diff options
Diffstat (limited to '0030-xen-Work-around-Clang-IAS-macro-expansion-bug.patch')
| -rw-r--r-- | 0030-xen-Work-around-Clang-IAS-macro-expansion-bug.patch | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/0030-xen-Work-around-Clang-IAS-macro-expansion-bug.patch b/0030-xen-Work-around-Clang-IAS-macro-expansion-bug.patch new file mode 100644 index 0000000..a92f2f0 --- /dev/null +++ b/0030-xen-Work-around-Clang-IAS-macro-expansion-bug.patch @@ -0,0 +1,115 @@ +From 2b8f72a6b40dafc3fb40bce100cd62c4a377535a Mon Sep 17 00:00:00 2001 +From: Andrew Cooper <andrew.cooper3@citrix.com> +Date: Fri, 3 Mar 2023 08:14:57 +0100 +Subject: [PATCH 30/61] xen: Work around Clang-IAS macro \@ expansion bug + +https://github.com/llvm/llvm-project/issues/60792 + +It turns out that Clang-IAS does not expand \@ uniquely in a translaition +unit, and the XSA-426 change tickles this bug: + + <instantiation>:4:1: error: invalid symbol redefinition + .L1_fill_rsb_loop: + ^ + make[3]: *** [Rules.mk:247: arch/x86/acpi/cpu_idle.o] Error 1 + +Extend DO_OVERWRITE_RSB with an optional parameter so C callers can mix %= in +too, which Clang does seem to expand properly. + +Fixes: 63305e5392ec ("x86/spec-ctrl: Mitigate Cross-Thread Return Address Predictions") +Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> +Reviewed-by: Jan Beulich <jbeulich@suse.com> +master commit: a2adacff0b91cc7b977abb209dc419a2ef15963f +master date: 2023-02-24 17:44:29 +0000 +--- + xen/include/asm-x86/spec_ctrl.h | 4 ++-- + xen/include/asm-x86/spec_ctrl_asm.h | 23 ++++++++++++++--------- + 2 files changed, 16 insertions(+), 11 deletions(-) + +diff --git a/xen/include/asm-x86/spec_ctrl.h b/xen/include/asm-x86/spec_ctrl.h +index 391973ef6a..a431fea587 100644 +--- a/xen/include/asm-x86/spec_ctrl.h ++++ b/xen/include/asm-x86/spec_ctrl.h +@@ -83,7 +83,7 @@ static always_inline void spec_ctrl_new_guest_context(void) + wrmsrl(MSR_PRED_CMD, PRED_CMD_IBPB); + + /* (ab)use alternative_input() to specify clobbers. */ +- alternative_input("", "DO_OVERWRITE_RSB", X86_BUG_IBPB_NO_RET, ++ alternative_input("", "DO_OVERWRITE_RSB xu=%=", X86_BUG_IBPB_NO_RET, + : "rax", "rcx"); + } + +@@ -172,7 +172,7 @@ static always_inline void spec_ctrl_enter_idle(struct cpu_info *info) + * + * (ab)use alternative_input() to specify clobbers. + */ +- alternative_input("", "DO_OVERWRITE_RSB", X86_FEATURE_SC_RSB_IDLE, ++ alternative_input("", "DO_OVERWRITE_RSB xu=%=", X86_FEATURE_SC_RSB_IDLE, + : "rax", "rcx"); + } + +diff --git a/xen/include/asm-x86/spec_ctrl_asm.h b/xen/include/asm-x86/spec_ctrl_asm.h +index 9eb4ad9ab7..b61a5571ae 100644 +--- a/xen/include/asm-x86/spec_ctrl_asm.h ++++ b/xen/include/asm-x86/spec_ctrl_asm.h +@@ -117,11 +117,16 @@ + .L\@_done: + .endm + +-.macro DO_OVERWRITE_RSB tmp=rax ++.macro DO_OVERWRITE_RSB tmp=rax xu + /* + * Requires nothing + * Clobbers \tmp (%rax by default), %rcx + * ++ * xu is an optional parameter to add eXtra Uniqueness. It is intended for ++ * passing %= in from an asm() block, in order to work around ++ * https://github.com/llvm/llvm-project/issues/60792 where Clang-IAS doesn't ++ * expand \@ uniquely. ++ * + * Requires 256 bytes of {,shadow}stack space, but %rsp/SSP has no net + * change. Based on Google's performance numbers, the loop is unrolled to 16 + * iterations and two calls per iteration. +@@ -137,31 +142,31 @@ + mov $16, %ecx /* 16 iterations, two calls per loop */ + mov %rsp, %\tmp /* Store the current %rsp */ + +-.L\@_fill_rsb_loop: ++.L\@_fill_rsb_loop\xu: + + .irp n, 1, 2 /* Unrolled twice. */ +- call .L\@_insert_rsb_entry_\n /* Create an RSB entry. */ ++ call .L\@_insert_rsb_entry\xu\n /* Create an RSB entry. */ + +-.L\@_capture_speculation_\n: ++.L\@_capture_speculation\xu\n: + pause + lfence +- jmp .L\@_capture_speculation_\n /* Capture rogue speculation. */ ++ jmp .L\@_capture_speculation\xu\n /* Capture rogue speculation. */ + +-.L\@_insert_rsb_entry_\n: ++.L\@_insert_rsb_entry\xu\n: + .endr + + sub $1, %ecx +- jnz .L\@_fill_rsb_loop ++ jnz .L\@_fill_rsb_loop\xu + mov %\tmp, %rsp /* Restore old %rsp */ + + #ifdef CONFIG_XEN_SHSTK + mov $1, %ecx + rdsspd %ecx + cmp $1, %ecx +- je .L\@_shstk_done ++ je .L\@_shstk_done\xu + mov $64, %ecx /* 64 * 4 bytes, given incsspd */ + incsspd %ecx /* Restore old SSP */ +-.L\@_shstk_done: ++.L\@_shstk_done\xu: + #endif + .endm + +-- +2.40.0 + |