[PATCH v2] lib: sbi: Improve fatal error handling
Atish Patra
atishp at atishpatra.org
Tue Nov 30 13:53:00 PST 2021
On Mon, Nov 29, 2021 at 9:53 PM Anup Patel <anup.patel at wdc.com> wrote:
>
> From: Jessica Clarke <jrtc27 at jrtc27.com>
>
> BUG and BUG_ON are not informative and are rather lazy interfaces, only
> telling the user that something went wrong in a given function, but not
> what, requiring the user to find the sources corresponding to their
> firmware (which may not be available) and figure out how that BUG(_ON)
> was hit. Even SBI_ASSERT in its current form, which does include the
> condition that triggered it in the output, isn't necessarily very
> informative. In some cases, the error may be fixable by the user, but
> they need to know the problem in order to have any hope of fixing it.
> It's also a nuisance for developers, whose development trees may have
> changed significantly since the release in question being used, and so
> line numbers can make it harder for them to understand which error case
> a user has hit.
>
> This patch introduces a new sbi_panic function which is printf-like,
> allowing detailed error messages to be printed to the console. BUG and
> BUG_ON are removed, since the former is just a worse form of sbi_panic
> and the latter is a worse version of SBI_ASSERT. Finally, SBI_ASSERT is
> augmented to take a set of arguments to pass to sbi_panic on failure,
> used like so (sbi_boot_print_hart's current error case, which currently
> manually calls sbi_printf and sbi_hart_hang):
>
> SBI_ASSERT(xlen >= 1, ("Error %d getting MISA XLEN\n", xlen));
>
> The existing users of BUG are replaced with calls to sbi_panic along
> with informative error messages. BUG_ON and SBI_ASSERT were unused (and,
> in the case of SBI_ASSERT, remain unused).
>
> Many existing users of sbi_hart_hang should be converted to use either
> sbi_panic or SBI_ASSERT after this commit.
>
> Signed-off-by: Jessica Clarke <jrtc27 at jrtc27.com>
> Reviewed-by: Anup Patel <anup.patel at wdc.com>
> Reviewed-by: Xiang W <wxjstz at 126.com>
> ---
> Changes since v1:
> - Update patch suject
> - Fixed typo in patch description
> - Remove "#include <sbi/sbi_hart.h>" from sbi_console.h
> ---
> include/sbi/sbi_console.h | 23 +++++------------------
> lib/sbi/riscv_asm.c | 7 ++++---
> lib/sbi/sbi_console.c | 14 ++++++++++++++
> platform/generic/sifive_fu740.c | 1 +
> 4 files changed, 24 insertions(+), 21 deletions(-)
>
> diff --git a/include/sbi/sbi_console.h b/include/sbi/sbi_console.h
> index 28b4a79..e15b55d 100644
> --- a/include/sbi/sbi_console.h
> +++ b/include/sbi/sbi_console.h
> @@ -11,7 +11,6 @@
> #define __SBI_CONSOLE_H__
>
> #include <sbi/sbi_types.h>
> -#include <sbi/sbi_hart.h>
>
> struct sbi_console_device {
> /** Name of the console device */
> @@ -44,6 +43,8 @@ int __printf(1, 2) sbi_printf(const char *format, ...);
>
> int __printf(1, 2) sbi_dprintf(const char *format, ...);
>
> +void __printf(1, 2) __attribute__((noreturn)) sbi_panic(const char *format, ...);
> +
> const struct sbi_console_device *sbi_console_get_device(void);
>
> void sbi_console_set_device(const struct sbi_console_device *dev);
> @@ -52,23 +53,9 @@ struct sbi_scratch;
>
> int sbi_console_init(struct sbi_scratch *scratch);
>
> -#define BUG() do { \
> - sbi_printf("BUG: failure at %s:%d/%s()!\n", \
> - __FILE__, __LINE__, __func__); \
> - sbi_hart_hang(); \
> -} while (0)
> -
> -#define BUG_ON(cond) do { \
> - if (cond) \
> - BUG(); \
> -} while (0)
> -
> -#define SBI_ASSERT(cond) do { \
> - if (!(cond)) { \
> - sbi_printf("ASSERT: %s:%d/%s(): Assertion `%s` failed.\n", \
> - __FILE__,__LINE__,__func__, #cond);\
> - sbi_hart_hang(); \
> - } \
> +#define SBI_ASSERT(cond, args) do { \
> + if (unlikely(!(cond))) \
> + sbi_panic args; \
> } while (0)
>
> #endif
> diff --git a/lib/sbi/riscv_asm.c b/lib/sbi/riscv_asm.c
> index 1642ac6..2e2e148 100644
> --- a/lib/sbi/riscv_asm.c
> +++ b/lib/sbi/riscv_asm.c
> @@ -76,7 +76,8 @@ void misa_string(int xlen, char *out, unsigned int out_sz)
> out[pos++] = '8';
> break;
> default:
> - BUG();
> + sbi_panic("%s: Unknown misa.MXL encoding %d",
> + __func__, xlen);
> return;
> }
> }
> @@ -145,7 +146,7 @@ unsigned long csr_read_num(int csr_num)
> #endif
>
> default:
> - BUG();
> + sbi_panic("%s: Unknown CSR %#x", __func__, csr_num);
> break;
> };
>
> @@ -213,7 +214,7 @@ void csr_write_num(int csr_num, unsigned long val)
> switchcase_csr_write_16(CSR_MHPMEVENT16, val)
>
> default:
> - BUG();
> + sbi_panic("%s: Unknown CSR %#x", __func__, csr_num);
> break;
> };
>
> diff --git a/lib/sbi/sbi_console.c b/lib/sbi/sbi_console.c
> index 29eede3..34c843d 100644
> --- a/lib/sbi/sbi_console.c
> +++ b/lib/sbi/sbi_console.c
> @@ -9,6 +9,7 @@
>
> #include <sbi/riscv_locks.h>
> #include <sbi/sbi_console.h>
> +#include <sbi/sbi_hart.h>
> #include <sbi/sbi_platform.h>
> #include <sbi/sbi_scratch.h>
>
> @@ -397,6 +398,19 @@ int sbi_dprintf(const char *format, ...)
> return retval;
> }
>
> +void sbi_panic(const char *format, ...)
> +{
> + va_list args;
> +
> + spin_lock(&console_out_lock);
> + va_start(args, format);
> + print(NULL, NULL, format, args);
> + va_end(args);
> + spin_unlock(&console_out_lock);
> +
> + sbi_hart_hang();
> +}
> +
> const struct sbi_console_device *sbi_console_get_device(void)
> {
> return console_dev;
> diff --git a/platform/generic/sifive_fu740.c b/platform/generic/sifive_fu740.c
> index 3152152..333b3fb 100644
> --- a/platform/generic/sifive_fu740.c
> +++ b/platform/generic/sifive_fu740.c
> @@ -12,6 +12,7 @@
> #include <platform_override.h>
> #include <libfdt.h>
> #include <sbi/sbi_error.h>
> +#include <sbi/sbi_hart.h>
> #include <sbi/sbi_system.h>
> #include <sbi/sbi_console.h>
> #include <sbi_utils/fdt/fdt_helper.h>
> --
> 2.25.1
>
Reviewed-by: Atish Patra <atishp at rivosinc.com>
--
Regards,
Atish
More information about the opensbi
mailing list