linux-kernel - [PATCH v2 0/7] riscv: convert bottom half of exception handling to C

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240720171232.1753-1-jszhang@kernel.org>
Date: Sun, 21 Jul 2024 01:12:25 +0800
From: Jisheng Zhang <jszhang@...nel.org>
To: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Charlie Jenkins <charlie@...osinc.com>,
	Deepak Gupta <debug@...osinc.com>,
	Clement Leger <cleger@...osinc.com>
Cc: linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/7] riscv: convert bottom half of exception handling to C

For readability, maintainability and future scalability, convert the
bottom half of the exception handling to C.

During the conversion, I found Anton fixed a performance issue[1]
and my patches will touch the same exception asm code, so this series
is applied against Anton's patch.

patch1 and patch2 are cleanup patches.
patch3~patch7 do the conversion and some cleanup/optimization
after conversion.

Mostly the assembly code is converted to C in a relatively
straightforward manner.

However, there are two modifications I need to mention:

1. the cause I.E the CSR_CAUSE value is passed to do_traps() via. 2nd
param, do_traps() doesn't get it from pt_regs because this way an extra
memory load is needed, the exception handling sits in hot code path,
every instruction matters.

2.To cope with SIFIVE_CIP_453 errata, it looks like we don't need
alternative mechanism any more after the asm->c conversion. Just
replace the excp_vect_table two entries.

Link: https://lore.kernel.org/linux-riscv/20240607061335.2197383-1-cyrilbur@tenstorrent.com/ [1]

since v1:
 - add two clean up patches
 - remove the two patches which fix imbalance in RAS, instead, explicitly
   mark this series is applied against one of them.
 - save cause in pt_regs prior to calling do_traps()
 - do more clean up and optimization after the asm->c conversion:
   staticalize and mark do_irq() as __always_inline.

Jisheng Zhang (7):
  riscv: traps: staticalize handle_break()
  riscv: traps: remove __visible annotation
  riscv: convert bottom half of exception handling to C
  riscv: errata: remove ALT_INSN_FAULT and ALT_PAGE_FAULT
  riscv: errata: sifive: remove NOMMU handling
  riscv: staticalize and remove asmlinkage from updated functions
  riscv: traps: mark do_irq() as __always_inline

 arch/riscv/errata/sifive/errata.c         | 25 +++++++---
 arch/riscv/errata/sifive/errata_cip_453.S |  4 --
 arch/riscv/include/asm/asm-prototypes.h   | 20 +-------
 arch/riscv/include/asm/entry-common.h     |  1 -
 arch/riscv/include/asm/errata_list.h      | 21 ++-------
 arch/riscv/kernel/entry.S                 | 57 +----------------------
 arch/riscv/kernel/kernel_mode_vector.c    |  2 +-
 arch/riscv/kernel/traps.c                 | 55 ++++++++++++++++++----
 8 files changed, 73 insertions(+), 112 deletions(-)

-- 
2.43.0