/arch/riscv/lib/interrupts.c
+++ b/arch/riscv/lib/interrupts.c
@@ -12,6 +12,7 @@
#include <linux/compat.h>
#include <efi_loader.h>
#include <hang.h>
+#include <interrupt.h>
#include <irq_func.h>
#include <asm/global_data.h>
#include <asm/ptrace.h>
@@ -21,6 +22,13 @@
DECLARE_GLOBAL_DATA_PTR;
+static struct resume_data *resume;
+
+void set_resume(struct resume_data *data)
+{
+ resume = data;
+}
+
static void show_efi_loaded_images(uintptr_t epc)
{
efi_print_image_infos((void *)epc);
@@ -105,6 +113,11 @@ static void _exit_trap(ulong code, ulong epc, ulong tval,
struct pt_regs *regs)
"Store/AMO page fault",
};
+ if (resume) {
+ resume->code = code;
+ longjmp(resume->jump, 1);
+ }
+
if (code < ARRAY_SIZE(exception_code))
printf("Unhandled exception: %s\n", exception_code[code]);
else
diff --git a/include/interrupt.h b/include/interrupt.h
new file mode 100644
index 0000000000..1baa60bcf2
--- /dev/null
+++ b/include/interrupt.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <asm/setjmp.h>
+
+/**
+ * struct resume_data - data for resume after interrupt
+ */
+struct resume_data {
+ /** @jump: longjmp buffer */
+ jmp_buf jump;
+ /** @code: exception code */
+ ulong code;
+};
+
+/**
+ * set_resume() - set longjmp buffer for resuming after interrupt
+ *
+ * When resuming the exception code will be returned in @data->code.
+ *
+ * @data: pointer to structure with longjmp address
+ */
+void set_resume(struct resume_data *data);
--
2.40.1
