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{sysutils,emulators}/xen-{tools,kernel}: update to latest stable hash
Update the kernel and tools packages and also include a fix for a clang code generation bug. Sponsored by: Cloud Software Group Approved by: bapt (implicit)
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Roger Pau Monné
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,3 +1,3 @@ | ||
| TIMESTAMP = 1702977481 | ||
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| SIZE (xen-project-xen-1792d1723b7fb45a20b145d2de4d233913b22c09_GL0.tar.gz) = 6825501 | ||
| TIMESTAMP = 1708622887 | ||
| SHA256 (xen-project-xen-b1fdd7d0e47e0831ac7a99d0417385fc10d3068c_GL0.tar.gz) = 4cb7ef37b51d9d1ff58272fafebfa91d48aadacdb5cc4ee6f046488234be8c1b | ||
| SIZE (xen-project-xen-b1fdd7d0e47e0831ac7a99d0417385fc10d3068c_GL0.tar.gz) = 6826601 |
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emulators/xen-kernel/files/v2-0001-x86-altcall-use-an-union-as-register-type-for-fun.patch
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,137 @@ | ||
| From e0d563ca60b16dfab45956f60a6c1b7b1e218ba4 Mon Sep 17 00:00:00 2001 | ||
| From: Roger Pau Monne <roger.pau@citrix.com> | ||
| To: xen-devel@lists.xenproject.org | ||
| Cc: Jan Beulich <jbeulich@suse.com> | ||
| Cc: Andrew Cooper <andrew.cooper3@citrix.com> | ||
| Cc: "Roger Pau Monné" <roger.pau@citrix.com> | ||
| Cc: Wei Liu <wl@xen.org> | ||
| Date: Wed, 21 Feb 2024 16:55:12 +0100 | ||
| Subject: [PATCH v2] x86/altcall: use an union as register type for function | ||
| parameters | ||
| MIME-Version: 1.0 | ||
| Content-Type: text/plain; charset=UTF-8 | ||
| Content-Transfer-Encoding: 8bit | ||
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| The current code for alternative calls uses the caller parameter types as the | ||
| types for the register variables that serve as function parameters: | ||
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| uint8_t foo; | ||
| [...] | ||
| alternative_call(myfunc, foo); | ||
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| Would expand roughly into: | ||
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| register unint8_t a1_ asm("rdi") = foo; | ||
| register unsigned long a2_ asm("rsi"); | ||
| [...] | ||
| asm volatile ("call *%c[addr](%%rip)"...); | ||
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| However under certain circumstances clang >= 16.0.0 with -O2 can generate | ||
| incorrect code, given the following example: | ||
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| unsigned int func(uint8_t t) | ||
| { | ||
| return t; | ||
| } | ||
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| static void bar(uint8_t b) | ||
| { | ||
| int ret_; | ||
| register uint8_t di asm("rdi") = b; | ||
| register unsigned long si asm("rsi"); | ||
| register unsigned long dx asm("rdx"); | ||
| register unsigned long cx asm("rcx"); | ||
| register unsigned long r8 asm("r8"); | ||
| register unsigned long r9 asm("r9"); | ||
| register unsigned long r10 asm("r10"); | ||
| register unsigned long r11 asm("r11"); | ||
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| asm volatile ( "call %c[addr]" | ||
| : "+r" (di), "=r" (si), "=r" (dx), | ||
| "=r" (cx), "=r" (r8), "=r" (r9), | ||
| "=r" (r10), "=r" (r11), "=a" (ret_) | ||
| : [addr] "i" (&(func)), "g" (func) | ||
| : "memory" ); | ||
| } | ||
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| void foo(unsigned int a) | ||
| { | ||
| bar(a); | ||
| } | ||
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| Clang generates the following code: | ||
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| func: # @func | ||
| movl %edi, %eax | ||
| retq | ||
| foo: # @foo | ||
| callq func | ||
| retq | ||
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| Note the truncation of the unsigned int parameter 'a' of foo() to uint8_t when | ||
| passed into bar() is lost. | ||
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| The above can be worked around by using an union when defining the register | ||
| variables, so that `di` becomes: | ||
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| register union { | ||
| uint8_t e; | ||
| unsigned long r; | ||
| } di asm("rdi") = { .e = b }; | ||
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| Which results in following code generated for `foo()`: | ||
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| foo: # @foo | ||
| movzbl %dil, %edi | ||
| callq func | ||
| retq | ||
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| So the truncation is not longer lost. Apply such workaround only when built | ||
| with clang. | ||
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| Reported-by: Matthew Grooms <mgrooms@shrew.net> | ||
| Link: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=277200 | ||
| Link: https://github.com/llvm/llvm-project/issues/82598 | ||
| Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> | ||
| --- | ||
| Changes since v1: | ||
| - Only apply the union workaround with clang. | ||
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| Seems like all gitlab build tests are OK with this approach. | ||
| --- | ||
| xen/arch/x86/include/asm/alternative.h | 16 ++++++++++++++++ | ||
| 1 file changed, 16 insertions(+) | ||
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| diff --git a/xen/arch/x86/include/asm/alternative.h b/xen/arch/x86/include/asm/alternative.h | ||
| index a1cd6a9fe5b8..3fe27ea791bf 100644 | ||
| --- a/xen/arch/x86/include/asm/alternative.h | ||
| +++ b/xen/arch/x86/include/asm/alternative.h | ||
| @@ -167,9 +167,25 @@ extern void alternative_branches(void); | ||
| #define ALT_CALL_arg5 "r8" | ||
| #define ALT_CALL_arg6 "r9" | ||
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| +#ifdef CONFIG_CC_IS_CLANG | ||
| +/* | ||
| + * Use an union with an unsigned long in order to prevent clang from skipping a | ||
| + * possible truncation of the value. By using the union any truncation is | ||
| + * carried before the call instruction. | ||
| + * https://github.com/llvm/llvm-project/issues/82598 | ||
| + */ | ||
| +#define ALT_CALL_ARG(arg, n) \ | ||
| + register union { \ | ||
| + typeof(arg) e; \ | ||
| + unsigned long r; \ | ||
| + } a ## n ## _ asm ( ALT_CALL_arg ## n ) = { \ | ||
| + .e = ({ BUILD_BUG_ON(sizeof(arg) > sizeof(void *)); (arg); }) \ | ||
| + } | ||
| +#else | ||
| #define ALT_CALL_ARG(arg, n) \ | ||
| register typeof(arg) a ## n ## _ asm ( ALT_CALL_arg ## n ) = \ | ||
| ({ BUILD_BUG_ON(sizeof(arg) > sizeof(void *)); (arg); }) | ||
| +#endif | ||
| #define ALT_CALL_NO_ARG(n) \ | ||
| register unsigned long a ## n ## _ asm ( ALT_CALL_arg ## n ) | ||
|
|
||
| -- | ||
| 2.43.0 | ||
|
|
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