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Hi,
✅ All tests passed successfully. No issues detected. No action required from the submitter.
The upstream commit SHA1 provided is correct: f4818881c47fd91fcb6d62373c57c7844e3de1c0
Status in newer kernel trees: 6.14.y | Present (different SHA1: 2530e9327957) 6.12.y | Present (different SHA1: 29a3e7d59cac) 6.6.y | Present (different SHA1: 527b6f385495) 6.1.y | Present (different SHA1: 39fdd17f075d)
Note: The patch differs from the upstream commit: --- 1: f4818881c47fd ! 1: e0aa87dadeb43 x86/its: Enable Indirect Target Selection mitigation @@ Metadata ## Commit message ## x86/its: Enable Indirect Target Selection mitigation
+ commit f4818881c47fd91fcb6d62373c57c7844e3de1c0 upstream. + Indirect Target Selection (ITS) is a bug in some pre-ADL Intel CPUs with eIBRS. It affects prediction of indirect branch and RETs in the lower half of cacheline. Due to ITS such branches may get wrongly predicted @@ Documentation/admin-guide/kernel-parameters.txt Format: <full_path> Run specified binary instead of /sbin/init as init @@ + improves system performance, but it may also expose users to several CPU vulnerabilities. - Equivalent to: if nokaslr then kpti=0 [ARM64] - gather_data_sampling=off [X86] + Equivalent to: gather_data_sampling=off [X86] + indirect_target_selection=off [X86] + kpti=0 [ARM64] kvm.nx_huge_pages=off [X86] l1tf=off [X86] - mds=off [X86]
## arch/x86/kernel/cpu/bugs.c ## @@ arch/x86/kernel/cpu/bugs.c: static void __init srbds_select_mitigation(void); static void __init l1d_flush_select_mitigation(void); - static void __init srso_select_mitigation(void); static void __init gds_select_mitigation(void); + static void __init srso_select_mitigation(void); +static void __init its_select_mitigation(void);
/* The base value of the SPEC_CTRL MSR without task-specific bits set */ u64 x86_spec_ctrl_base; @@ arch/x86/kernel/cpu/bugs.c: static DEFINE_MUTEX(spec_ctrl_mutex);
- void (*x86_return_thunk)(void) __ro_after_init = __x86_return_thunk; + void (*x86_return_thunk)(void) __ro_after_init = &__x86_return_thunk;
+static void __init set_return_thunk(void *thunk) +{ @@ arch/x86/kernel/cpu/bugs.c: void __init cpu_select_mitigations(void)
/* @@ arch/x86/kernel/cpu/bugs.c: static void __init retbleed_select_mitigation(void) - setup_force_cpu_cap(X86_FEATURE_RETHUNK); setup_force_cpu_cap(X86_FEATURE_UNRET);
-- x86_return_thunk = retbleed_return_thunk; -+ set_return_thunk(retbleed_return_thunk); + if (IS_ENABLED(CONFIG_RETHUNK)) +- x86_return_thunk = retbleed_return_thunk; ++ set_return_thunk(retbleed_return_thunk);
if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD && boot_cpu_data.x86_vendor != X86_VENDOR_HYGON) -@@ arch/x86/kernel/cpu/bugs.c: static void __init retbleed_select_mitigation(void) - setup_force_cpu_cap(X86_FEATURE_RETHUNK); - setup_force_cpu_cap(X86_FEATURE_CALL_DEPTH); - -- x86_return_thunk = call_depth_return_thunk; -+ set_return_thunk(call_depth_return_thunk); - break; - - default: @@ arch/x86/kernel/cpu/bugs.c: static void __init retbleed_select_mitigation(void) pr_info("%s\n", retbleed_strings[retbleed_mitigation]); } @@ arch/x86/kernel/cpu/bugs.c: static void __init retbleed_select_mitigation(void) +enum its_mitigation { + ITS_MITIGATION_OFF, + ITS_MITIGATION_ALIGNED_THUNKS, -+ ITS_MITIGATION_RETPOLINE_STUFF, +}; + +static const char * const its_strings[] = { + [ITS_MITIGATION_OFF] = "Vulnerable", + [ITS_MITIGATION_ALIGNED_THUNKS] = "Mitigation: Aligned branch/return thunks", -+ [ITS_MITIGATION_RETPOLINE_STUFF] = "Mitigation: Retpolines, Stuffing RSB", +}; + +static enum its_mitigation its_mitigation __ro_after_init = ITS_MITIGATION_ALIGNED_THUNKS; @@ arch/x86/kernel/cpu/bugs.c: static void __init retbleed_select_mitigation(void) + return; + } + -+ /* Retpoline+CDT mitigates ITS, bail out */ -+ if (boot_cpu_has(X86_FEATURE_RETPOLINE) && -+ boot_cpu_has(X86_FEATURE_CALL_DEPTH)) { -+ its_mitigation = ITS_MITIGATION_RETPOLINE_STUFF; -+ goto out; -+ } -+ + /* Exit early to avoid irrelevant warnings */ + if (cmd == ITS_CMD_OFF) { + its_mitigation = ITS_MITIGATION_OFF; @@ arch/x86/kernel/cpu/bugs.c: static void __init retbleed_select_mitigation(void) + its_mitigation = ITS_MITIGATION_OFF; + goto out; + } -+ if (!IS_ENABLED(CONFIG_MITIGATION_RETPOLINE) || -+ !IS_ENABLED(CONFIG_MITIGATION_RETHUNK)) { ++ if (!IS_ENABLED(CONFIG_RETPOLINE) || !IS_ENABLED(CONFIG_RETHUNK)) { + pr_err("WARNING: ITS mitigation depends on retpoline and rethunk support\n"); + its_mitigation = ITS_MITIGATION_OFF; + goto out; @@ arch/x86/kernel/cpu/bugs.c: static void __init srso_select_mitigation(void) - x86_return_thunk = srso_return_thunk; + set_return_thunk(srso_return_thunk); } - if (has_microcode) - srso_mitigation = SRSO_MITIGATION_SAFE_RET; + srso_mitigation = SRSO_MITIGATION_SAFE_RET; + } else { @@ arch/x86/kernel/cpu/bugs.c: static ssize_t rfds_show_state(char *buf) return sysfs_emit(buf, "%s\n", rfds_strings[rfds_mitigation]); } @@ arch/x86/kernel/cpu/bugs.c: ssize_t cpu_show_reg_file_data_sampling(struct devic + return cpu_show_common(dev, attr, buf, X86_BUG_ITS); +} #endif - - void __warn_thunk(void)
## drivers/base/cpu.c ## -@@ drivers/base/cpu.c: CPU_SHOW_VULN_FALLBACK(spec_rstack_overflow); - CPU_SHOW_VULN_FALLBACK(gds); - CPU_SHOW_VULN_FALLBACK(reg_file_data_sampling); - CPU_SHOW_VULN_FALLBACK(ghostwrite); -+CPU_SHOW_VULN_FALLBACK(indirect_target_selection); +@@ drivers/base/cpu.c: ssize_t __weak cpu_show_reg_file_data_sampling(struct device *dev, + return sysfs_emit(buf, "Not affected\n"); + }
++ssize_t __weak cpu_show_indirect_target_selection(struct device *dev, ++ struct device_attribute *attr, char *buf) ++{ ++ return sysfs_emit(buf, "Not affected\n"); ++} ++ static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL); static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL); -@@ drivers/base/cpu.c: static DEVICE_ATTR(spec_rstack_overflow, 0444, cpu_show_spec_rstack_overflow, NU + static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL); +@@ drivers/base/cpu.c: static DEVICE_ATTR(retbleed, 0444, cpu_show_retbleed, NULL); static DEVICE_ATTR(gather_data_sampling, 0444, cpu_show_gds, NULL); + static DEVICE_ATTR(spec_rstack_overflow, 0444, cpu_show_spec_rstack_overflow, NULL); static DEVICE_ATTR(reg_file_data_sampling, 0444, cpu_show_reg_file_data_sampling, NULL); - static DEVICE_ATTR(ghostwrite, 0444, cpu_show_ghostwrite, NULL); +static DEVICE_ATTR(indirect_target_selection, 0444, cpu_show_indirect_target_selection, NULL);
static struct attribute *cpu_root_vulnerabilities_attrs[] = { &dev_attr_meltdown.attr, @@ drivers/base/cpu.c: static struct attribute *cpu_root_vulnerabilities_attrs[] = { &dev_attr_gather_data_sampling.attr, + &dev_attr_spec_rstack_overflow.attr, &dev_attr_reg_file_data_sampling.attr, - &dev_attr_ghostwrite.attr, + &dev_attr_indirect_target_selection.attr, NULL }; @@ drivers/base/cpu.c: static struct attribute *cpu_root_vulnerabilities_attrs[] =
## include/linux/cpu.h ## @@ include/linux/cpu.h: extern ssize_t cpu_show_gds(struct device *dev, + struct device_attribute *attr, char *buf); extern ssize_t cpu_show_reg_file_data_sampling(struct device *dev, struct device_attribute *attr, char *buf); - extern ssize_t cpu_show_ghostwrite(struct device *dev, struct device_attribute *attr, char *buf); +extern ssize_t cpu_show_indirect_target_selection(struct device *dev, + struct device_attribute *attr, char *buf);
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Results of testing on various branches:
| Branch | Patch Apply | Build Test | |---------------------------|-------------|------------| | stable/linux-6.1.y | Success | Success |